A handful of politicians seek to extend Daylight Saving Time (DST) to the full year. Biannual clock-switching is harmful, but year-round DST is worse, even deadly.
Year-round Standard Time instead would save lives, improve physical and mental health, reduce pollution, slow global warming, and save money. It’s for good reason that year-round DST has long been discouraged by law. Legislate by data, not anecdote.
Assemblymember Kansen Chu authored Prop 7 to end clock switches. Following its approval, he authored Assembly Bill 7 (AB 7) to enact year-round DST. Prop 7 was presented in endorsement guides as an end to DST, not an extension. Ballots never mentioned year-round DST. Chu has no personal preference, but heard more constituent leaning to DST. AB 7 awaits a Senate Energy Committee hearing.
Global experts and local residents, please contact Mr Chu by webform (a25.asmdc.org), email (firstname.lastname@example.org), and phone (+1-916-319-2025) to urge he amend AB 7 to year-round Standard Time.
Email position letters to Committee Assistant Melanie Cain (email@example.com). Letters must clearly state opposition. Letterhead with signature is preferable. Letters from organizations are public, from individuals are anonymous. The Senate “Portal” has lost uploaded documents—better to email.
Testify at a Committee hearing. No registration needed, simply appear on time and express intention to speak.
Contact state representatives to urge they oppose AB 7 and introduce new legislation to restore year-round Standard Time.
Both the change of clocks to DST and the continual observation of DST are lethal to human health.
The abrupt move forward in springtime by one hour is well-known for its shock to body and mind—causing traffic deaths, workplace accidents, lost productivity, and hospitalizations. Incidence of stroke increases 9% upon switching to DST in spring. Incidence of heart attack increases 24 to 50% after switching to DST, and it decreases 21% after returning to Standard Time in autumn. These acute effects persist for four days after switching clocks forward.
Circadian biologists have also found that remaining on DST causes continual harm—that we never fully adjust to DST, we merely sleep less long and less well than we need.
Healthful sleep is necessary for prosperity and longevity, and it’s biologically regulated by melatonin and cortisol. The body’s natural release of these sleeping and waking hormones is tuned to the setting and rising of the sun. DST postpones both sunset and sunrise on our social clock, which disrupts the body’s hormone balance, and leads people both to stay awake late and to feel a need to sleep late. However, social schedules demand we wake on time regardless of how we feel, and year-round DST would demand we wake before sunrise for roughly half of the year.
DST’s combination of late daylight and pre-sunrise waking robs us of 19 minutes of sleep every night on average. Cortisol rhythms advance only two minutes despite clocks being advanced 60 minutes under DST. This creates a “social jet lag”, which is far worse for health than ordinary jet lag, and which never is relieved under year-round DST. The body attempts to compensate by sleeping late on non–work days, but the benefits of sleep can’t be stored.
DST’s chronic lack of sleep increases risks of heart disease, stroke, diabetes, cancer, epileptic seizures, high blood pressure, obesity, metabolic disorders, personality disorders, unintentional midday sleep, caffeine abuse, alcohol abuse, depression, and suicidality. It harms cognition, productivity, reaction time, stress management, and life expectancy, in both children and adults. Delaying sunset and sunrise by one hour increases breast and prostate cancer rates by up to 12%, lung and colorectal cancer 14%, liver cancer 21%, stomach cancer 27%, uterine cancer 30%, leukemia 36%, and esophageal cancer 48%. Seasonal depression is more prevalent at northerly latitudes (10% of Seattle, 25% of Alaska), where winter days are unavoidably shorter. This suffering is most effectively relieved by adding light to mornings—not evenings.
Some claim DST may increase exercise. However, the study to back this claim only considered regions that observe summer DST (ignoring those on year-round Standard Time), its gains averaged just two minutes per day (not the full hour the clock gets advanced), and these small gains were seen only in Europe and Australia (with no gains in America). Another study that did compare close regions with different time observations found no increase or decrease in exercise. Furthermore, evening exercise can disrupt sleep, and lack of sleep can increase sports injuries by 70%.
The Center for Circadian Biology, the Society for Research on Biological Rhythms, the European Biological Rhythms Society, and the European Sleep Research Society have all opposed year-round DST, citing its continual disruption to sleep cycles.
DST kills commuting children and adults, whether we observe it seasonally or year-round.
The springtime switch to DST shocks the human circadian system with a sudden loss of 40 minutes of sleep on average. This disruption negatively affects reaction times, which causes traffic deaths in the US to spike 17% the Monday after switching to DST. The increase in road deaths persists at 5.6% the remaining week after switching. The lives of up to 195 motorists and 171 pedestrians are lost due to ”springing forward” each year.
Furthermore, year-round DST would force us to begin work or school before sunrise for roughly half of the year. Mornings are the worst time for dark commutes, when grogginess from lack of sleep (19 minutes lost every night under DST) is strongest for walking or busing children, inexperienced teen drivers, and driving adults alike. Motor vehicle accidents are the primary cause of accidental death in the US. 70% of all US pedestrian deaths occur under darkness, and 20% of all US pedestrians killed are children. In 1974, eight kids died on dark winter mornings in just one month of year-round DST in Florida.
The National Education Association, the American Federation of Teachers, the National School Boards Association, and the National PTA have all opposed year-round DST, citing children’s safety.
Energy & Environment
DST wastes energy and increases pollution. Stealing an hour of daylight from mornings to add to evenings might reduce evening lighting costs as originally promised, but it’s offset by increased morning lighting, and lighting is no longer a considerable energy expense. Instead, DST increases demand both for morning heat (since it wakes us before sunrise) and evening air conditioning (since it keeps us awake when solar build-up is strongest). DST also encourages more evening driving, leading the petroleum and retail industries to become major lobbies for extensions of DST. These increases to heating, air conditioning, and driving all increase energy costs, pollution, and global warming. It’s a chief reason why Arizona observes year-round Standard Time.
When Indiana switched from year-round Standard Time to summertime DST in 2007, annual consumer electricity demand rose 1 to 4%. This jump cost residents an extra $9M per year in utilities, and up to $5.5M annually in added pollution expenses. The same effect was seen in Sydney, Australia, when DST was extended for the 2000 Summer Olympics. Energy waste could be even worse in regions with greater populations or more extreme weather.
Both switching to DST and remaining on DST have high economic costs, which manifest as stock-market disruption, lost productivity, workplace injuries, healthcare expenses, and overall lower earnings.
Workplace injuries in US laborers increase 5.7% in the days after moving clocks forward in spring, due to the sudden loss of an average of 40 minutes of sleep. Injuries increase in severity too, resulting in 67% more days lost after switching clocks forward. US office productivity drops 20% after springtime switching, for a loss of $434M annually nationwide. Stocks drop 200 to 500% more than usual the Monday after moving clocks forward to DST, at a cost of $31B in the US. These injuries, missed days, lost productivity, and stock losses don’t reoccur in the autumn return to Standard Time, nor are they ever recouped.
Economic losses continue under DST beyond the springtime clock switch, as seen in data from western and eastern edges of time zones, where sunsets and sunrises naturally differ by an hour. One added hour of sunlight in evenings and its corresponding lost hour in mornings reduce sleep duration by an average of 19 minutes nightly. This continual loss of sleep every night manifests as health problems (at a cost of $2.35B annually in the US), as lost productivity (totaling 4.4M lost work days, at a cost of $613M annually nationwide), and even as lower earnings (3.0 to 4.9% less than in neighboring counties with a one-hour earlier sunset and sunrise). An increase in average nightly sleep by a full hour can increase earnings by the same amount as half a year of added education would, and it can increase productivity more than an entire year of added education.
DST disrupts religious communities. Judaism, for example, calls for morning prayers at sunrise, which would unfairly overlap with work hours under year-round DST. Agudath Israel of America, Agudath Israel of California, Agudath Israel of Florida, the Rabbinical Council of America, the Rabbinical Council of California, and Adath Israel of San Francisco have all opposed year-round DST.
Year-round DST makes sunrises too late. Under year-round DST, sunrise would be as late as 8:44am in California, 8:56am in Texas, 8:46am in New York, 9:01am in Ohio, 8:40am in North Carolina, 9:33am in Michigan, 9:44am in the contiguous US, and 10:04am in British Columbia.
Sunrises after 8am DST would last as many as 15 weeks (3.5 months) in California, 20 weeks (4.7 months) in Texas, 15 weeks (3.5 months) in New York, 19 weeks (4.3 months) in Ohio, 16 weeks (3.7 months) in North Carolina, 22 weeks (5.2 months) in Michigan, 24 weeks (5.4 months) in the contiguous US, and 20 weeks (4.7 months) in British Columbia.
No survey has shown definitively which time the populace prefers. Most people don’t know which time is which (granted, it can be confusing). Preference between the two times is rarely asked, and polls depend heavily on how and when they’re conducted. Many people think they prefer DST, but they usually just prefer summer’s naturally longer days, without realizing how dark winter mornings would be under year-round DST.
Those who favor one time or the other are generally split (35% DST vs 28% Standard in a 2019 March poll of 1,288 Americans; 47% Standard vs 41% DST in a 2019 February poll of 1,030 Seattleites).
The majority clearly wish to stop switching clocks as soon as possible (84% in a 2018 poll of 4.6M Europeans; 67% in a 2018 poll of 600 Pacific Northwesterners; 60% in California’s 2018 Prop 7 ballot measure; 54% in a 2019 poll of 1,288 Americans).
History has shown when public opinion favors year-round DST before enactment, support quickly reverses to opposition after DST’s long, dark winter mornings are experienced (as happened in the UK in 1971, the US in 1974, and Russia in 2014).
Public opinion demands we stop switching clocks now. The quickest, easiest, safest way is to restore year-round Standard Time. Moreover, public health demands we both stop switching clocks now and choose year-round Standard Time. Public health must take precedence over shifting public opinion of the two times.
Learn from History
The US tried year-round DST in 1974. While initially supported by an estimated 79% of the population, its popularity quickly plummeted to 42% after its first winter. Several children died on their way to school, the public bemoaned the unnaturally late, dark mornings, and the two-year experiment was ended a year and a half early.
Year-round DST was similarly tried in the UK from 1968 to 1971, and in Russia from 2011 to 2014. Each time, the program was greeted with initial optimism, followed by public outcry and reversal.
No bill can make winter’s daylight as long as summer’s daylight. DST is mistakenly associated with summer’s naturally longer days, but summer days will still be just as long under year-round Standard Time as they were under DST.
DST is akin to “vanity sizing”, wherein clothiers arbitrarily assign different numbers to the same sizes to make consumers feel thinner. DST’s arbitrarily added hour falsely makes some people feel they have more daylight. We could add six hours to the clock to keep sun up until a false midnight, but it would then be dark until the false noon.
DST also leads to an unsustainable “arms race”. We push the clock forward for more after-work daylight, then we push start times forward for more pre-work rest, which cancels the after-work daylight. Calls have already begun to delay work hours until 10am DST (which is only 9am Standard). The benefits of starting school later would also be canceled by year-round DST (and helped by year-round Standard Time).
Standard Time is the most practical model for timekeeping that is based in objective reality. It’s an approximation of solar time, which is itself a geometric measurement of nature. Twelve noon corresponds to the sun’s highest point in the sky; twelve midnight corresponds to the darkest point of night. Twelve was chosen for its even fractions (half, third, quarter).
Standard Time facilitates many simple estimations: time of day from the sun’s position, time of night from the moon or stars, time of sunrise or sunset, time zone differences, latitude on earth, sunburn hours… This knowledge—this connection to nature—is needlessly obscured under Daylight Saving.
The simplest way to end clock changes is to restore year-round Standard Time. In both the US and Canada, year-round Standard Time could end clock switches in mere months, with no need for Federal action. Arizona, Hawaii, all US territories, and Northeastern British Columbia did this long ago, and no complaints have been heard since.
The pursuit instead for year-round DST would require sweeping change to Federal law by Congress—which would take several years, which might never occur, or which might be changed then reverted (as happened in 1974). Year-round DST defies the people’s will for an immediate end to clock switches; it’s a waste of legislative time and taxpayer money.
A return instead to year-round Standard Time would cost nothing and could be enacted this year. It would benefit public health, public safety, the environment, the economy—and it would be an easy win for lawmakers.
Save Standard Time is wholly a grassroots, volunteer effort, founded by a software engineer, amateur astronomer, and conservationist, in San Francisco.
- Ackerman, Ximei; Phan, Tiffany; Landaverde, Maryanna Sophia; Lee, Stuart; Seluzicki, Adam; Golden, Susan S (2019). “Daylight Saving Time Effects”. Center for Circadian Biology. “Our internal clocks are set by the sun, but our social clocks are dictated by time zones. Sun Time differs between eastern and western edges of each time zone. On the western edge, Sun and Social Times are out of sync, causing health and social problems. Daylight Saving Time, a one-hour ‘spring forward,’ causes even more misalignment between Sun and Social Times.”
- Berk, Michael; Dodd, Seetal; Hallam, Karen; Berk, Lesley; Gleeson, John; Henry, Margaret (2008). “Small Shifts in Diurnal Rhythms Are Associated with an Increase in Suicide: The Effect of Daylight Saving”. Sleep and Biological Rhythms. “Male suicide rates rise in the weeks following the commencement of daylight saving, compared to the weeks following the return to eastern standard time and for the rest of the year… Small changes in chronobiological rhythms are potentially destabilizing in vulnerable individuals.”
- Block, Gene; Meijer, Johanna (2019). “Who Wants to Go to Work in the Dark? Californians Need Permanent Standard Time”. UCLA Newsroom. “[C]hoosing permanent daylight saving time could create real health and safety issues… [L]ack of morning light can have serious impact on our biological clocks, which control the body’s many daily rhythms including our sleep and wakefulness cycle. Humans require adequate morning light so that our internal biological rhythms synchronize properly to the local time. There’s a wealth of data demonstrating that a lack of exposure to light leads to sleep and metabolic disorders, depression and cardiovascular disease, among other ailments… Permanent standard time is the only fair and viable option, not only for California, but the entire nation. California lawmakers, regardless of district, have a responsibility to residents in the northern part of the state. They also have an opportunity to make this important point to Congress, which might someday impose a permanent time change for the nation.”
- Brueck, Hilary (2019). “Daylight-Saving Time Is Literally Killing Us”. Business Insider. “Just a coincidence? Probably not. Doctors see the opposite trend in the fall: The day after we turn back the clocks, heart attack visits drop 21%.”
- Clay, Joanna (2019). “Is Year-Round Daylight Saving Time a Good Idea? Maybe Not”. USC News. “USC experts confirm biological challenges of the time change; if anything, they say we should be on standard time all year… Much like the jet lag we experience after flying across time zones, losing an hour upsets our circadian rhythm. That not only throws off our sleep schedule but actually has impacts on the cellular level, since many biological functions are timed to that clock… It affects human performance. The data has been clear in terms of traffic accidents and there’s also data that it’s not great in terms of cardiovascular health: Heart attacks go up… Research shows there are all kinds of health concerns when it comes to circadian disruption. When experienced long term, as is the case with night shift workers, an individual’s likelihood to develop obesity, Type 2 diabetes or cancer increases, according to USC experts… USC experts say [politicians are] missing the mark. Permanent daylight saving time wouldn’t solve this issue; instead, it would prolong it—adding more days of social jet lag to the year… [E]xperiencing light when you first get up is good for you… Longcore noted a study on four million Americans, comparing how far east they lived in their time zone with cancer rates. People who lived west within their time zones saw impacts: each 20 minutes of later sunrise increased certain cancers by 4 to 12 percent.”
- Herf, Michael (2019). “Why Standard Time Is Better”. Medium.com. “Thousands of scientists say that Standard Time is better, yet legislators are pushing for permanent DST, anyway. The scientists have shown that seeing light in the morning is essential to health, and without it we get more cancer, diabetes, and obesity… [W]aking up in the dark is tough on our internal clocks and our sleep… [T]he best numbers say that making people wake up an hour earlier could give us 10–20% more cancer… The two largest groups of scientists researching circadian rhythms have issued statements with a strong preference for standard time… [T]he advantages of permanent ST outweigh switching to DST annually or permanently… [I]nstalling perennial Standard Time (ST, or ‘wintertime’) is the best and safest option for public health...ST will be healthier than DST in terms of sleep, cardiac function, weight, cancer risk, and alcohol and tobacco consumption… Standard Time improves our sleep and will be healthier for our heart and our weight. The incidence of cancer will decrease in addition to alcohol and tobacco consumption. People will be psychologically healthier and performance at school and work will improve… Without this ‘light-kick’ in the morning, our biological clock drifts and our bodies are no longer able to perform according to the demands of the time of day… Humans require adequate morning light so that our internal biological rhythms synchronize properly to the local time. There’s a wealth of data demonstrating that a lack of exposure to light leads to sleep and metabolic disorders, depression and cardiovascular disease, among other ailments… Permanent daylight saving time wouldn’t solve this issue; instead, it would prolong it—adding more days of social jet lag to the year… Let’s imagine we took this too far and asked everyone to wake up super-early, at 3AM… [Y]our internal clock sets itself based on when you see bright light… [E]ven if we kept this up for years, most people wouldn’t get used to this schedule… We have to align our sleep with the light we see. And of course it doesn’t make any difference if we move the clocks so that 3AM is called 7AM—you can’t fool the body’s clock… Sleeping a half hour less actually does make a big difference for your health over time, but it’s hard to tell when you’re just a little off from your best schedule—you might start to feel burned out, hungry, or irritable. Over time, these small bits of sleep loss add up into large effects on our health. When scientists study sleep in larger populations, they can see these effects fast… When your clock is set much later than the alarm clock, you have trouble falling asleep at night and trouble waking up in the morning… In 1974, the United States decided to try permanent DST for two years, in order to save energy. At first, people were optimistic (79% were in favor of the move), but by February, after the first winter, support had dropped to 42%. Remember, the winters are tough. The US in 1974 didn’t make it the full two years: Congress rolled back the measure in a 383-to-16 vote. In 2011, Russia tried changing to DST all over the country. Again, the measure was initially very popular, but within a year, traffic accidents had gone up and the measure was unpopular. They reversed the decision in 2014, and they now use standard time… In men, twenty minutes of later sunrise gives 9% more stomach cancer, 11% more liver cancer, 4% more prostate cancer, and 13% more leukemia. In women, the same twenty minutes gives 3.7% more breast cancer, 16% more esophageal cancer, 4.5% more colorectal cancer, 4.6% more lung cancer, and 10% more uterine cancer… [P]eople do not get ‘used to’ the sleep restriction they experience when clocks are set earlier. They sleep less. According to their data, Standard Time lets people sleep more and reduces social jetlag. In 2012, Roenneberg’s team also showed that those with more social jetlag from sleeping at the wrong time tend to be more obese, even when they sleep the same number of hours. ‘Overall, our results indicate that sleep timing is an equally important predictor for BMI as is sleep duration.’ This means that a person who sleeps 8 hours a night, but at the wrong time, can still have poor sleep… Eve van Cauter’s group at University of Chicago demonstrated some of the important ways that sleep debt affects our waistlines. They asked people to sleep less, and then showed that they had decreased glucose tolerance and insulin sensitivity. These healthy people were responding as if they were pre-diabetic. When their sleep was restricted, people would also eat more the next day. From Jacqueline Lane and colleagues at Mass General Hospital, we learned that about a quarter of the population has a gene that predisposes them to Type 2 Diabetes, but only when they wake up early. When allowed to sleep past 7 AM, these people have a normal risk, and when woken up early, they have an 80% higher rate of diabetes… In places where the sun rises late in the winter (including northern California), rates of SAD, or seasonal depression, go up. Around 10% of people have winter depression in places like Seattle, and nearly 25% in Alaska. A majority of this group can feel better using bright light therapy (light boxes), a treatment which works best in the morning… For hundreds of years, noon was the time when the sun was directly overhead… [S]leeping well (and a lot) is the key to performance and recovery. We also know that sleep and exercise are closely related. First, tired people don’t exercise nearly as much, so anything that restricts sleep will make you do less activity. Next, exercising right before bed can disrupt your sleep, so you should do it a little earlier in the day. And finally, sports injuries go up considerably when sleep is restricted. A study of 112 adolescents shows that sleeping less than eight hours per night increases the risk of injury by 70%. Since sleeping 8 hours or more is protective of these kids, and because it makes people exercise more on their own, we should not encourage sports to the exclusion of sleep… [T]he text on the ballot and the voter guide almost avoided mentioning permanent DST… [N]obody has asked the question about which schedule voters prefer… Even if permanent ‘daylight time’ were the more popular vote (and it is favored by a lot of people), we think the public health evidence shows that higher obesity rates, higher cancer rates, higher accident rates, and more depression should sway the debate in the direction we have outlined here, to permanent standard time… Setting our clocks to Standard Time, so that noon is when the sun is directly overhead, is the sensible and better choice.”
- Herf, Michael; Longcore, Travis (2018). “Why Proposition 7 Is Bad for Public Health”. Medium.com. “[P]ermanent daylight saving time, is a cure that is worse than the disease… Getting up too early in the wintertime increases depression, cancer, and obesity. Year-round daylight saving time would make people wake up earlier than sunrise through the entire winter, with most people driving to work before sunrise. An inflexible daily work and school schedule forces people to get up before the sun, which disrupts the body’s daily cycle, known as a circadian rhythm… [W]e need light in the morning… [F]or each 20 minutes of later sunrise, breast and prostate cancer increase by 4%, leukemia around 12%, and uterine cancer by 10%. A second study reviewing nearly 60,000 cases found a 7% increase in liver cancer for every 20 minutes later sunrise… In 2011, Russia switched clocks to year-round ‘summer time.’ It was initially popular, but three years later only a third of Russians wanted to keep the system and it was abolished… Evidence is strong that standard time year-round is better for sleep, heart health, and healthy weight. It would reduce cancer incidence and improve psychological well-being of the population as a whole. Rather than chasing an illusion of permanent summer, voters should insist on a scientifically supported solution that benefits public health.”
- Ingraham, Christopher (2019). “How Living on the Wrong Side of a Time Zone Can Be Hazardous to Your Health”. The Washington Post. “[L]iving on the wrong side of a time zone’s boundary can have negative consequences on a person’s health and wallet. The culprit? More natural light in the evening hours… Sunset is a powerful biological trigger: The fading of natural light causes the body to release melatonin, a hormone that induces drowsiness. As a result, people on the eastern side of a time zone, where the sun sets earlier, tend to go to bed earlier than those on the western side… The problem for folks who go to bed later is that they generally cannot make up lost sleep on the back end: Work and school have set start times, whether you live in Pecos or Panama City. Individuals on the late sunset side of a time zone boundary are more likely to be sleep deprived, more likely to sleep less than 6 hours, and less likely to sleep at least 8 hours… Given what’s known about the importance of sleep for good physical and mental health, it’s no surprise that Giuntella and Mazzonna found a greater incidence of health problems in areas where the sun sets later. People on the late side of sunset across U.S. time zones were 11 percent more likely, on average, to be overweight and 21 percent more likely to be obese. Diabetes was more prevalent, and the risk of heart attack increased by 19 percent. Breast cancer rates were slightly elevated, too—about 5 percent higher than average. The authors also found economic differences. Sleeping less is known to adversely affect productivity. As a result, the researchers found, wages tend to be 3 percent lower on the late sunset side of the time zone border, suggesting negative effects on economic productivity.”
- Jin, Lawrence; Ziebarth, Nicolas R (2019). “Sleep, Health, and Human Capital: Evidence from Daylight Saving Time”. The National Bureau of Economic Research. “[I]nsufficient sleep leads to greater risk of car accidents and work injuries, as well as many chronic diseases and conditions such as high blood pressure, coronary heart disease, stroke, mental distress, and all-cause mortality… [R]ecent studies have identified causal relationships between inadequate sleep and reduced cognitive performance, reduced wage returns, higher car accidents, and higher incidences of obesity and diabetes. Hillman et al. (2006) estimate the economic costs of sleeplessness at almost one percent of GDP… [P]eople sleep significantly more in the short-run when they gain an additional hour at night following the DST ‘fall back.’ Moreover, the share of people who unintentionally fall asleep during the day drops significantly for four days. In addition, we find that hospital admissions drop sharply for four days as well. For example, cardiovascular admissions decrease by ten per one million population… Sleep deprivation is becoming a widespread problem in many developed countries—the CDC has recently declared it a ‘public health epidemic’. Almost a third of Americans report sleeping six or fewer hours, significantly less than the CDC-recommended minimum of 7 hours… [W]e assess the total societal benefits of gaining one hour of sleep with about $1.3 million per 1 million population. The benefits can be decomposed into work productivity, hospitalization, and mortality effects.”
- Livingston, Amy (2016). “Is Daylight Savings Time Helpful or Harmful? – History & Effects”. Money Crashers. “[M]ost Americans admit they don’t see the point of it—nearly half say it isn’t worthwhile, while only 33% think it is. In fact, some people argue that changing our clocks twice a year is actually harmful. They say tampering with our sleep schedules is bad for our health and makes us less productive at work, harming the economy… [T]he benefits of using DST to save energy are no longer as clear-cut… Indiana had actually increased its use of electricity by around 1% following the adoption of DST. The authors concluded that DST had reduced the need for lighting—but this change was offset by increased use of heating and air conditioning. Overall, they found that the change had cost the state $9 million in energy costs. Furthermore, they estimated there was an extra $1.7 to $5.5 million in ‘social costs’ from increased air pollution… [S]tudies suggest that people do drive more during DST. For example, a 1993 study in Science of the Total Environment found that DST leads to more traffic in the evenings, more fuel use, and more pollution. A 2008 analysis in Energy Policy points to several studies showing that increased gas consumption during DST more than offsets any energy savings from lower electricity use… [S]tudies show this isn’t just an annoyance—it’s actually a threat to our health. Changing the clocks disrupts our normal sleep patterns… [A] 2007 study in Current Biology suggests that we never adjust completely… [T]he switch to DST can make people depressed. A German study, published in Economics Letters, found that people’s mood and life satisfaction drop for about a week after the switch. An 2008 study in Sleep and Biological Rhythms found that in Australia, suicide rates rise in the weeks following the switch to DST… Several studies show that the number of heart attacks rises when DST starts. For example, a 2008 study in the New England Journal of Medicine looked at heart attack rates in Sweden dating back to 1987. It found that during the first week of DST, the rate was about 5% higher than normal. A 2010 study at the University of Alabama at Birmingham found an even bigger effect: Heart attack risk increases by 10% in the first two days after the switch to DST—and then drops by 10% after the switch back in the fall. Some people argue that extra daylight in the afternoon is good for our health because it encourages us to be more active. However, studies suggest this doesn’t really work. A 2014 study in the International Journal of Behavioral Nutrition and Physical Activity measured the activity level of children in nine countries before and after the time change. It found that European and Australian children only increased their outdoor play time by about two minutes for each extra hour of daylight—and American children didn’t increase it at all. A 2014 study of American adults in the Journal of Physical Activity and Health also found no increase in physical activity during DST… [M]ost farmers oppose DST because it messes with their schedules. Having less light in the morning gives them less time to get their crops ready to go to the market. And for dairy farmers, it’s difficult to deliver the milk an hour early, because cows prefer to be milked at the same time each day… Several scientists have also come to oppose DST after studying its health effects. David Wagner and Christopher Barnes, the authors of the two studies on DST in the Journal of Applied Psychology, argue that DST has ‘substantial costs, without any benefit.’”
- Medina, Diana; Ebben, Matthew; Milrad, Sara; Atkinson, Brianna; Krieger, Ana C (2015). “Adverse Effects of Daylight Saving Time on Adolescents’ Sleep and Vigilance”. Journal of Clinical Sleep Medicine. “Sleep duration declined by an average of 32 minutes on the weeknights post-DST… Vigilance significantly deteriorated…resulting in longer reaction times and increased lapses. Increased daytime sleepiness was also demonstrated.”
- Meijer, Johanna; Foster, Russell (2018). “Time to Change—But Only to ‘Wintertime’”. Daylight Academy. “[C]onstant ‘summertime’ is not the sensible option. Wintertime is a confusing term. Wintertime or geographical time is based on the actual time of sunrise and sunset. When our alarm clocks are set to the geographical time, the sun is at its highest point at noon and lowest at 24h midnight… A longer and brighter evening is inevitably at the expense of a later rise of the sun in the morning… [W]hen children travel to school and when the rush hour is at its height, we will be plunged into darkness or at best semi-darkness… [P]eople working in outdoor settings, such as construction workers, will suffer from ongoing darkness… [L]ack of morning light has a major impact upon the adjustment of our internal biological clock. This clock is present in the entire plant and animal kingdom, to fine-tune physiology and behavior to the daily light/dark cycle. In humans, even before we wake, this internal clock acts to increase blood pressure, metabolism, appetite and our cognitive abilities in anticipation of increased levels of activity… [I]ntroducing constant summertime is not as positive as one may think at a first sight. For at least 4 months in winter we will lack the correcting input of morning light resulting in a continuous jetlag…which promotes fatigue and lowers performance. No doubt, this will increase the incidence of traffic accidents in the morning… Apart from these immediate consequences, scientific research has revealed that ongoing distortion of our biological clocks leads to a wide variety of diseases, including metabolic abnormalities, cardiovascular disease and, most of all, an increased vulnerability to depression… [A] properly timed biological clock is essential for good overall mental and physical health.”
- O’Callaghan, Lauren (2016). “Early Riser? Waking Up Before Sunrise Increases Risk of a Stroke”. Express. “When the sun rises, the body’s melatonin—the hormone which helps people sleep naturally—is naturally suppressed. At the same time, the body’s internal cortisol levels, which gives people energy, rise. These hormones are disrupted when a person is forced to wake up instead of waking up naturally. An imbalance of these hormones is linked to an increased risk of strokes, heart disease, diabetes and depression.”
- Peralta, Jessica (2019). “Why Daylight Saving Time Makes You Feel Terrible”. Healthline. “‘Hoag completed a two-year-long study on this same topic, and found an increase of 50 percent in heart attack…we took into account all heart attack treatment, from medical management to angioplasty, stent, and bypass.’”
- Roenneberg, Till; Winnebeck, Eva C; Klerman, Elizabeth B (2019). “Daylight Saving Time and Artificial Time Zones – A Battle Between Biological and Social Times”. Frontiers in Physiology. “[T]he circadian clock plays a crucial role in how the outcome of these discussions potentially impacts our health and performance… The ‘master’ body clock in the nucleus suprachiasmaticus of the hypothalamus receives light via the retina and the optic nerves. The neurons of this master clock actively synchronize (or entrain) to the environment’s light–dark signals (zeitgeber) and in turn provide entraining signals for the circadian clocks in the rest of the body, i.e., the rest of the nervous system as well as peripheral organs and tissues. This process involves many components, most of which are proteins controlled by genes. The entraining process shows individual variations in the relationship between the body clock and the light–dark cycle (e.g., earlier or later)—the colloquial ‘larks’ and ‘owls,’ or chronotypes in general… When the social clock does not follow the large delays of the body clock, significant discrepancies between these two clocks arise; this so-called circadian misalignment can be assessed for some situations by calculating social jetlag (SJL), which is the difference between sleep-timing on work and work-free days… Although DST is mostly during summer months, DST is simply an advance of the social clock (we agree to do everything 1 h earlier) and does not ‘make it summer’… Standard Time refers to the social time defined by the time zone and has nothing to do with winter: it does not ‘make it winter’ nor cause short days, cold temperatures or snow… DST does not change day length or the time of sunset; day length changes with season in most parts of the world. During DST, people go to work an hour earlier (relative to sunrise) and come home an hour earlier (relative to sunset). It is correct that people can readily adapt to traveling one time zone west or east, but they adapt because their circadian clocks are exposed to the new natural light–dark cycle. DST, however, does NOT change the natural light–dark cycle. DST changes are therefore NOT comparable to traveling to different time zones. It is true that DST clock-changes are usually 1 h, but the relationship between sunrise and when we start work can change by many weeks. Also, a mismatch of 1 h/day is enough for adverse effects, especially if it lasts chronically for 7 months. Although the two opposite effects are true epidemiologically, the autumn ‘relief‘ cannot rescue the spring victim on an individual level. The spring victims can be only rescued by abolishing the clock advance (DST)… The human circadian clock can be set by both sunlight and artificial light, but sunlight is usually up to 1,000-fold more intense and has been shown to affect the clock’s synchronization even in mostly indoor-living people… Use of smart phones in the evening can delay the body clock. However, this effect does not compete with the light effects of DST, on the contrary, the two act additively in the same direction, thereby worsening social jetlag (SJL)… [T]he number of people NOT suffering from SJL doubles when switching away from perennial DST to Standard Time (e.g., time zone time) and the number of people suffering from higher levels of SJL are significantly and greatly reduced. There have been multiple attempts to implement perennial DST over the past 100 years (e.g., in Russia, the United Kingdom and the United States). In each of these cases, the ‘experiment’ was abandoned after few years… However, with DST, we do not change time, we only change social clocks; the sun clock with its midday and midnight remains the same and dawn and dusk continue their gradual seasonal photoperiodical/day-length changes. Importantly, days are not becoming additionally longer and the sun does not set additionally later because of DST, we simply come home earlier (in reference to the sun clock) because we start work or school earlier (in reference to the sun clock). DST changes are not comparable with time changes after transmeridian flight (known as jet lag) because we stay where we are instead of exposing our body clocks to the new light–dark cycles of our travel destination. People often belittle the effects of DST by stressing that ‘it’s only one hour.’ Note that this 1 h can actually translate into throwing our body clock’s relationship to social clock back weeks in the seasonal changes between sunrise and work start time… [T]he spring and the autumn effect do not balance each other out on the individual level and the higher risk in spring is avoidable by abolishing DST… [T]he risk for myocardial infarction was elevated throughout DST… [T]he combination of nighttime light exposure and DST is far worse than nighttime night exposure alone… [P]ermanent DST would increase the average SJL by more than half an hour which may be statistically small but is biologically large. The distributions published by Borisenkov and colleagues show that the transition from perennial DST to perennial Standard Time led to doubling of people who do not suffer from SJL, those who suffer from only 1 h SJL increased by about 30% and those who suffer from higher SJL are reduced by 25%. Therefore, Standard Time reduced SJL… The first days after the DST change in spring show acute effects: sleep is shortened, adolescents are sleepier during the day, general accidents and visits to the emergency room increase, so do myocardial infarctions, ischemic stroke, the risk of in vitro fertilized mothers losing their babies, and suffering from negative mood changes. In these last two papers, the authors suggest that the effects of DST are similar to those of shift-work, which has known multiple adverse effects on health and safety due to the mismatch between the body clock and the social/work clock. On the Monday after the DST transition, the known stock market weekend effect (i.e., a predictable negative influence on stock-trading each Monday morning), is augmented by 200–500% in several international markets, implying a $31 billion one-day loss in the United States markets alone… The chronic effects may be small on an individual level, but they accumulate over time in individuals and both across time and space in populations resulting in big effects, the costs of which can be assessed similarly to those of insufficient sleep. From a chronobiological perspective, chronic effects are very likely because, throughout the months of DST, body and social clocks are likely set to different time zones in most people… [W]hile activity profiles on work-free days seem to be relatively insensitive to the DST change hinting at no or very slow adjustment of daily activity rhythms to DST… [C]ortisol rhythms were found to be advanced by only 2 min during DST (not the 1 h corresponding to full adjustment)… [O]ur body clocks do not heed social clocks because body clocks are based on sun clocks and not political laws; political laws cannot determine health—they can only influence it for the better or worse. In the second study, the analysis of the three different states of DST in Russia (i.e., traditional switching, perennial DST and perennial Standard Time) found an increase in SJL during perennial DST. The same study also found a small decrease in winter depression symptoms during perennial Standard Time… [C]hronic negative effects have likely been acting throughout the months of DST. [T]hey would indicate a prior sleep debt during DST… [R]isks increase and longevity decreases from the eastern to the western border of time zones… ‘[A]n extra hour of natural light in the evening reduces sleep duration by an average of 19 min’ with significant effects on health (e.g., obesity, diabetes, cardiovascular diseases, and breast cancer) and on economic performance (per capita income)… Later sunset times are also associated with fewer hours of sleep, poorer academic performance, and lower wages… SJL is associated with adverse health effects: these include increased likelihood to be a smoker as well as higher caffeine and alcohol consumption; higher incidence of depression and other mood pathologies such as anxiety disorders and personality disorders; increased risk of metabolic disorders, such as obesity, metabolic syndrome and type II diabetes or increased insulin requirements in adolescent diabetes-type-I patients; higher rates of cardiovascular problems and cognitive performance and academic achievements… SJL and circadian disruption are strongly correlated with a reduction in sleep duration… SJL is characterized by a constant oscillation between under- and over-sleeping. Notably people suffering from less than 30 min of SJL get the longest sleep on workdays and sleep the least on their free days compared to those of other SJL categories… [S]leep deficiency is associated with the same health risks as DST, SJL and being a late chronotype, e.g., with metabolic pathologies, suggesting that the effects have common mechanisms, for which sleep debt could be a good candidate… [T]he scientific literature strongly argues against the switching between DST and Standard Time and even more so against adopting DST permanently. The latter would exaggerate all the effects described above beyond the simple extension of DST from approximately 8 months/year to 12 months/year… Perennial DST increases SJL prevalence even more, as described above… [T]here are still many people who ‘like their long evenings.’ But there is a solution to this problem: DST is simply a work-time arrangement, nothing more than a decision to go to school/work an hour earlier. As such, it is not a decision that should be made by the world, by unions of countries (e.g., the EU), or by individual countries, neither at the federal nor the state level. Work-time arrangements are decisions that a workforce could decide at the company level. Therefore, anyone who wants to spend more time at home in daylight after work should convince his/her company and co-workers to advance their start time during certain months of the year or even better: introduce flexibility for individual workers where possible to accommodate differences in personal biological and social requirements.”
- Roenneberg, Till; Wirz-Justice, Anna; Skene, Debra J; Ancoli-Israel, Sonia; Wright, Kenneth P; Dijk PhD FRSB FMedSci, Derk-Jan; Zee, Phyllis; Gorman, Michael R; Winnebeck, Eva C; Klerman, Elizabeth B (2019). “Why Should We Abolish Daylight Saving Time?”. Journal of Biological Rhythms. “Local and national governments around the world are currently considering the elimination of the annual switch to and from Daylight Saving Time (DST). As an international organization of scientists dedicated to studying circadian and other biological rhythms, the Society for Research on Biological Rhythms (SRBR) engaged experts in the field to write a Position Paper on the consequences of choosing to live on DST or Standard Time (ST). The authors take the position that, based on comparisons of large populations living in DST or ST or on western versus eastern edges of time zones, the advantages of permanent ST outweigh switching to DST annually or permanently. Four peer reviewers provided expert critiques of the initial submission, and the SRBR Executive Board approved the revised manuscript as a Position Paper to help educate the public in their evaluation of current legislative actions to end DST.”
- Watson MD MSc, Nathaniel F (2019). “Time to Show Leadership on the Daylight Saving Time Debate”. Journal of Clinical Sleep Medicine. “Why do politicians care about this issue? They point to energy savings and increased physical activity, but these assertions have been debunked… 84% of individuals polled wanted to stop changing clocks back and forth… [E]nacting permanent ST also solves the problem and is the healthier, more natural choice… [T]here is nothing in the Uniform Time Act of 1966 preventing states from simply going back to ST as a solution to the biannual clock change conundrum… The human circadian system simply does not adjust to DST. Sleep becomes disrupted, less efficient, and shortened. The incidence of acute myocardial infarction increases up to 29% and ischemic stroke increases 9% following DST-related time changes. Mental health is impaired and suicide increases following the DST shift… [W]orkplace injuries increase in number and severity following DST clock changes. DST is akin to dosing the population with a small amount of shift work due to misaligning the human circadian system with typical work schedules; we know shift work is associated with cardiovascular disease, metabolic dysfunction, and cancer. DST forces our biological clocks out of sync with the inexorable rising and setting of the sun (eg, the sun clock). The harmonious link between our biological clock and the sun clock has been crucial to human health and well-being for millennia… Almost 70% of the world is on ST, including Hawaii and most of the state of Arizona, indicating the international community understands the negative effect of DST on their health and well-being and rejects it. I strongly believe the United States should do the same.”
- Zick, Cathleen D (2013). “Does Daylight Savings Time Encourage Physical Activity?”. Journal of Physical Activity and Health. “[S]hifting 1 hour of daylight from morning to evening does not impact MVPA [(moderate-to-vigorous physical activity)]… DST may affect the choices people make about the timing and location of their sports/recreational activities, the potential for DST to serve as a broad-based intervention that encourages greater sports/recreation participation is not supported.”
- “Impact of Daylight Savings on Productivity” (ND). COFCO. “Not surprisingly, there are very significant health implications. We all know that when we are not sleeping well or not getting enough sleep, we tend to be more stressed and less able to handle the ups and downs of life with equanimity.”
- “Joint Statement to the EU Commission on DST” (2019). European Sleep Research Society.
- “SRBR Talking Points About Daylight Saving Time” (2019). Society for Research on Biological Rhythms. “DST leads to decreased exposure to morning sunlight… Our body’s internal biological clock needs exposure to morning sunlight to adjust to local time. When the exposure to sunlight in the morning is reduced, our biological clocks will drift later and later, making it harder to wake up… DST leads to sleep loss and a mismatch between the body clock and local time (also called social jetlag). Both sleep deprivation and social jetlag have negative effects on physical and mental health, including increased risks for diabetes, obesity, heart disease, depression, and some forms of cancer. Therefore, keeping DST during summer or all year round in the US, will have serious implications for public health and safety… DST means that we wake up in darkness and are exposed to more evening light, especially in the western parts of each of the time zones. Adhering to DST throughout the year would result in even more hours of morning darkness during winter for many people. This makes waking up more difficult for everyone, from school kids to adults, and is likely to worsen conditions such as seasonal affective disorders… Brighter days and darker nights are critical for a healthier population year round. Thus, DST should be abolished, and we as biological rhythms experts clearly favor permanent Standard Time (when the clock times matches sun times)… DST has not been shown to be responsible for more physical activity during the summer months. It is much more likely that the change in season is responsible for changes in physical activity patterns. It is also noteworthy that there is no direct evidence suggesting that permanent DST would be beneficial for physical activity during the winter months.
- “To the EU Commission on DST” (2018). European Biological Rhythms Society. “Chronobiology studies the influence of day–night rhythms and seasonal changes in living organisms (and received the Nobel Prize 2017 for these discoveries). As experts in biological clocks and sleep, we have been following the initiative of the European Commission to abandon the annual clock-time changes in spring and autumn in the EU. We would like to emphasize that the scientific evidence presently available indicates that installing permanent Standard Time (ST, or ‘wintertime’) is the best option for public health. With ST there will be more morning light exposure in winter and less evening light exposure in summer. This will better synchronise the biological clock and people will sleep earlier relative to their work and school times. The feeling of chronic jetlag (Social Jetlag) will be reduced compared to daylight savings time, the body will function better and mental performance will improve. Throughout the year, ST will be healthier than daylight savings time (DST). ST improves our sleep and will be healthier for our heart and our weight. The incidence of cancer will decrease, in addition to reduced alcohol and tobacco consumption. People will be psychologically healthier and performance at school and work will improve. Abandoning clock changes will offer the unique nation-wide opportunity to improve general health by installing Standard Time.”
- Achenbach, Joel (2019). “Springing Forward to Daylight Saving Time Is Obsolete, Confusing and Unhealthy, Critics Say”. Chicago Tribune. “There’s one massive objection to the idea of year-round DST: The already dark, cold mornings of fall and winter under standard time would become even darker and colder, and potentially dangerous for kids walking to the bus stop or to school. ‘National PTA is opposed to daylight saving time during the winter months because of the safety factor,’ said Heidi May Wilson, spokesperson for the National Parent Teacher Association.”
- Boynton, Donna (2015). “Deadly Car Crashes Spike After Changing Clocks for Daylight Saving Time”. Telegram.com. “[T]here were 302 deaths and a cost of $2.75 billion over a 10-year period…a 17 percent increase in traffic fatalities.”
- Merline, John (2018). “Time to Ditch Daylight Saving Time—It’s a Killer That Doesn’t Save Energy”. Investor’s Business Daily. “One of these studies, published in the Journal of Accident Analysis and Prevention, found that springing forward causes an extra 195 auto fatalities and 171 pedestrian deaths each year… Going permanently on daylight saving time might not be the solution, either. According to Ars Technica, Russia tried that a few years ago, and found that it gave people stress and health problems when it stayed darker for longer during winter mornings. So it ended up reverting to standard time, year round. Likewise, the U.S. tried year-round daylight saving time in 1974, and abandoned it after several children died in accidents during the winter months because they were going to school in the dark.”
- Smith, Austin C (2016). “Spring Forward at Your Own Risk: Daylight Saving Time and Fatal Vehicle Crashes”. American Economic Journal. “[M]otor vehicle crashes are the number one cause of accidental death in the United States… 5.6 percent increase in fatal crashes, persisting for six days following the spring transition. This suggests that the spring transition into DST is responsible for over 30 deaths annually at a social cost of $120 to $300 million. Additional back-of-the-envelope calculations imply that a 1-hour decrease in sleep duration increases the prevalence of fatigue related fatal crashes by 46 percent, underscoring the huge costs of even minor disruptions to sleep schedules given the current sleep-deprived culture in the United States. The total costs of DST due to sleep deprivation could be orders of magnitude larger when worker productivity is considered… [T]he spring transition into DST increases fatal crash risk by 5–6.5 percent… [S]leep deprivation is driving the increase in fatal crashes. Consistent with literature investigating the impact of DST transitions on sleep, the impact persists for the first six days of DST. Back-of-the-envelope calculations suggest that the spring transition into DST caused over 30 deaths annually at a social cost of $275 million… The results imply that a one hour sleep loss increases the probability of being in a drowsiness-related fatal crash by 46 percent.”
- “For Kids’ Sake, Vote No on Year-Round Daylight-Saving Time” (2018). The Mercury News. “The National Highway Traffic Safety Administration reports that 20 percent of the total number of pedestrians killed in traffic crashes are children up to 14 years old. It also notes that more than 70 percent of all pedestrians killed in traffic accidents occur when it is dark.”
Energy & Environment
- Albeck-Ripka, Livia (2018). “Daylight Saving Time Isn’t Saving Much Energy”. The New York Times. “[W]hen daylight time begins in spring, people are often waking up during ‘the coldest, darkest part of the day,’ and turning up heat to stay warm, said Matthew Kotchen, a professor of economics at Yale who led a 2008 study on the effectiveness of the policy in Indiana. During long evening hours in the summer, Dr. Kotchen added, people tended to ‘crank up the A.C.,’ leading to overall higher energy use.”
- Bambrick, Gail (2014). “Daylight Saving Time Does Not Save Energy”. Phys.org. “Gas consumption goes up during daylight saving time—’something the gas industry has known since the 1930s,’ Downing says. That’s why it lobbied hard to reintroduce DST after two short-term experiments with it to conserve electricity and other energy resources during World Wars I and II. But more driving also means more carbon dioxide in the atmosphere, which exacerbates climate change, says Downing. Moreover, the reduced cost of indoor lighting on sunny spring and summer afternoons is offset by higher air-conditioning costs at offices, factories and shopping malls. ‘Every time the government studies [DST], it turns out that we are really saving nothing when all is said and done.’”
- Block, Melissa (2007). “The Reasoning Behind Changing Daylight-Saving”. NPR. “Daylight Saving increases gasoline consumption, something the petroleum industry has known since 1930.”
- Cohen, Benyamin (2019). “Do We Still Need Daylight Saving Time?”. Mother Nature Network. “[G]asoline consumption increases every time we increase the length of the daylight saving period.”
- Handwerk, Brian (2013). “Daylight Saving Time 2013: When Does It End? And Why?”. National Geographic. “The researchers found that the practice [of extended daylight saving time in Australia] reduced lighting and electricity consumption in the evening but increased energy use in the now-dark mornings—wiping out the evening gains… [W]hen the whole state [of Indiana] adopted DST [in 2006], it became possible to compare before-and-after energy use. While use of artificial lights dropped, increased air-conditioning use more than offset any energy gains… [T]he extra hour that daylight saving time adds in the evening is a hotter hour. ‘So if people get home an hour earlier in a warmer house, they turn on their air conditioning’… [C]onsumers paid more on their electric bills than before they made the annual switch to daylight saving time.”
- Kotchen, Matthew J; Grant, Laura E (2008). “Does Daylight Saving Time Save Electricity?”. Centre for Economic Policy Research. “An early and oft-cited study by the US Department of Transportation (1975) found that DST causes a 1% decrease in electricity consumption at the points of transition in the spring and fall. But a subsequent evaluation of the study concludes that the results are statistically insignificant (Filliben 1976)… Rock (1997) finds that DST increases electricity consumption on average over 224 different locations throughout the US… Shimoda et al (2007) conduct a similar exercise that accounts for air-conditioning as well and find that DST results in a 0.13% increase in residential electricity consumption… Our main finding is that—contrary to the policy’s intent—DST increases residential electricity demand. Estimates of the overall increase are approximately 1%, but we find that the effect is not constant throughout the DST period. DST causes the greatest increase in electricity consumption in the late summer and early fall, when estimates range between 2% and 4%… We find that the policy costs Indiana households an average of $8.6 million per year in increased electricity bills. We also estimate social costs of increased pollution emissions due to the residential response to be between $1.6 and $5.3 million per year.”
- Kotchen, Matthew J; Grant, Laura E (2008). “Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana”. The National Bureau of Economic Research. “Our main finding is that—contrary to the policy’s intent—DST increases residential electricity demand. Estimates of the overall increase are approximately 1 percent, but we find that the effect is not constant throughout the DST period. DST causes the greatest increase in electricity consumption in the fall, when estimates range between 2 and 4 percent. These findings are consistent with simulation results that point to a tradeoff between reducing demand for lighting and increasing demand for heating and cooling. We estimate a cost of increased electricity bills to Indiana households of $9 million per year. We also estimate social costs of increased pollution emissions that range from $1.7 to $5.5 million per year. Finally, we argue that the effect is likely to be even stronger in other regions of the United States.”
- Porter, Catherine (2008). “Why Daylight Saving Time Is Bad for the Environment”. The Star. “In Indiana, people might not have been flipping on the lights when they returned home after work. But they were cranking their air conditioners, because that extra hour of evening sunlight meant another hour of ‘solar build-up on your house,’ says Kotchen. ‘Take an hour at dawn versus an hour at sunset. When do you think you’re going to run the air conditioner harder?’… He figures the air conditioning effect will be even more profound in southern states. And in the north, there is the opposite problem: waking up an hour earlier in the spring and fall means more time roaming around a cold house, rather than dozing under a duvet… On a hot summer day in Ontario, air conditioning can account for a quarter of our total electricity demand. Another way daylight savings might be fuelling our warming climate? Increased carbon dioxide fumes sputtering out of car tailpipes… [I]n the 1930s, the petroleum industry lobbied hard to reintroduce daylight savings.”
- Barnes, Christopher M; Wagner David T (2009). “Changing to Daylight Saving Time Cuts into Sleep and Increases Workplace Injuries”. Journal of Applied Psychology. “[O]n Mondays directly following the switch to Daylight Saving Time—in which 1 hr is lost—workers sustain more workplace injuries and injuries of greater severity… On Mondays directly following the switch to Standard Time—in which 1 hr is gained—there are no significant differences in sleep, injury quantity, or injury severity… Workplace injuries can lead to a host of problems for organizations, including lost productivity, legal action, turnover, and lost human capital. Workplace injuries also lower the quality of life of employees, may result in lost income, and in extreme cases can result in death… Following phase advances, employees slept 40 min less, had 5.7% more workplace injuries, and lost 67.6% more work days because of injuries than on non phase change days. Phase delays did not have any significant effects on sleep, injury frequency, or injury severity.”
- Gibson, Matthew; Shrader, Jeffrey (2015). “Time Use and Productivity: The Wage Returns to Sleep”. Williams College Department of Economics Working Papers. “[E]arlier sunset causes workers to begin sleeping earlier…this earlier bed time translates into more sleep… [C]omparing two locations in the same time zone, the location farther east will experience earlier average sunset than the location farther west. As a consequence, residents of the eastern location will sleep longer… [L]ater sunset times decrease wages. Intra-annually, a one-hour increase in sunset time decreases worker wages by 0.5%, while a one-hour difference in long-run average sunset time decreases worker wages by 4.5%… [A] short-run, one-hour increase in average weekly sleep increases worker wages by 1.5%. A permanent one-hour increase in weekly average sleep increases average wage by 4.9%… A one-hour increase in a location’s weekly mean sleep raises wages by roughly half as much as a one-year increase in education for all workers… [S]leep has a powerful impact on labor market outcomes… [I]ncreasing short-run weekly average sleep in a location by one hour increases worker wages by 1%. Increasing long-run weekly average sleep in a location by one hour increases wages by 4.5%… [S]leep is a crucial determinant of productivity, rivaling ability and human capital in importance.”
- Giuntella, Osea; Mazzonna, Fabrizio (2017). “Sunset Time and the Economic Effects of Social Jetlag Evidence from US Time Zone Borders”. Journal of Health Economics. “[A]n extra hour of natural light in the evening reduces sleep duration by an average of 19 minutes and increases the likelihood of reporting insufficient sleep… [D]iscontinuity in the timing of natural light has significant effects on health outcomes typically associated with circadian rhythms disruptions (e.g., obesity, diabetes, cardiovascular diseases, and breast cancer) and economic performance (per capita income)… As all mammals, humans respond to environmental light, the most important signal regulating our biological clock. However, human beings are the only animal species that deliberately tries to master nature, for instance depriving themselves of sleep. Individuals adjust their schedules responding to incentives to economic and social coordination. The inability to master the biological responses of our body gives rise to the health and human capital effects we estimate in this study. The timing of natural light is determined by the existence of time zones and has a direct effect on the sleep-wake cycle. The human body reacts to environmental light, producing more melatonin when it becomes darker. The misalignment of sleep and wake rhythms with the daily cycle of physiological processes desynchronizes the release of hormones such as melatonin, cortisol (‘the stress hormone’), ghrelin (the ‘hunger hormone’) and leptin (the ‘satiety hormone’). As these hormones are related to stress, metabolism and inflammation, circadian rhythms disruptions can directly affect health by increasing the risk of metabolic and cardiovascular diseases, and cancer progression. Medical studies provide evidence of important associations of exposure to artificial and natural light at night with sleep loss, weight gain, cognitive impairment and chronic diseases such as cardiovascular diseases, and diabetes. There is also observational evidence on shift workers and experimental evidence on rats suggesting that circadian rhythms disruption increases the risk of certain types of cancer… Because of the delayed onset of daylight and the biological link between environmental light and the production of melatonin throughout the day, individuals on the late sunset side of a time zone boundary will tend to go to bed at a later time… Thus, many individuals are not able to fully compensate in the morning by waking up at a later time… Yet, statistics suggest many of us sleep less than the recommended 7–8 hours. A survey conducted in 2013 by the U.S. National Sleep Foundation found that Americans are more sleep-starved than their peers abroad, and the Institute of Medicine (2006) estimates that 50–70 million US adults have sleep or wakefulness disorder. Estimates suggest that in many countries, individuals are sleeping as much as two hours less per night than did their ancestors one hundred years ago and that the ‘unnatural’ timing of sleep may be the ‘most prevalent high-risk behavior in modern society’… [E]mployed people living in counties on the late sunset side of the time zone border sleep on average 19 fewer minutes than employed people living in neighboring counties on the opposite side of the border because of the one-hour difference in sunset time. More generally, individuals on the late sunset side of a time zone boundary are more likely to be sleep deprived, more likely to sleep less than 6 hours, and less likely to sleep at least 8 hours. The effects are larger among individuals with early working schedules and among individuals with children of school age… [W]e also find evidence of significant discontinuities in the incidence of obesity, diabetes, cardiovascular diseases, and breast cancer. Summarizing these outcomes with a standardized composite health index, we find that living on the late sunset side of the border decreases the index by .3 standard deviations… [T]he reduction in sleep duration has been associated with the release of hormones that are correlated with weight gain and with inflammations associated with cardiovascular diseases and certain types of cancer… [T]he delay of natural light onset has significant effects on health outcomes… [H]ealth slightly improves in the short run (4 days) when clocks are set back by one hour in Fall… DST increases fatal crashes… [A] one-hour increase in average daily sleep increases productivity to a greater extent than does a one-year increase in education… [E]ven small differences in school start times can have large effects on academic outcomes… [I]ndividuals living on the late sunset side of a time zone boundary tend to go to bed later than do individuals living in the neighboring counties on the opposite side of the time zone border… [I]ndividuals on the late sunset side of the border do not fully compensate… [E]mployed individuals living on the late sunset side of a time zone border sleep less… [T]he effects are considerably larger among individuals with early working schedules. Furthermore, we find significant discontinuities in weight, diabetes, cardiovascular diseases, and certain types of cancer typically associated sleep deprivation and disruption to circadian rhythms… [W]ages tend to be 3% lower on the late sunset side of the time zone border, suggesting negative effects on economic productivity… [T]he circadian misalignment increases health care costs by at least 2.35 billion dollars (approximately $82 per capita, in 2017 $). Productivity losses associated with the insufficient sleep induced by the extra hour of light in the evening are equivalent to 4.40 million days of work (1.3 hours per capita), 612.9 million dollars ($23 per capita)… [I]ndividuals may have inaccurate self-perceptions of their biological needs and may underestimate the long-run effects of circadian rhythm disruption.”
- Wagner, David T (2014). “The Economic Toll of Daylight Saving Time”. The New York Times. “After the spring time change, there are more and worse workplace injuries, and workers tend to dawdle more on the Internet… [W]e found a spike in workplace injuries of nearly 6 percent on the Monday following the shift to daylight saving time. An even greater cause for concern is that the severity of these injuries, as measured by days of work lost because of the injuries, increased by a whopping 67 percent, representing 2,600 more workdays lost… [W]orkers tend to ‘cyberloaf’—that is, they use their computers and internet access to engage in activities that are not related to work—at a substantially higher rate on the Monday following the shift to daylight saving time than on other Mondays. What’s more, we found that for every hour of interrupted sleep the previous night, participants in our lab cyberloafed for 20 percent of their assigned task. When extrapolated to a full day’s work, that would mean daylight saving time and lost sleep can result in substantial productivity losses. In fact, a recent estimate of this effect put the cost to the American economy at over $434 million annually, simply from a subtle shift of the clocks. Unfortunately, we don’t regain that productivity when the fall change adds an hour to our schedules.”
- Wagner, David T; Barnes, Christopher M; Lim, Vivien KG; Ferris, D Lance (2012). “Lost Sleep and Cyberloafing: Evidence from the Laboratory and a Daylight Saving Time Quasi-Experiment”. Journal of Applied Psychology. “[A]n hour of disturbed sleep would on average result in cyberloafing during 20% of the assigned task… [T]he shift to DST leads people to cyberloaf…”
- Eller, Sandy (2018). “Florida’s Proposed Change to Permanent Daylight Savings Time Could Create Halachic Problems for Jewish Community”. Vos Iz Neias?. “[Year-round DST] could wreak havoc on morning minyanim, explained Rabbi Moshe Matz, executive director of Agudath Israel of Florida, with neitz hachama, the earliest time to daven Shmone Esrai, taking place as late as 8:05 [in Florida] during the winter. ‘If you are a worker or have to drive carpool you are going to need to rely on leniencies when it comes to davening,’ Rabbi Matz told VIN News. ‘There will be days when you won’t be able to even put on tallis and tefillin until after 7:30.’ The proposed changes would also create inconveniences for Florida’s Jewish community. ‘Because Shabbos will be finishing later, people who want to fly out of Florida on Motzei Shabbos will have trouble finding flights,’ observed Rabbi Matz. ‘Businesses and restaurants who earn much of their livelihood by opening up on Motzei Shabbos will lose significant amounts of business. And there will be many days when kids will be going to school when it is pitch dark outside, something we don’t have here now.’”
- “Orthodox Group Asks Congressman to Withdraw Year-Round Daylight Time Bill” (1972). Jewish Telegraph Agency. “[Y]ear-round daylight saving time would create a major problem for religious Jews. According to Jewish religious law, the earliest time for morning prayers is one hour before sunrise. As a result, during winter time, prayers cannot begin before 6:15 a.m. [in New York], the Agudath Israel officials explained. By advancing the clock one hour, the observant Jew would not be able to begin his morning prayers until 7:15 a.m. The Agudath Israel spokesmen said this would ‘create an anomalous situation for thousands of religious Jews who must be at work prior to 8 or 8:30 a.m.’”
- “Sunrise, Sunset, and Daylength” (ND). Time and Date AS.
- Ballard, Jamie (2019). “54% of Americans Would Support Ending Daylight Saving Time”. YouGov. “A majority (54%) say that they would support the elimination of Daylight Saving Time in all US states and territories… [O]ne-third of those that observe it (35%) say they prefer this part of Daylight Saving Time, often referred to as ‘springing forward,’ rather than the fall when the clocks are set back an hour and daylight hours become shorter (28%). This is often called ‘falling back’. Another 35% say they have no preference between the two.”
- Schreuer, Milan (2018). “EU Will Let Countries Decide Whether to Use Daylight Saving”. The New York Times. “Officials said that 84 percent of respondents wanted to end daylight saving, and three-quarters considered it a ‘negative’ experience, expressing concerns about health impacts, increased traffic accidents and a lack of proven energy savings.”
- Sistek, Scott (2019). “Killing Time (Changes): Better to Permanently Keep Daylight Saving Time? Or Standard Time?”. KOMO News. “The evidence has been becoming increasingly clear that any benefits from adding an hour in the summer is outweighed by the costs, both financial and healthwise, of having several days each year where everyone gets an instant case of jet lag… 67 percent would favor keeping their clocks on the same time year ‘round… But what gets left out in most of the discussions around Daylight Savings is the effect on the sunrises as well. Perhaps more critically, the sun wouldn’t rise until past 8 a.m. in the late fall and would be as late as nearly 9 a.m. for much of December and January. The sunrise wouldn't pull back earlier than 8:30 a.m. until Feb. 6, and not before 8 a.m. until Feb. 24. That’s sending a lot of elementary and middle school kids to school in the dark—and usually the gloomiest and rainiest months too. And probably the overriding factor of why I think we should stay on standard time than daylight time. 8:15 p.m. sunsets in summer are still plenty late and since it's usually the sunny and dry season, we get extended twilight hours with usually clear skies… If we were to get rid of the time change, what would you prefer? 47% ‘Stay on PST’, 41% ‘Stay on PDT’, 12% ‘Move up 30 mins instead’.”
- “2018 Official Endorsements November 6, 2018 Elections” (2018). California Democratic Party. “Prop 7: Support. YesProp7@gmail.com. One liners: Saves lives and money by stopping dangerous time changes. Proposition 7 is a required step in the process to stop the biannual time changes that harm health and safety of workers and their families. That’s why the California Democratic Party is recommending a Yes vote on Proposition 7.”
- “Just 33% See the Purpose of Daylight Saving Time” (2014). Rasmussen Reports. “Only 33% of American Adults think DST is worth the hassle… Forty-eight percent (48%) do not think the clock changing ritual is worth it, but 19% are not sure.”
- “Official Ballot – Consolidated General Election – City and County of San Francisco – November 6, 2018” (2018). San Francisco Department of Elections. “7. Conforms California Daylight Saving Time to Federal Law. Allows Legislature to Change Daylight Saving Time Period. Legislative Statute. Gives Legislature ability to change daylight saving time period by two-thirds vote, if changes are consistent with federal law. Fiscal Impact: This measure has no direct fiscal effect because changes to daylight saving time would depend on future actions by the Legislature and potentially the federal government.”
- “Residents Face Setbacks When It’s Time to Spring Forward” (2018). PEMCO Insurance. “[T]wo-thirds maintain that they'd prefer to keep clocks on the same time year-round.”
- “Summertime Consultation: 84% Want Europe to Stop Changing the Clock” (2018). European Commission. “84% of respondents are in favour of putting an end to the bi-annual clock change.”
Learn from History
- Clark, James C (2018). “Daylight Saving Year-Round: Once a Disaster, Always a Disaster”. Orlando Sentinel. “Millions of schoolchildren were going to school in pitch dark, which meant more 16-, 17- and 18-year old drivers on the road in darkness. Accidents soared and schools and parents protested. Eight months after he signed the legislation making daylight saving time permanent, Nixon resigned and soon after that Congress repealed the permanent daylight saving time law.”
- Downing, Michael (2005). “Endless Summer”. The New York Times. “This decision did not soften the blow of the OPEC oil embargo, but it did put school children on pitch-black streets every morning until the plan was scaled back.”
- Downing, Michael (2018). “One Hundred Years Later, the Madness of Daylight Saving Time Endures”. Smithsonian. “On Jan. 8, 1974, Richard Nixon forced Floridians and the entire nation into a year-round daylight saving—a vain attempt to stave off an energy crisis and lessen the impact of an OPEC oil embargo. But before the end of the first month of daylight saving that January, eight children died in traffic accidents in Florida.”
- Jenkins, Evan (1974). “Schools Ask End to Daylight Time”. The New York Times. “Such visits have combined with complaints from back home to prompt the movement on Capitol Hill for a reversion to standard time. Much pressure has come from Florida, where eight school‐age children have been killed in accidents since daylight time was imposed.”
- Ripley, Anthony (1974). “Senate Votes Return to Standard Time for Four Months and Sends Bill to Ford”. The New York Times. “[P]arents became concerned about traffic accidents involving their children, who were going to school in the predawn darkness on winter mornings… A study on public acceptance of daylight saving time was conducted by the National Opinion Research Center of the University of Chicago and showed that 79 per cent of those interviewed last December favored the daylight time move. This total dropped to 42 per cent in February… It also noted ‘a majority of the public’s distaste’ for daylight time during the darkest and coldest winter months.”
- Steade, Susan (2016). “The Year Daylight Saving Time Went Too Far”. The Mercury News. “By fall, the dark mornings were apparently wearing on the American people. Proclaiming ‘it’s for the children’—those scholars standing at bus stops in the predawn—lawmakers threw in the towel of gloom. Year-round DST was scrapped.”
- “British Summer Time: Why Do We Change the Clocks?” (2018). Yorkshire Evening Post. “Between 1968 and 1971 the clocks were changed to BST permanently as an experiment, but after complaints that it made Scotland too dark in the mornings, the sun didn’t rise until 9am, the Government reverted to using BST between March and October.”
- “Russia: Putin Abolishes ‘Daylight Savings’ Time Change” (2014). BBC News. “In 2011 he switched the clocks to year-round ‘summer time’. The change was initially popular, but a survey last year showed less than a third of Russians wanted to keep the clocks forward all year. MPs say permanent summer time created stress and health problems, especially for people in northern Russia where the mornings would remain darker for longer during the harsh winter months. They cited medical reports of increased morning road accidents in 2012 compared to previous years, and blamed them firmly on the 2011 time change.”
- Bryner, Jeanna (2019). “Daylight Saving Time 2019: A Guide to the When, Why, What, and How”. Live Science.
- Skeldon, Anne C; Dijk PhD FRSB FMedSci, Derk-Jan (2019). “School Start Times and Daylight Saving Time Confuse California Lawmakers”. Current Biology. “Adequate synchronisation of endogenous circadian rhythms to external time is beneficial for human health… [A] switch to permanent DST could negate any beneficial effects of delaying school start times.”
- Stoneham, Bray (2017). “Starting Work Before 10am Is Comparable to ‘Torture’, Study Reveals”. Australian Men’s Health.
- “The Equation of Time” (2017). The United States Naval Observatory.
- Craven, Scott (2019). “Daylight Saving Time Begins Sunday: Who Observes It, Will It Affect Health?”. Iowa City Press-Citizen. “While ditching daylight saving involves a state merely notifying the Department of Transportation, enacting it year-round is more involved, including approval by Congress. A state can not ‘permanently’ stay on daylight saving time under federal law, the DOT says… Congress has considered bills to allow states to remain on daylight saving time permanently, but they’ve stalled before legislators in either the House or Senate have had the chance to vote on them.”
- Skelton, George (2018). “Year-Round Daylight Saving Time? More Dark Mornings Is Just One Downside”. Los Angeles Times. “Brown was on target when he called it ‘a circuitous path.’ Converting to daylight saving all year would require a two-thirds majority vote in the Legislature and approval by Congress, plus signatures of the governor and president. California could stay on standard time all year without Washington’s OK, just as Arizona and Hawaii have… Chu says he doesn’t actually care whether California goes on year-round daylight saving or standard time. He just wants the state to pick one and stop switching clocks twice a year.”