'Spring forward' to daylight saving time brings surge in fatal car crashes
Deadly accidents spike 6% in week after time change
January 30, 2020
Science Daily/University of Colorado at Boulder
A study of 732,000 accidents over two decades has found that the annual switch to daylight saving time is associated with a 6% increase in fatal car crashes that week.
Fatal car accidents in the United States spike by 6% during the workweek following the "spring forward" to daylight saving time, resulting in about 28 additional deaths each year, according to new University of Colorado Boulder research.
The study, published January 30 in the journal Current Biology, also found that the farther west a person lives in his or her time zone, the higher their risk of a deadly crash that week.
"Our study provides additional, rigorous evidence that the switch to daylight saving time in spring leads to negative health and safety impacts," said senior author Celine Vetter, assistant professor of integrative physiology. "These effects on fatal traffic accidents are real, and these deaths can be prevented."
The findings come at a time when numerous states, including Oregon, Washington, California and Florida, are considering doing away with the switch entirely, and mounting research is showing spikes in heart attacks, strokes, workplace injuries and other problems in the days following the time change.
For the study -- the largest and most detailed to date to assess the relationship between the time change and fatal motor vehicle accidents -- the researchers analyzed 732,835 accidents recorded through the U.S. Fatality Analysis Reporting System from 1996 to 2017. They excluded Arizona and Indiana, where Daylight Savings Time was not consistently observed.
After controlling for factors like year, season and day of the week, they found a consistent rise in fatal accidents in the week following the spring time change. Notably, that spike moved in 2007, when the Energy Policy Act extended daylight saving time to begin on the second Sunday of March instead of the first Sunday in April.
"Prior to 2007, we saw the risk increase in April, and when daylight saving time moved to March, so did the risk increase," said Vetter. "That gave us even more confidence that the risk increase we observe is indeed attributable to the daylight saving time switch, and not something else."
With the arrival March 9 of daylight saving time, clocks shift forward by one hour, and many people will miss out on sleep and drive to work in darkness -- both factors that can contribute to crashes.
Those on the western edge of their time zone, in places like Amarillo, Texas, and St. George, Utah, already get less sleep on average than their counterparts in the east -- about 19 minutes less per day, research shows -- because the sun rises and sets later but they still have to be at work when everyone else does.
"They already tend to be more misaligned and sleep-deprived, and when you transition to daylight saving time it makes things worse," said first author Josef Fritz, a postdoctoral researcher in the Department of Integrative Physiology. In such western regions, the spike in fatal accidents was more than 8%, the study found.
The increase kicks in right away, on the Sunday when the clocks spring forward, and the bulk of the additional fatal accidents that week occur in the morning.
Changes in accident patterns also occur after the "fall back" time change, the study showed, with a decline in morning accidents and a spike in the evening, when darkness comes sooner.
Because they balance each other out, there is no overall change in accidents during the "fall back" week.
In all, over the course of the 22 years of data analyzed, about 627 people died in fatal car accidents associated with the spring shift to Daylight Savings Time, the study estimated.
Because the data only include the most severe of car accidents, the authors believe the results underestimate the true risk increase to drivers when time springs forward.
"Our results support the theory that abolishing time changes completely would improve public health," said Vetter. "But where do we head from here? Do we go to permanent standard time or permanent daylight saving time?"
Generally speaking, research has shown, it's better for sleep, the body clock, and overall health to have more morning light and less evening light, as is the case under standard time. Under permanent daylight saving time, mornings would stay dark later in winter all over the country, with the western parts of each time zone seeing the sun the latest, Vetter noted.
"As a circadian biologist, my clear preference is toward standard time."
https://www.sciencedaily.com/releases/2020/01/200130144410.htm
Daylight Saving Time has long-term effects on health
November 4, 2019
Science Daily/Vanderbilt University Medical Center
The annual transition to and from daylight saving time (DST) has clinical implications that last longer than the days where clocks "fall back" or "spring forward."
Over time, DST eliminates bright morning light that critically synchronizes biologic clocks, which can be associated with increased risk of heart attack and ischemic stroke, as well as other negative effects of partial sleep deprivation.
Average sleep duration shrinks by 15 to 20 minutes for adults during DST transitions, which may also increase the risk of fatal accidents.
"People think the one-hour transition is no big deal, that they can get over this in a day, but what they don't realize is their biological clock is out of sync," said Beth Ann Malow, MD, Burry Chair in Cognitive Childhood Development, and professor of Neurology and Pediatrics in the Sleep Disorders Division at Vanderbilt University Medical Center.
"It's not one hour twice a year. It's a misalignment of our biologic clocks for eight months of the year. When we talk about DST and the relationship to light, we are talking about profound impacts on the biological clock, which is a structure rooted in the brain. It impacts brain functions such as energy levels and alertness," she said.
Malow and colleagues published a JAMA Neurology commentary today recapping large epidemiological studies that advocate for ending the practice of setting clocks forward or back.
Some people may have more flexible circadian rhythms and adjust quickly while others are more sensitive. Malow, an expert on autism and sleep, said that the transition impacts some children with autism for weeks or months.
While the sleep and circadian communities believe returning to standard time may be more biologically appropriate, gaining political buy-in for a nationwide change remains a challenge. State legislation is "all over the map," with some states considering a return to standard time and others in favor of permanent DST. Tennessee has passed legislation supporting permanent DST, although such a change would require action from the U.S. Congress
https://www.sciencedaily.com/releases/2019/11/191104144133.htm
Debate on daylight saving time and school start time
April 22, 2019
Science Daily/University of Surrey
A switch to permanent daylight saving time will undo any positive effects on sleep of delaying school start times, according to researchers from the University of Surrey.
Writing in the journal Current Biology, Professor Anne Skeldon and Professor Derk-Jan Dijk discuss proposals by the California state legislature to introduce permanent daylight saving time (DST) and how this switch could undermine a 2018 vote in the state to delay school start time for teenagers. The vote last year in the California legislature, currently vetoed by the State Governor, prohibited the start of schools before 8:30am in a bid to improve student health and boost graduation rates.
Delaying school times has been a contentious issue in North America and Europe with proponents arguing that such a postponement would enable teenagers, who typically go to bed later, to get the recommended amount of sleep, whilst opponents point to the logistical problems that would arise from such a change. DST, the practice of setting the clocks forward one hour from standard time (ST) during the summer months in order to make better use of natural daylight, is also a divisive issue. In March, the European parliament voted to stop changing the clocks, with European Union member states required to decide whether to stay on permanent DST or permanent ST by 2021. California, Florida and Washington are all due to vote on whether to stay on permanent DST. Skeldon and Dijk point out that a switch to permanent DST is incompatible with the aims of delaying school times.
They note that a later biological wake time under permanent DST undermines the benefits of delaying school start times on the sleep of teenagers. For example, from a biological perspective, teenagers would find it as hard to get up at 7am under DST as getting up at 6am during. Skeldon and Dijk conclude that the introduction of permanent DST and delaying school start times are contradictory, as teenagers would, on average, lose any sleep benefit gained from a later school start time as a result of the shift to permanent DST, meaning they'd still be getting inadequate levels of sleep.
Professor Skeldon, from the Department of Mathematics, said: "Each spring, altering the clocks prompts debate. We enjoy the sudden change to lighter evenings, but we do not find the shift to our schedules easy. However, for our sleep, permanent DST is not the solution. Setting our clocks to DST during the winter month's means that the sun will appear to rise one hour later, leaving even more of us to get up in the hours of darkness. Of course, for those who live predominantly inside, rarely experiencing natural light, a switch to permanent DST will have less of an impact. But these people will also only see limited benefits from delaying school/work start times.
"It is complicated, but the impact of switching to permanent daylight saving time on adolescent sleep appears to have been neglected in these considerations."
Professor Dijk, Director of the Surrey Sleep Research Centre, commented: "Many of us are confused about clock and circadian time, but for the sake of our health and well-being it is about time we get our heads around it."
https://www.sciencedaily.com/releases/2019/04/190422112809.htm