10 Ways Daylight Saving Time Is Bad For Your Health


For many, Daylight Saving Time is a minor annoyance, potentially causing you to oversleep or be late to an appointment. But outside of having to manually update the microwave clock, many might not think that springing ahead is such a big deal. In reality, DST actually correlates with a wide range of serious, sometimes even fatal issues. From increasing the incidence of fatal car accidents to triggering heart attacks and strokes, the time change may be much, much worse than you realize. Here are 10 ways Daylight Saving Time is bad for your health.

It increases our risk of getting in a car accident.

While some research—like this 2004 study in Accident Analysis & Prevention—suggest Daylight Saving Time makes driving safer, the reality is more complicated than that. Research published in 2020 in the journal Current Biology found a spike in fatal car accidents in the U.S. during the workweek following the "spring forward" of Daylight Saving Time. This isn't some isolated example: The researchers, from the University of Colorado Boulder, reviewed accident data over two decades, including 732,000 accidents, and found that there was an average spike of 6 percent in fatal collisions during that week.

"Our study provides additional, rigorous evidence that the switch to Daylight Saving Time in spring leads to negative health and safety impacts," senior author Celine Vetter, assistant professor of integrative physiology at University of Colorado Boulder, said in a statement. "These effects on fatal traffic accidents are real, and these deaths can be prevented."

It ruins our sleep.

Losing that hour of sleep when the clocks jump ahead doesn't just cause slight annoyances of our set schedule—it can disrupt our sleep for a week or more, resulting in all sorts of other declines in cognitive function. One study of high school students, published in the Journal of Clinical Sleep Medicine in 2015, found that during the entire week following the shift to DST, the teens slept about 2.5 hours less than the week before.

It messes with our biological clock over the long term.

Many assume that Daylight Saving simply disrupts our schedule for a day or two at most. But researchers have found that both the "spring forward" and "fall back" can impact us long after we've gotten used to the time change.

"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," Beth Ann Malow, MD, professor of Neurology and Pediatrics in the Sleep Disorders Division at Vanderbilt University Medical Center, said in a statement.

In 2019, Malow and her colleagues published commentary in JAMA Neurology that recapped epidemiological studies advocating the end of Daylight Saving Time. It laid out how DST's changes disrupt circadian rhythms—and, for example, can affect children with autism for weeks or even months.

"It's not one hour twice a year," added Malow. "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."

It makes us more likely to have a stroke .

Turning the clock ahead (and back) may increase your risk of a stroke. In a preliminary study released at the American Academy of Neurology's Annual Meeting in 2016, researchers from the University of Turku found that during the first two days following Daylight Saving Time transition, the rate of ischemic stroke jumped an average of 8 percent. Drawing on a decade of data, the research compared the rate of stroke in more than 3,000 people hospitalized during the week after DST transition to 11,801 people hospitalized two weeks before or two weeks after the transition week. But the findings also noted that after those first two days, there was no discernible difference in rates.

It affects our heart health .

It's not only strokes: A March 2013 article published in The American Journal of Cardiology found that incidences of heart attacks were also slightly higher in the week after the switch to Daylight Saving.

A separate Swedish study, published in The New England Journal of Medicine in 2008, also found an increase in the risk of heart attacks the first three weekdays following DST.

It may increase incidences of miscarriages.

Researchers from Boston University Medical Center found that miscarriage rates rose significantly in those who had become pregnant with in vitro fertilization during the first three weeks after DST goes into effect. Their findings, published in 2017 in Chronobiology International, specifically found that rates of loss were higher when DST occurred after embryo transfer.

It leads us to waste more time surfing the internet.

Stop beating yourself up about wasting so much time on social media and mindlessly jumping from one website to another—and start blaming Daylight Saving Time. According to 2012 research published in the Journal of Applied Psychology, the shift to Daylight Saving Time "results in a dramatic increase in cyberloafing behavior at the national level." The researchers determined this by drawing on Google data to track patterns in internet surfing the Monday after the transition to DST, attributing the rise to a loss of self-control due to sleep deprivation. And if you haven't heard, too much screen time is bad for your health.

It makes injuries more likely.

Believe it or not, a little extra sunlight could make you a lot less safe at work. According to a significant 2009 study published in the Journal of Applied Psychology, workplace injuries actually increase during Daylight Saving Time, primarily as a result of sleep deprivation. So much for daytime being safer.

It may lead to a rise in the suicide rate among men.

DST may even impact suicide rates, according to a notable Australian study published in the journal Sleep and Biological Rhythms in 2008. Examining suicide data from 1971 to 2001, the researchers found an increase in male suicide rates in the weeks following the kickoff of Daylight Saving Time in March.

It increases headaches.

Not only does DST cause figurative headaches in the form of overslept alarms and missed appointments—it has also been found to quite literally be associated with an increase in cluster headaches. As the UCI Health Center for Pain & Wellness explains, "The time change can disrupt sleeping schedules. Poor sleep and sleep deprivation may trigger migraines in patients who are predisposed to having them."

Additional reporting by Bob Larkin