Your body on daylight saving time: What you need to know when we 'spring forward'

Daylight saving time, happening this year on March 8, 2020, can cause mental and physical problems. (Photo: Getty Images)

Daylight Saving Time (DST) starts at 2 a.m. on Sunday, March 8, when we set the clocks forward and lose one hour of sleep. And while the centuries-old practice allows us to enjoy the sunlight more (we’ll do it again on Nov. 1, setting the clocks back to reclaim that hour), it messes with our wellbeing.

Why is “springing forward” so impactful? “Most people don’t have an hour to spare,” Rafael Pelayo, MD, clinical professor of the Sleep Medicine Division at Stanford University’s School of Medicine, tells Yahoo Lifestyle. “America is sleep-deprived to begin with, so losing that hour disrupts the length and quality of rest.”

REM, the phase of sleep where dreams happen and memory and learning function form, occurs during the last third of the night, says Pelayo. An additional disruption interferes with circadian rhythms (our evolutionary instinct to detect dawn or dusk) and makes us sleepier and disoriented. Here’s more on why daylight saving time can be difficult.

Driving becomes more dangerous

In January, a Current Biology study of 732,835 U.S. accidents from 1996 to 2017 found that fatal car accidents increased by 6 percent (28 deaths per year) during the week of the time change, due to fatigue and driving in the dark.

The study found that the farther west a person lives, the likelier they are to be involved in a deadly crash, because those in western regions experience more circadian disruptions due to the sun rising later in the day.

Study author Celine Vetter, assistant professor of integrative physiology at the University of Colorado Boulder, was not available to comment on the study for Yahoo Lifestyle. She told ScienceDaily, "Our study provides additional, rigorous evidence that the switch to daylight saving time in spring leads to negative health and safety impacts. These effects on fatal traffic accidents are real, and these deaths can be prevented."

You might be distracted at work

Watch your internet habits on the Monday after DST — that’s when people spend more time on Facebook, YouTube and ESPN, says a study published in the Journal of Applied Psychology. These entertainment-based inquiries — dubbed “cyberloafing” by researchers — had “considerably” higher search volume on the Mondays after the time change. “One limitation is that we don’t know for sure whether people were at work or whether their entertainment searches were work-related,” study author Chris Barnes, Ph.D., associate professor of management at the University of Washington, tells Yahoo Lifestyle.

A separate study conducted by Facebook in 2014 found a “significantly increased usage” of the word “tired” written in posts the week of the time change, along with spikes in the words "sleepy" and "exhausted.”

Workplace injuries are more common

Losing that hour can be dangerous if you work in a job that requires physical labor, found a 2009 study from the Journal of Applied Psychology. Barnes, who authored the study, examined half a million injuries among mine workers over a period of five years and concluded that on the Monday after DST — “Sleepy Monday” — injuries increase by more than 5 percent and are more severe. “The ability to control intention, make decisions and focus on tasks suffers that day because sleep deprivation affects the brain’s prefrontal cortex,” Barnes tells Yahoo Lifestyle. But in the fall, when the clocks are set back, there are no major differences in the number or degree of injuries.

Your heart attack risk rises

There’s a 24 percent increase in the number of heart attacks on the Monday after the clocks change, according to a study published in the BMJ journal Open Heart, compared to a 21 percent reduction on the Tuesday after we change the clocks back.

Study author Amneet Sandhu, M.D., assistant professor of medicine-cardiology at the University of Colorado Denver, was not immediately available for comment for Yahoo Lifestyle. He told ScienceDaily, "What's interesting is that the total number of heart attacks didn't change the week after daylight saving time. But these events were much more frequent the Monday after the spring time change and then tapered off over the other days of the week. It may mean that people who are already vulnerable to heart disease may be at greater risk right after sudden time changes."

Another piece of research found a 10 percent increase in heart attacks on the Monday and Tuesday following the time change. That risk declines by 10 percent in November. Study author Martin E. Young of the Division of Cardiovascular Diseases at the University of Alabama, Birmingham (who did not respond to Yahoo Lifestyle’s interview request) said in a press release, “Exactly why this happens is not known but there are several theories. Sleep deprivation, the body’s circadian clock and immune responses all can come into play when considering reasons that changing the time by an hour can be detrimental to someone’s health.”

You might miss a doctor’s appointment

People are significantly more likely to miss their scheduled doctor’s visit during the week of DST in March, found a study of more than two million medical appointments published in The Journal of Biological and Medical Rhythm Research. The reverse was true when transitioning out of DST in November. Researchers guessed that disrupted sleep patterns could throw people off, but acknowledged that reasons for non-attendance weren’t known.

All that said, for the states that participate (Hawaii and most of Arizona opt out) there are advantages to changing the clock in March: People can enjoy more outdoor activities, for example, and there is a 2.9 percent reduction in criminal assault on the subsequent Monday (lethargy doesn’t motivate criminals, said the researcher), while robbery rates for the day fall by 7 percent.

According to the National Sleep Foundation, you can ease into the transition by going to bed about 20 minutes earlier each night leading up to the change, and trying sleeping in an extra 30 minutes on the first morning of the time change.

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