Well-Being Prevention & Cures

Daylight saving time: Here are the biggest risks of the ‘spring forward’

Mornings will get darker for most Americans when the clocks change on March 12.

Story at a glance

  • Most of the United States is preparing to once again switch to daylight saving time.

  • Americans will lose an hour of sleep amid the change and face later sunrises for months to come.

  • Experts warn darker mornings can pose health and safety risks.

In the months to come, many Americans will be facing dark mornings — and with them, risks to their health and safety.

Clocks will shift forward in most of the U.S. on Sunday as daylight saving time begins, resulting in later sunrises and sunsets across the country.

Both sleep experts and motor vehicle organizations caution that darker mornings pose health risks and can heighten the threat of driver-related accidents.

To head off these risks, they recommend adjusting sleep schedules in the days before the change and making sure cars are as safe as possible to drive by checking headlights and tire pressure.

What risks are posed by darker mornings?

Some Americans may prefer lighter evenings so they can enjoy more sunlight after school or work, but research suggests sunnier mornings and darker evenings are better for people’s health. 

This is in part because such a schedule aligns better with humans’ natural circadian rhythms. 

“The way our circadian biology works out is that light in the morning actually helps us set our body clock to go to sleep at a normal hour at night,” explained James A. Rowley, who is a professor of medicine at Wayne State University’s School of Medicine and sits on the board of directors of the American Academy of Sleep Medicine.

“That doesn’t sound intuitive, but that’s just how it works, that we need light in the morning to help us fall asleep at night, and then the opposite is true — too much light in the evening can prevent us from falling asleep,” he said. 

Research has shown the “spring forward” is linked with an increased risk of heart attacks, strokes and mood disturbances. 

In the long term, daylight saving has also been associated with heart disease and diabetes, Rowley added. This is in part thanks to disruptions in sleep schedules.

“Plus, we’re not quite tracking the sun correctly when we’re on daylight saving time. So the cues are just off by an hour or so, and that can have long term effects,” he said.

On top of the health risks, data shows that traffic fatalities rise in the days immediately following the “spring forward,” with the effects being more pronounced in western locations within a time zone.

That could be because drivers take to the roads while drowsy, explained AAA spokesperson Andrew Gross. 

As opposed to being just tired or fatigued, AAA defines drowsiness as the state right before a person falls asleep, Gross explained in an interview with Changing America. Losing that single hour of sleep during the daylight saving time switch can throw some people off, he added.

“Drowsy drivers who have slept about five hours or less have the same crash risk as someone who was driving drunk. That’s how serious drowsy driving is,” Gross said. 

And the more you do it, the worse it gets. “If you’re drowsy and you’re driving down the road, you’re not going to get more awake as you drive; you’re just going to get sleepier and sleepier,” he explained. 

Along with the immediate risks posed by the “spring forward,” darker mornings can make it more dangerous for kids waiting for the bus or walking to school.

COVID-19 restrictions being lifted mean more children may be commuting to school during the days immediately following the time change this year than in recent years. 

“This is the time that you have to slow down and pay attention, which is tricky, because some of the drivers might be groggy,” said Gross. 

“Now is a great time to remind people before daylight savings time that they get a good night’s sleep the night before, kind of prepare, get themselves mentally aware that the time change is coming,” he added.

How to head off risks 

Sleep experts recommend going to sleep 20 to 30 minutes before one’s usual bedtime in the days leading up to the “spring forward,” “just so you’re used to it when it happens,” said Rowley. 

In addition, Gross recommends checking your headlights and tire pressure before the time change, and maybe scheduling routine maintenance for cars. 

“All the things you can do to make your car as safe as possible and make it as easy as possible for you to see other cars and see pedestrians and bicyclists and scooters. All of that will make your daily commute a lot safer,” he said. 

For those with early morning commutes or who may be drowsy on the way into work, Gross recommends taking a break from the wheel. This could involve pulling off to the side of the road, stopping at a rest stop, grabbing a cup of coffee or even taking a 15 minute nap. 

“Drowsy driving is not going to get better if you just stay behind the wheel and keep going,” he said. 

In the longer term, sleep experts, including the American Academy of Sleep Medicine, have continually pushed for scrapping time changes altogether and adopting a permanent standard time where clocks better align with the sun’s position year-round.

“Our bodies are designed for standard time,” said Rowley, which he noted permits less light in the evenings and more light in the mornings and allows us to fall asleep easier.

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