Medical experts are continuing to stress daylight saving time's health consequences – notably how time changes can throw off your sleep cycle.
"It's the same story every year," Dr. Sabra Abbott, a Northwestern Medicine physician and associate professor of neurology in the school's department of sleep medicine, told USA TODAY.
"We're dealing with competing clocks," Abbott said, pointing to how our bodies usually follow the sun and not the time on our phones. How long sunlight lasts each day depends on the season and where you are geographically – but daylight saving time moves us farther away from the "sun clock," experts say.
"During standard time, noon tends to be the point at which the sun is highest in the sky. But when we shift to daylight saving time, what happens is that relationship between the wall clock and the sun clock are clearly skewed," Abbott said.
That can result in less sleep.
Most people have a harder time waking up during daylight saving time – because the sky stays darker longer in the morning. In turn, many have difficulty falling asleep at night because light lasts later into the evening.
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Especially this time of year, right before daylight saving time ends, "the biggest problem is our internal clock doesn't know it's time to wake up," Dr. Jennifer Martin, president of the American Academy of Sleep Medicine, told USA TODAY.
The Department of Transportation, which oversees daylight saving time, says the practice saves energy, reduces crime and prevents traffic accidents. But many medical experts disagree – saying the health consequences of losing sleep outweigh the time change's potential benefits.
"The benefits are theoretical and the harms are proven," Martin said.
Of course, healthy sleep is essential. Previous studies, including some that look specifically into the health impacts of daylight saving time, have found that long term sleep deficiency is linked to increased risk of depression, substance use disorder, cardiovascular disease and more.
Citing these health consequences, the American Academy of Sleep Medicine issued a 2020 position statement calling for the U.S. to eliminate daylight savings time and adopt year-round standard time nationwide.
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Back up. How does daylight saving time work?
If you're in a one of the 48 states that currently practice daylight saving time, you change your "wall" clocks twice a year. In the spring, the annual period of daylight savings begins – with clocks jumping forward an hour ahead of standard time and staying on "daylight savings time" until mid-fall.
Right now, we're nearing the end of daylight saving time – with clocks across most of the country falling back an hour on Sunday.
Returning to standard time, as most of the U.S. does the first Sunday of November, is usually "the easier (time change) to adapt to, Abbott says, adding that she encourages people to "take advantage of that time to try to get a little bit of extra sleep."
Still, it can be an adjustment. Martin notes that people who already struggle with sleep issues, like insomnia, and parents with infants are particularly impacted.
"Most of us feel the disruption in the spring when we lose an hour of the nighttime – but even in the fall as we're switching back, some people have a hard time adjusting," Martin said. "It's sort of like having a little bit of jet lag twice a year."
What about the Sunshine Protection Act of 2021?
In March, the U.S. Senate passed the Sunshine Protection Act of 2021. If the bill becomes law, daylight saving time would be permanent in all but two states, Arizona and Hawaii, and a handful of U.S. territories – where standard time is used year round.
Advocates of adopting this legislation have pointed to the potential economic and safety benefits – including recent research that's suggested permanent daylight saving will bring significantly less deer-vehicle collisions. Still, studies report mixed results. Past research from the University of Colorado Boulder, for example, found a 6% spike in car accidents right after daylight saving's annual "spring forward."
From a medical standpoint, many experts again stress that adopting permanent standard time, not daylight time, is critical.
"We actually oppose the Sunshine Protection Act because of the potential health and safety risks associated with daylight savings time in the winter months," Martin said. "The highest risk, of course, will be in the northern states – where, in some metropolitan areas, sunrise won't occur until 9:30 in the morning or later... We think about students going to school (in the dark)."
Experts and historians have also noted that the U.S. has tried to switch to a permanent daylight savings time before – but it did not last.
Permanent daylight saving time? America tried it before ... and it didn't go well
Abbott adds that, while just about everyone wants to "get rid of the switch back and forth" that comes with two time changes each year, "the real question is, 'Which direction should we go?' ... From sleep and health perspective, the best route seems to be permanent standard time."
Contributing: Adrianna Rodriguez, USA TODAY.
This article originally appeared on USA TODAY: Can daylight saving time harm your sleep? Yes, medical experts say