How Daylight Saving Time Can Mess With Your Sleep
Daylight saving time promised positive benefits when it was established across most of the U.S. in 1966. It was designed to give people more usable hours of daylight, which could help conserve energy, boost health and stimulate the economy. Sounds pretty good, right?
Not so fast. Adjusting the clocks biannually—daylight saving time starts on the second Sunday of March and ends on the first Sunday of November—can do more harm than just leaving us groggy for a couple of days. It can disrupt sleep for months in some individuals, warns Stephanie Griggs, Ph.D., a sleep researcher and assistant professor at Case Western Reserve University’s Frances Payne Bolton School of Nursing.
“Shifting our sleep by an hour might not seem like much, but to our bodies, that’s a significant amount of time. People can come into a state of circadian misalignment,” she says.
In fact, daylight saving time is so bad for our sleep, major medical organizations—including the American Medical Association and the American Academy of Sleep Medicine (AASM)—have called for a permanent end to the practice.
As daylight saving time ends this Sunday, November 5, 2023, at 2 a.m., here’s a look at how daylight saving time can wreck your sleep and why many policymakers, as well as experts, want it eliminated.
How Daylight Saving Time Messes With Our Sleep
Light and darkness play a big role in regulating the circadian rhythm responsible for keeping us awake or asleep. Our circadian rhythm follows the 24-hour day-to-night cycle, often using light exposure to know when to trigger biological processes that make us feel alert in the morning and sleepy around bedtime.
Our circadian rhythm can naturally adjust with the gradual shifts in light we experience throughout the year. But when we adjust the clocks in the spring and fall for daylight saving time and standard time, we experience an abrupt shift in light exposure that can throw things off.
“When we have shorter days, and it gets dark earlier, our brain gets the signal to release melatonin,” explains Lina Begdache, Ph.D., associate professor at Decker College of Nursing and Health Sciences at the State University of New York at Binghamton. “We start feeling tired and sleepy, starting in the late afternoon.”
How the Start of Daylight Saving Time Impacts Sleep
When the clocks spring forward, meaning that we lose an hour, at the start of daylight saving time, we might feel too alert at our usual bedtime, which can lead to lost sleep or even sleep deprivation. “Sleep pressure builds throughout the day—it’s lowest in the morning, and highest at night around your typical bedtime,” Griggs explains. “If you don’t have enough sleep pressure that you would normally have at bedtime, your body won’t be ready for sleep.”
A 2015 study on high school students found that, during the week following the switch in the spring, teens slept an average of 32 minutes fewer per weeknight, adding up to a total of 2 hours and 42 minutes of lost slumber.
That lost sleep, combined with a wake-up time that feels even earlier than what the clock says, can leave us feeling tired all day long.
How the End of Daylight Saving Time Impacts Sleep
Unfortunately, things don’t look much brighter in the fall, even though shifting the clocks back an hour is often thought of as gaining an extra hour of sleep. A 2023 study of more than 30,000 participants found that people experienced twice the risk of having trouble falling asleep, and a 64% increase in difficulty remaining asleep in the week immediately after the transition back to standard time compared to the week prior. They also faced double the risk of excessive sleepiness during the daytime.
For most people, the effects of moving into or out of daylight saving time last between five and seven days, according to research analyzed by the AASM. But some people—particularly those who tend to sleep less than the recommended minimum of seven hours—may feel the effects for even longer, says Griggs.
“Adjusting the clocks is a lot more difficult to adjust to if you are already running a sleep debit. Over time, this can catch up with you and affect your health,” she says.
Will Daylight Saving Time Be Eliminated?
Given how disruptive daylight saving time can be for our sleep, it’s not surprising that 64% of Americans are in favor of eliminating seasonal time changes, per a survey conducted by the AASM. Their dreams of keeping a consistent time throughout the year seemed like they could become reality in March 2022, when the U.S. Senate unanimously passed the Sunshine Protection Act to make daylight saving time permanent.
While the AASM had advocated for adopting permanent standard time, which more closely aligns with our body’s internal clock, ending the seasonal time change by making daylight saving time permanent could be a step in the right direction for our sleep.
“This is second-best to being on permanent standard time,” Griggs notes. “The problem is really in the switching of the clocks.”
Despite the momentum, the bill that would end the changing of the clocks has since stalled, so we’ll still be practicing spring forward and fall back for the foreseeable future.
Tips for Better Sleep When Adjusting to Daylight Saving Time Ending
The best thing you can do to adjust to the switch between daylight saving time and standard time is to make the time change less abrupt. Rather than jumping by an hour in a single night, gradually shift your bedtime and wake-up time over the course of a week or two, says Griggs.
“Experts recommend no more than a 15-to-30-minute shift per night, and do that over time,” she explains. “When we do interventions with people to extend or restrict their sleep, we start in small increments until the person is achieving enough sleep, but avoid shifting things too much to majorly affect any body system.”
Another tip: Double down on your sleep hygiene practices. That includes keeping your bedroom relatively cool, quiet, and as dark as possible. Squeeze in some exercise during the day, which can help you drift off more easily at night. And be mindful about using smartphones and other blue light-emitting devices in the last couple of hours before bedtime.
“Blue light signals to the brain that it’s still daylight,” says Begdache.
If the shift in wake-up time has you feeling especially groggy in the morning, try to get a blast of bright light shortly after your alarm goes off, advises Griggs. That can help signal to the brain that it’s time to be alert.
“We recommend natural sunlight or a 10,000-lux lamp, which is good for depression and seasonal affective disorder in the winter,” she says. “You could also install brighter lights in your bathroom.”
Finally, try not to overdo it on caffeine during the day, even if you’re feeling a little tired in the afternoon. Afternoon fatigue could drive many people to reach for an afternoon pick-me-up, like a cup of coffee, which could continue to throw off your sleep once bedtime rolls around, and compound the sleep problems that come from adjusting the clocks.
“Caffeine can disrupt sleep, shorten the sleep cycle, and disrupt the structure of sleep,” warns Begdache. “People have less restful nights when they drink caffeine.”
Same goes for alcohol at night, tempting as it might be to reach for a nightcap to help you wind down at bedtime that’s an hour earlier than you’re used to.
“Alcohol may help people sleep initially, but they end up having disrupted sleep,” says Begdache. “It becomes a vicious cycle of not sleeping well and using substances to sleep better.”