The Extra Hour From the Fall Time Change May Mean Less Sleep

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Every November, you experience time travel and jet lag without getting on an airplane or, of course, actually time traveling. That's right, the first Sunday in November marks the end of daylight saving time, when much of the Western world turns its clocks back by one hour to return to standard time.

In the days that follow, you might find yourself asking: Why, despite gaining an hour, do I feel more tired or lethargic than usual, and how do I get back to normal? We're here to help.

What Is Daylight Saving Time?

The idea behind daylight saving time (DST) is to have darkness fall at a later clock time during the spring and summer, which gives people an extra hour of daylight while the weather is warm. 

In the United States, DST starts on the second Sunday in March, when we “spring forward” by setting our clocks one hour ahead of standard time. It ends on the first Sunday in November as we “fall back” by setting our clocks back one hour to standard time. 

Historically, this twice-yearly one-hour change in local time has been seen as benign. But is it?

The Effects of Daylight Saving Time on Sleep 

The body experiences time change as a kind of jet lag. When your internal clock suddenly doesn’t line up with the numbers on the clocks around you, circadian misalignment can become a real problem. 

The twice-yearly time changes associated with daylight saving time can throw off your circadian rhythm and make it harder to get sufficient sleep, which can lead to sleep debt. 

Although ostensibly we lose only one hour of sleep on the second Saturday in March as DST goes into effect, studies show we’re more likely to have difficulty falling asleep and/or staying asleep and experience a cumulative sleep loss over the next seven days. And it can take four weeks or longer for our bodies to adjust to the time change. Even with the fall time change, when we supposedly “gain” an hour of sleep, it’s not uncommon to experience a net sleep loss over the next week (more on that later). 

According to sleep scientist Matt Walker, these shifts in and out of DST are a “global experiment” that proves even one-hour changes in the sleep you get on a single night can have drastic impacts. 

The Effects of Daylight Saving Time Vary by Season 

The negative effects of daylight saving time changes often ripple out into bigger problems for public health and public safety. In addition to increases in traffic accidents and fatal car accidents, researchers report a higher incidence of workplace injuries as well as an uptick in cardiovascular and neurology-related risks in the days immediately following the start of daylight saving time in March. 

Taken together, these effects highlight the importance and fragility of our sleep health. It begs the question: If a one-hour change in sleep time is enough to hasten a heart attack in someone with heart problems, what other perhaps undetected health issues are being exacerbated by the loss of just one hour of sleep?

On the flip side of these scary statistics, in the days following the change back to standard time in the fall, incidences of stroke, heart attack, and traffic accidents fall to below normal levels. It’s like seeing in real time — and on a large scale — the incredible benefits of catching up on sleep.

How to “Fall Back” and Still Come Out Ahead

Do you feel more alert and in a better mood in the week after DST ends in November? Turns out there’s research to support the validity of those improvements. The autumn time change can also help you experience what it feels like to pay down debt without even trying. Those good feelings might inspire you to make getting enough sleep a priority moving forward. 

Because you’re gaining an hour of sleep, the November shift out of DST is easier to adapt to as compared to the March shift into DST. But it’s still important to be smart about the transition. 

Without preparation (transitioning in advance), it can take up to two weeks to adjust to the November time change, depending on how often you have to use an alarm clock to wake up for work, school, or other obligations. You might be able to adjust your sleep in just one week on free days, but it can take up to two weeks on work days. 

Here are some ideas for a smooth transition into the November time change.

• Go in Low: Reducing or keeping your sleep debt low (below 5 hours) going into the autumn time change will make the transition easier. ‍
• Ease in Gradually: To mitigate DST-induced social jet lag, take the few nights before the end of DST on the first Sunday in November to move your bedtime and wake time back by 15 minutes. ‍
• Work With Your Chronotype: Are you an early bird or a night owl? Your chronotype indicates your genetic predisposition to earlier or later bedtimes and wake times. As it turns out, early birds have an easier time adjusting to the “spring forward” time change. But it’s not so easy for night owls, as it can take up to eight weeks for their sleep to return to normal (there's evidence to suggest some never actually adjust!)! Interestingly, there seems to be less difference in the ways the early and late chronotypes handle the “fall back” time change, although some research indicates the fall transition is more challenging for early birds. If that’s you, prioritizing a slow transition to the new time change and keeping your sleep debt low will help you feel your best come the shift.  ‍
• Take the Full Hour: Because we’re setting our clocks back an hour, the first Sunday in November is a golden opportunity to pay down sleep debt. But research shows that most people don’t take full advantage of it, getting on average only about 40 minutes of extra sleep. It’s important to get the full hour to make up for the sleep you’ll likely lose during the days following the time change. While sleep loss when you’ve gained an hour may seem paradoxical, it's due to an increase in spontaneous awakenings as well as earlier rise times as your body adjusts. ‍
• Be Strategic About Your Light Exposure: The timing of your light exposure is especially crucial during the winter months. Shorter days, less bright sunlight, and more time under electric light indoors can throw off the timing of our normal sleep/wake cycle, affecting our energy levels. Get sunlight on your skin in the first 30 minutes after waking, and avoid or dim indoor electric light — or wear blue light-blocking glasses — in the 90 minutes before bed.‍
• Prioritize Sleep Hygiene: Focusing on your sleep hygiene is always in season, but it's especially important as DST ends and through the winter months. From being careful about the timing of your caffeine and alcohol consumption to taking time to wind down at night and keeping your bedroom cool, dark, and quiet -- your daily habits have a big impact on your sleep and energy. 

Make the Most of the Changing Time 

If there’s one thing we can learn from all of the research on the effects of daylight saving time, it’s how pivotal and fragile our sleep schedules are. When we see the dramatic negative impacts of shifting our social clocks “just one hour” every six months, we may start to question the sleep-disrupting changes that are part of daily life. From personal and professional obligations to bedtime procrastination, shift work, and travel across time zones — skimping on sleep and throwing your circadian rhythm a curveball can have serious consequences. 

It’s hard to ignore the deleterious effects of DST time changes, but for now, most of us will have to make the best of a less-than-ideal situation. Keeping your sleep debt low, being especially strategic about your fall and winter light exposure — and maintaining overall good sleep hygiene — are your best bets for getting your sleep and circadian rhythm back to normal after we set our clocks back in the fall. 

And RISE can help. Use RISE to help you keep track of your sleep debt, transition your energy schedule in advance of DST, and build or stick to your sleep hygiene habits and routine. Because no matter what the season, getting the sleep your body needs is the key to better days.