Every fall, we prepare to reset our clocks and gain a precious hour of time. The trees lose the last of their leaves and your winter coat emerges from the depths of your closet. Well, not for the lucky ones evading cold weather somewhere south.
Your body might have some difficulty adjusting to the time change. But luckily, this switch is easier than the spring time change, according to Charles Czeisler, MD, PhD, a Mass General Brigham sleep medicine specialist. Dr. Czeisler is chief of the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital. “We’re about to go in the time zone that we should really stay on year-round,” he says.
Daylight saving time refers to the period between March and November when the time zone changes off standard time. We set the clocks forward one hour on the second Sunday of March, and fall back to standard time on the first Sunday of November.
The practice started when Congress passed the Uniform Time Act of 1966 to “save daylight.” The change allows for more hours of light in the evening during warmer months.
Circadian rhythms are daily cycles for many different functions in your body. A structure called the suprachiasmatic nucleus — Dr. Czeisler calls it the “central circadian pacemaker” — controls the timing of all these cycles. This structure in your brain sets all your internal clocks to a period about 24 hours long.
Dr. Czeisler explains that your environment, especially the light-dark cycle, can influence the exact timing of your central circadian rhythm. “When you have a mismatch between the local time and your circadian rhythm, it leads to greater sleepiness during the daytime and difficulty sleeping at night,” he says. He offers several tips to get better sleep and maximize your health when daylight saving time ends.
Dr. Czeisler recommends starting to shift your sleep schedule gradually. On the few nights leading up to the time change, try going to bed and waking up a little later.
Caffeine works as a stimulant to keep you awake and alert, but it can stay in your system for more than 10 hours. “Using caffeine after 2 p.m. or 3 p.m. will interfere with your sleep at night,” says Dr. Czeisler.
In the hours leading to bedtime, your body naturally releases a hormone called melatonin to help you fall asleep. When you set the clocks back, your melatonin will rise closer to dinnertime until your circadian rhythm adjusts.
“Eating at a time when melatonin rises can cause insulin resistance and higher glucose levels, putting you at increased risk for diseases like diabetes,” explains Dr. Czeisler. “You might want to eat an hour earlier than you usually would for a few days.”
“We ordinarily tell people to avoid exposure to light in the evening, especially light from blue-enriched screens,” says Dr. Czeisler. “But in this case, blue-enriched white light can help to shift your circadian rhythm one hour later so that you won’t experience early morning awakening.”
You probably think of your phone and computer screens emitting blue-enriched white light. But this wavelength also comes from your tablets, many new television screens, and especially all the new LED lights in our environment.
You might find yourself waking up too early after the time change. Maybe you regularly experience early morning awakening, or maybe you just like waking up with the sun.
But if you still go to sleep at the same clock time, you may lose an hour of sleep if you wake up at an earlier clock hour after the transition. To make sure the earlier clock time of sunrise doesn’t deprive you of that extra hour, try using a sleep mask to block out the light.
Some of these tips — including adjusting your sleep schedule early and increased exposure to light — come with a caveat. They only apply if you normally get enough sleep each night.
More than 1 in 3 American adults doesn't get enough sleep, according to the Centers for Disease Control and Prevention (CDC). The average adult needs at least 7 hours of sleep, which means spending 7.5-8.5 hours in bed, and some need up to 9 hours of sleep.
“A lot of people will go to bed so much later on the Saturday night of the time change that they don’t benefit from the chance to get an extra hour of sleep. But the biggest thing you can do is go to sleep at your usual bedtime and take advantage of the extra hour of sleep,” highlights Dr. Czeisler. “If you’re chronically sleep-deprived, this will be an opportunity to make a habit of going to sleep a little bit earlier.”
You can’t make up for chronic sleep deficiency in one night, but you can kick-start a change to your routine. You’ll end up getting an additional hour of sleep every night if you continue going to sleep an hour earlier than you used to.
The end of daylight saving time is a more natural transition for our circadian rhythms than springing forward. The change causes less of a disruption to our body’s functions, including fewer time change sleep problems. Dr. Czeisler notes that we see a lower risk of heart attacks and vehicle crashes in the week following the reset.
While you may need a few days to adjust to the time change, falling back has its benefits. “Ordinarily, our biology makes it tough to go to bed earlier than our habitual bedtime. This is a special time when you have a leg up to consistently add an hour to your sleep,” he says, “so prepare to get more sleep, and don’t waste this opportunity.”