Before heading to bed on Saturday, November 2, many Americans will set their clocks back one hour to prepare for the end of daylight saving time (DST). In the states that change clocks (Arizona and Hawaii are the only ones that do not), this “fall back” time is always the first Sunday in November. This year, DST officially ends at 2 am on Sunday, November 3, 2024, after an eight month run that began March 10.
If you find yourself rejoicing each year over the extra hour of sleep, we hear you. But some medical experts say the extra slumber may have some unintended consequences for our health.
Here’s what you should know about the science behind why this time change may not be so great for health, and some tips for easing the transition.
Changing the Clocks on the Walls Can Throw Off Our Body Clocks
Setting the clock back affects your body’s circadian rhythms — “the physical, mental, and behavioral changes in your body that follow a 24-hour cycle,” according to the National Institute of General Medical Sciences (NIGMS) definition.
Our bodies expect certain things to happen at certain times during the day (like sleeping, waking up, and eating) based on cues from the sun and on your doing those things over and over again at the same time every day. For example, says Aneesa Das, MD, a sleep medicine, internal medicine, and pulmonary disease specialist at The Ohio State University Wexner Medical Center in Columbus. “Natural sunlight during the day and the absence of light in the evening help to drive our circadian sleep phase.”
When you shift that routine — even by an hour — your circadian rhythms get slightly thrown off, similar to the effect of jet lag. The result: Your circadian rhythms become slightly misaligned from the time on the clock, which can throw off the timing of several daily processes that happen in the body, like sleep, digestion, and cardiovascular functioning.
And while many people may not feel all that affected by the change, large-scale data suggests that the risk of health problems like heart attacks and accidents may increase because of the change to and from DST.
One study that followed healthcare workers for eight years revealed an 18 percent uptick in safety-related human errors in the week following DST in the spring and a 5 percent increase after the end of DST in the fall.
Any disruption in the sleep or circadian cycle has the potential to increase risk of disease, says Matthew Morgan, MD, a primary care physician at Ochsner Health Center in Chalmette, Louisiana. Changes in daylight patterns — like the shorter days during fall and winter months — also affect your body’s normal sleep-wake cycle.
But those changes happen gradually over the fall months as the days get shorter (particularly in places farther north). DST clock changes happen overnight. “It can take several weeks for your circadian rhythm to adjust to the change that the end of DST brings,” adds Whitney Hardy, MD, a family medicine physician at Ochsner Health Center in Gretna, Louisiana.
Misaligned Body Clocks Can Up Risk of Seasonal Depression
Another problem with shifting the clocks is that any sudden changes in sleep and daylight exposure can increase mood changes and risk of seasonal affective disorder (SAD), too, Dr. Morgan says.
SAD is a form of depression that follows a recurring seasonal pattern. And even for people who don’t have the more severe symptoms associated with depression (decreased interest in work, friends, or hobbies; insomnia; dramatic changes in appetite; feeling worthless or empty; suicidal thoughts; and others), estimates suggest that a Lots of people experience these mood changes to a lesser extent with symptoms like sad mood, low energy, trouble concentrating, weight gain, and increased cravings for carbs — more commonly referred to as the “winter blues.”
SAD typically strikes during the fall and winter months, when daylight hours are shorter, Morgan says. Danish researchers reported data that suggested depressive episodes increased by as much as 11 percent following the fall setting back of the clocks.
6 Tips for Making the Transition Easier on Your Body
The good news is that you can minimize the effects of shorter days after daylight saving time ends this fall. Try following these tips:
1. Start With Basic Sleep Hygiene
Practicing healthy sleep habits is important no matter what time of year it is, Morgan says. If you’re already sticking to a consistent sleep routine, you’re less likely to be affected by the hour switch than if you’re regularly shifting sleep and wake times from day to day.
Going to bed and waking up at the same time every day, using your bed only for sleep and sex, avoiding caffeine in the late afternoon and evening, and limiting bright light exposure in the evenings (turning off electronic devices at least 30 minutes before bed ) can all help establish a consistent sleep routine.
“Relaxing activities, such as reading in a different room or going for a walk, before bed can also be of benefit,” Morgan says.
The end of daylight saving time may offer a good opportunity to reevaluate your sleep habits and figure out how to improve them, says Jamie M. Zeitzer, PhD, a research professor of psychiatry and behavioral sciences (sleep medicine) at the Stanford Center for Sleep Sciences and Medicine in Palo Alto, California. “Kind of like a New Year’s resolution, (DST) is a good excuse to do something about your sleep.”
2. Don’t Procrastinate When It Comes to Changing the Clocks
To make the time change feel more natural, Dr. Hardy suggests setting all the clocks in your home back the night before the switch. This way, when you wake up, you’ll be prompted (by your clocks) to start adjusting to the new time right away (and a day ahead of the start of the workweek on Monday, when you might be more likely to be affected by being thrown off schedule).
As you adjust to the time change that first week, it may be tempting to take naps or sleep in on the weekends, but do your best to stick with your regular sleep schedule as best as you can. If you feel like you must take a nap, the Cleveland Clinic suggests taking one earlier in the day for 20 minutes max.
3. Get Natural Sunlight in the Morning for Better Sleep and Mood
Natural sunlight plays a key role in regulating mood and sleep-wake cycles. In particular, getting sunlight first thing in the morning helps tell your body it’s morning and it’s time to be awake, helping you realign your body’s circadian rhythms to the new non-DST time, according to Dr. Zeitzer.
One study found that office workers who received higher levels of sunlight in the morning during winter months reported better sleep quality, lower levels of depression, and reduced sleep-onset latency (the time it takes to fall asleep once your head hits the pillow) compared with office workers who received lower levels of sunlight.
Other research came to a similar conclusion. After studying data from 400,000 participants, UK researchers found that each additional hour people reported spending outdoors during the day was tied to lower odds of depression, antidepressant usage, and low mood. More time spent in daytime light was also linked to greater ease with getting up in the morning and less frequent tiredness throughout the day.
Exposure to light through your windows helps, too, Zeitzer says. Think about repositioning a desk (if you can) or the table where you eat breakfast.
4. Consider Light Therapy as a Stand-In for Natural Sunlight
If you typically wake up before sunrise, or you have a hard time getting outdoors, consider using light therapy as a stand-in for natural sunlight, Zeitzer says. It involves the use of a light therapy box, a small device that emits a type of artificial light shown to mimic outdoor light.
When used in the morning, light therapy can signal to your body that it’s time to be awake, helping kick-start your internal clock so it aligns with the clock on your phone. And remember, realigning your internal clock is especially important right after the end of DST.
For maximum effectiveness, use the light box for about 20 to 30 minutes within an hour of waking up every day, making sure to sit about 16 to 24 inches away from the box.
5. Use Exercise to Boost Mood and Energy
Exercise releases natural feel-good chemicals in your brain that can boost your sense of well-being and helps distract you from negative thoughts that may dampen your mood. It’s why exercise helps boost energy levels, which helps you cope with some of that extra fatigue you might be feeling, given the shortage of sunlight and new time, Hardy says.
In addition to light therapy, aerobic exercise may also help lessen mood changes (and depression symptoms) tied to the change of seasons and the slight misalignment of our body clocks. Exercise is associated with an uptick in neurotransmitters and proteins called neurotrophic factors, which are thought to lessen symptoms in people with depression.
Just note that exercising too close to bedtime may interfere with sleep (by blocking the release of melatonin, the hormone that signals to your brain it’s time to sleep). For this reason, it’s best to avoid any heavy workouts within a few hours before your regularly scheduled bedtime.
6. Support Better Sleep With Good Dietary Choices
What you eat during the day (and especially in the hours before bed) can certainly affect your sleep. If you’re trying to optimize sleep through DST transitions, think about dietary choices that support good sleep. Avoid alcohol and caffeine at bedtime, as well as spicy and fatty foods. You might also want to avoid high-protein meals at dinnertime — protein takes longer for your body to digest, which can ultimately interfere with your sleep.
And throughout the whole day, focus on eating a nutrient-dense, balanced diet. Research suggests a link between better sleep quality and antioxidant-rich foods, such as fruits, as well as a diet that is low in sugar and simple carbohydrates, and also adequate in protein. Eating too close to bedtime may also interfere with sleep.
The Takeaway
- The end of daylight saving time can disrupt the body’s natural circadian rhythms, increasing the risks of accidents and even heart attacks.
- To ease the transition to shorter daylight hours, stick to a consistent sleep schedule and set your clocks back the night before the switch.
- Getting regular exposure to morning sunlight (or using a light therapy box), as well as maintaining a good diet and regular exercise, can also support good sleep.
With additional reporting by Kristen Cherney.
