Daylight saving time will be coming to a close this weekend. The onset of daylight saving time in the spring is linked to more negative health consequences like a higher risk of obesity, metabolic syndrome, cardiovascular disease and depression. However, the clocks “falling back” in November are also associated with some adverse health outcomes such as disrupted sleep, more strokes and the incidence of car accidents going up. With daylight saving time happening Sunday, Nov. 3, here’s your guide to what to know including when DST is happening, a brief history, who doesn’t participate, how changing clocks impacts health and how to prepare.
When does daylight saving time start and end?
Daylight saving time ends at 2 a.m. local time on Sunday, Nov. 3, when we “fall back” and gain an extra hour of sleep. We’ll get an extra hour of daylight in the mornings but lose an hour of daylight in the evenings.
Daylight saving time will begin again next year on Sunday, March 9, 2025, when we “spring forward” and lose an hour of sleep. We’ll gain an extra hour of light in the evenings but have darker mornings.
A brief history of daylight saving time
Daylight saving time was introduced in the United States in 1918 as a way to conserve energy during World War I. However, studies have shown that it isn’t actually saving much energy.
Some have credited Founding Father Benjamin Franklin with originating the idea of a seasonal time change after he proposed regulating time in a satirical essay, but Philadelphia’s Franklin Institute has disputed this. Contrary to popular belief, farmers didn’t advocate for daylight saving time, either; in fact, agricultural groups called for a repeal of daylight saving time in 1919, saying that the biannual changes were disruptive to their workday. After the 1919 repeal, daylight saving time was still observed but at inconsistent times that varied across different regions.
The Uniform Time Act of 1966 got most of the country on the same page by mandating national start and end dates to daylight saving time, though states were still allowed to opt out.
Who doesn’t participate in daylight saving time?
These U.S. states and territories have chosen not to switch their clocks twice a year:
How the end of daylight saving time affects your health
The shift back to standard time in November can feel easier than adjusting to daylight saving time in March. After all, we’re gaining an extra hour of sleep, right? But experts say there are still negative consequences for our health.
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Sleep patterns are disrupted. Shelby Harris, a psychologist and director of sleep health at Sleepopolis, told Yahoo Life that an extra hour of sleep can still cause sleep problems. “When we gain an hour of sleep in the fall, it can cause early morning awakenings and difficulties falling asleep at night,” she explains.
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Stroke risk goes up. A 2016 Finnish study found that moving the clock back or ahead one hour temporarily increases the risk of ischemic stroke — the most common type of stroke caused by a clot blocking blood flow to the brain — likely thanks to the disruption in circadian rhythm (aka our body’s internal clock).
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Depression increases. A 2016 Danish study found that depression diagnoses increase “immediately after” standard time begins in the fall. Some of that may have to do with the onset of seasonal affective disorder (SAD), which affects about 5% of the U.S. population and is triggered by shorter, darker, colder days.
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Car accidents increase. A spokeswoman for AAA’s Auto Club Group told the Associated Press that earlier sunsets in the afternoon mean darker driving conditions in the evening and higher instances of accidents on the road.
How to prepare for the time change
Here are some experts’ tips on making the fall time change more bearable.
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Gradually adjust your sleep and wake times. Natalie D. Dautovich, an assistant professor at Virginia Commonwealth University and an environmental scholar at the National Sleep Foundation, told Yahoo Life that she suggests gradually pushing back the times you go to bed and wake up by 15 minutes in the days leading up to daylight saving time ending — so that it isn’t as much of a shock to your system when the clocks change by one hour.
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Establish a good bedtime routine. Having an established bedtime routine can help signal to your body that it’s time to wind down and make it easier to adjust to time changes. Judy Ho, a licensed clinical and forensic neuropsychologist, told Yahoo Life you should have a calming evening routine that involves putting away all electronic devices, especially blue-light devices. Harris also suggests avoiding any hard exercise, heavy meals, caffeine or alcohol right before bed.
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Get plenty of sunlight during the day — and first thing in the morning. At night and before it’s time to wake up, keep your room dark with the curtains closed to help you stay asleep an hour longer. Then, when it’s time to get up, get plenty of sunlight. Jamie Zeitzer, a Stanford University professor of psychiatry and behavioral sciences, told Yahoo Life to expose yourself to bright light as soon as possible. “Going out early in the morning, getting that good dose of light — that’ll help you shift faster into the new time,” Zeitzer says. Getting a healthy helping of sunlight each day could stave off depression as well — reducing your risk by up to 20%, according to one study. If natural sunlight isn’t an option, try light therapy or a sun lamp, which can improve mood and sleep quality at night.
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Stick to your new sleep and wake times. Once the clocks have changed, be consistent and stick to your new wake-up and bedtime routines, and try to avoid taking naps during the day.
