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Daylight Saving Time “fall back” doesn’t equal sleep gain

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The first Sunday of November marks the end of Daylight Saving Time, officially at 2:00 am. The notion of gaining an extra hour of sleep may seem appealing, but the reality is often different. The change in the body's daily sleep-wake cycle can cause disturbances that can disrupt sleep for days.

 Studies have examined whether losing or gaining an hour of sleep due to Daylight Saving Time affects health, with mixed results. Heart attack rates have been observed to increase on the first day of the spring transition to Daylight Saving Time, but other areas, such as driving accidents, workplace safety, and school performance, have had varied results.

Dr. Yvonne Harrison's review in Sleep Medicine Reviews notes that a one-hour shift in the sleep cycle can impact sleep for up to a week. The adjustment to the new schedule can be challenging for short-sleepers and early risers.

The daily cycles of physical, mental, and behavioral changes that we experience are known as circadian rhythms. These rhythms are kept on a 24-hour cycle by the daily cycle of light and dark. Sleep is a crucial component of these rhythms, and it can be affected by external factors such as Daylight Saving time or exposure to light.

It can be challenging to avoid the effects of Daylight Saving time on sleep. However, being aware that it can take up to a week for our circadian and sleep rhythms to adjust to the new clock can be helpful. Regular exercise at the same time each day, adhering to a consistent sleep schedule, and taking short afternoon naps during the week may help restore lost sleep and get our sleep cycle back on track.

In the fall, not everyone benefits from the extra hour of sleep promised by Daylight Saving Time. Many people have difficulty falling asleep, wake up earlier, and are more likely to wake up during the night in the following week. This adjustment is particularly challenging for individuals who are short-sleepers, logging less than 7.5 hours of sleep per night, and early risers.

Similarly, in the spring, the adjustment can be difficult for larks and short-sleepers. A one-hour shift in the sleep cycle can affect sleep for up to a week. While research has shown a small increase in heart attacks on the first day of the spring transition to Daylight Saving time, the broader picture of the effect of these transitions on the sleep cycle should not be overlooked.

Caroline Buckee

Caroline Flannigan is an epidemiologist. She is an Associate Professor of Epidemiology and is the Associate Director of the Center for Communicable Disease Dynamics.

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