Daylight Saving Time Starts Sunday. Here's What Losing An Hour of Sleep Really Does to Your Body

From TIME - March 9, 2018

The start of Daylight Saving Time, when the clocks spring forward by an hour, is among the most hated days of the year. Aside from the obvious reasonlosing an hour of sleepresearch has shown that the time change, which this year falls on March 11, may contribute to everything from lost productivity to a heightened risk of heart attack and stroke.

How can resetting your clocks do all that? TIME asked Dr. Cathy Goldstein, an assistant professor of neurology at the University of Michigan School of Medicine Sleep Disorders Center, what really happens to your body when you lose an hour of sleep for Daylight Saving Time.

Your circadian rhythm is thrown off

Daylight Saving Times true impact goes beyond losing an hour of sleep, Goldstein says. Your circadian rhythm, an internal clock that exists so that wakefulness is promoted during the day, and sleep is promoted at night, Goldstein says, is also affected.

Thanks to circadian rhythms, the body begins secreting melatonin, a sleep-promoting hormone, around 9 p.m., with levels dropping way off by the next morning. Light exposure can moderate your circadian rhythm a bit, but the body more or less relies on consistent sleep and wakefulness cuesso when theyre altered, even by an hour, your sleep gets misaligned.

You take somebody whos very sleepy when they get up at 6 a.m., and then they get up at 6 a.m. during Daylight Saving Time, and for them thats physiologically 5 a.m., Goldstein says. Thats a big problem, because youre waking up at a time when the circadian system is not yet promoting alertness. Its still pushing for that sleepiness.

Plus, you may lose sleep on both ends of your cycle, since your normal bedtime will feel earlier, potentially making it harder to fall asleep in the first place. Even worse, DST happens on a weekend, when many people stay up later and sleep in. Because of the cumulative effects, you lose more like two or three hours of sleep, and it could take up to a week to get back on a normal schedule, Goldstein says.

Lost sleep directly affects your health

Heres how to minimize the impact


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