Illustration: Kieran Blakey

The Nuance

This Is Why You Keep Waking Up In the Middle of the Night

The science behind that silent, malfunctioning alarm clock in your brain

Elemental
Published in
5 min readJan 9, 2020

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It’s three a.m., but you don’t need to check your phone to know that.

You know it’s that time because you always wake up at three a.m. It’s like your brain is equipped with a silent, malfunctioning alarm clock that rings you awake each night despite your earnest intention to sleep soundly for a full eight hours.

The funny thing is that everyone wakes up multiple times each night. But in most cases, these middle-of-the-night arousals are so brief and shallow that the brain doesn’t recall them in the morning.

“The average adult awakens seven to 15 times each night, and this is normal,” says Michael Perlis, director of the Behavioral Sleep Medicine Program at the University of Pennsylvania’s Perelman School of Medicine. He says these arousals tend to be “amnestic,” meaning a person doesn’t usually remember them. They last anywhere from a few seconds to a few minutes, and they usually coincide with transitions from one sleep stage to another. “Exactly why these happen is up for debate,” Perlis says. “But you tend to shift your body position when you have these brief awakenings, and that’s a good thing.” If your…

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Elemental

I’m a frequent contributor at TIME, the New York Times, and other media orgs. I write mostly about health and science. I like long walks and the Grateful Dead.