Your Brain Does a Very Strange Thing When You Sleep in a New Place

There's a reason you sleep worse on vacation.

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First night of vacation! You’ve been traveling all day, your body is exhausted, and you feel like you could pass out the second your head sinks into that marshmallowy hotel pillow. You sleep through the night—then wake up the next morning feeling groggy, grumpy, and garbagey. (Those are just a few of the clear signs you’re not sleeping deeply enough.) What’s the deal? This was not in the brochure. 

A new sleep study from Brown University reveals that it isn’t just jet lag that disturbs our dozing on holiday; it turns out many of us sleep poorly on the first night of vacation—or the first night in any unfamiliar room—because our brains actually remain one-half awake through the night when we sleep in a new place.

Sleep scientists call this phenomenon First-Night-Effect (FNE). Researchers have known about it for a while, but only recently discovered what, exactly, is happening in our sleepy heads to cause it. The Brown team, led by researcher Masako Tamaki, used advanced neuroimaging techniques to track brain activity in several sleepers over a few nights. What they found not only confirmed that FNE is indeed a real thing, but that it’s caused by one hemisphere of the brain staying in an active state through the night while the other dozes peacefully. Simply put: one half of your brain plays night watchman for the other half.

In this vigilant state, your partly-awake hemisphere becomes extra sensitive to external stimuli—say, a thump in the hallway, a truck blundering down the road, or a bug buzzing past your ear—preventing your brain from reaching a fully restful sleep. Subjects in the Brown FNE study jolted awake to such “deviant” sounds throughout the first night, thanks to their asymmetrical brain activity. Fortunately, “None of these asymmetries were evident during subsequent sleep sessions,” a spokesman for the Brown study notes. In other words, your first night in a new place may always be rough—and here are the signs you’re headed for an awful night’s sleep—but your brain learns quickly to chill out.

Our nomadic ancestors would no doubt thank their FNE hemisphere for keeping them alert to skulking bears and bogeyman as they camped from plot to plot—but for us sleep-desperate modernists, it’s easy to be annoyed. Is there any way to turn off your brain’s FNE vigilance? Sleep scientists have some insider advice for you, but in the meantime you might try deafening your vigilant brain to external stimuli altogether. To calm your inner watchman, invest in a pair of earplugs, or make these changes to turn your bedroom into the ideal sleep environment.

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