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Camping resets internal clock

After a week in the wild, people went to bed and got up earlier

CAMPING RESETS CLOCK  After a week spent camping (and away from all electric lights) in Colorado, volunteers fell asleep earlier and woke up earlier. Their internal clocks shifted, syncing up with sun, researchers found.

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A short camping trip could help people rise and shine.

After a week living in tents in Colorado’s Rockies, volunteers’ internal clocks shifted about two hours earlier, transforming night owls into early birds, researchers report August 1 in Current Biology.

“It’s a clever study, and it makes a dramatic point,” says Katherine Sharkey, a sleep researcher and physician at Brown University. People get much more light outside than they do indoors, and that can reset their internal clocks, she says.

A master clock in the brain controls the release of melatonin, a hormone that prepares the body for sleep. Melatonin levels rise in the early evening and then taper off in the morning before a person wakes up.

But because so many people spend their days indoors and their nights bathed in the glow of electric lights, the body’s clock can get out of sync. Melatonin levels ramp up later in the evening and ebb later in the morning — often after a person has woken up. The lingering sleep hormone can make people groggy.

Kenneth Wright Jr., a sleep researcher at the University of Colorado Boulder, and colleagues whisked eight volunteers away from artificial lights for a summer camping trip. After nightfall, the campers used only campfires for illumination — no flashlights (or cellphones) allowed.

While camping, the volunteers soaked up four times as much light as they got indoors. And they went to sleep and naturally woke up more than an hour earlier than they had before the trip. After the trip, the volunteers’ melatonin levels climbed around sunset and petered out at sunrise — two hours earlier than they had before camping.

People might not even need to rough it to nudge their internal clocks back. Because the light of a midsummer day is about 500 times brighter than typical office lighting, even brief stints outside could help.

“Start your day off with a morning walk, and open the shades to expose yourself to sunlight,” Wright advises.

Editor's Note: This story was updated on September 13, 2013 to make the comparison between summer sunlight and office lights more precise.

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