Stillwater News Press

Our World

August 14, 2013

Waking up tired? Blame electricity

(Continued)

Wright and his colleagues outfitted eight subjects with activity-tracking watches that carry light intensity detectors and motion sensors to keep tabs on sleep and wake times. For the first week, the participants went about their lives, spent mostly in artificially lit buildings. They then spent 24 hours in a lab, where the researchers periodically tested the melatonin levels in their saliva. In the second week, the group went camping in the Colorado Rockies, where they could sleep and wake up whenever they wanted but had no access to TV, cell phones or flashlights. Their world was illuminated only by sunlight and campfires. The group returned from their excursion for another stint of saliva sampling.

Data from the watches showed that subjects got about the same amount of sleep in the two settings. But the shift from artificial to natural light, which nearly quadrupled their total light exposure, also tinkered with their internal clocks. After camping, the subject's biological cycles had shifted to align with the sun. Their bodies released melatonin right at sunset - two hours earlier than under artificial light conditions - shut it off again just after sunrise, the team reported last week in Current Biology.

"When we expose ourselves to only natural light, we are in sync with that light-dark cycle quite strongly," Wright says.

The natural night owls in the group saw an especially dramatic shift in their melatonin cycle and became more similar to the early birds. The team suggests that artificial light had been exerting a particularly strong influence on the internal clocks of the night owls. The subjects weren't asked to report whether they felt less drowsy after the change in lighting.

Observing changes in human rhythms in a natural environment represents a "breakthrough," says Marie Dumont, a chronobiologist at the University of Montreal. "I think we forget most of the time that the knowledge that we have comes from laboratory and artificial conditions," she says. Dumont cautions, however, that few conclusions can be drawn from this small group of individuals. Changes in physical activity during the camping trip and the social interaction subjects had also likely influenced the retiming of their internal clocks, she says.

Text Only | Photo Reprints
Our World
Must Read
Buy & Share Photos
NewsPress e-Edition
NewsPress Specials
AP Video
Raw: Japanese Soldiers Storm Beach in Exercises Raw: Weapons Fire Hits UN School in Gaza Raw: Rocket Launches Into Space With Cargo Ship Broken Water Main Floods UCLA Two Women Narrowly Avoid Being Hit by Train In Virginia, the Rise of a New Space Coast New Sanctions on Key Sectors of Russian Economy Crayola Announces Family Attraction in Orlando US Ready to Slap New Sanctions on Russia Kerry: Not Worried About Israeli Criticism Boater Rescued From Edge of Kentucky Dam Girl Struck by Plane on Florida Beach Dies Rodents Rampant in Gardens Around Louvre House to Vote on Slimmed-down Bill for Border Looming Demand Could Undercut Flight Safety Raw: 2 Shells Hit Fuel Tank at Gaza Power Plant Raw: Massive Explosions From Airstrikes in Gaza Giant Ketchup Bottle Water Tower Up for Sale Easier Nuclear Construction Promises Fall Short Kerry: Humanitarian Cease-fire Efforts Continue
Stocks
NDN Video
Weird 'Wakudoki' Dance Launches Promotional Competition Two women barely avoid being hit by train Chris Pratt Adorably Surprises Kids at a 'Guardians of the Galaxy' Screening Chapter Two: Designing for Naomi Watts NOW TRENDING: Peyton Manning dancing at practice "The Bachelorette" Makes Her Decision Thieves pick the wrong gas station to rob Golden Sisters on '50 Shades' trailer: 'Look At That Chest!' Staten Island Man's Emotional Dunk Over NYPD Car - @TheBuzzeronFOX GMA: Dog passes out from excitment to see owner Baseball Hall of Famers Inducted 'Hunger Games: Mockingjay Part 1' Sneak Peek Florida Keys Webcam Captures Turtles Hatching Morgan Freeman Sucks Down Helium on 'Tonight Show' Robin Wright Can Dance! (WATCH) She's Back! See Paris Hilton's New Carl's Jr. Ad Big Weekend For Atlanta Braves In Cooperstown - @TheBuzzeronFox Chapter Two: Becoming a first-time director What's Got Jack Black Freaking Out at Comic-Con? Doctors Remove 232 Teeth From Teen's Mouth