Study found artificial light might be disrupting circadian rhythms
THURSDAY, Aug. 1, 2013 (HealthDay News) -- Putting down your phone and living for a week with nothing but sunlight and campfires may bring your body clock in sync with nature's rhythms, a small study suggests.
And, researchers found, even avowed night owls turn into early birds after a week of camping in the woods with no sources of artificial light -- including smartphones, computers and TVs.
"We've already known that artificial light is keeping us up at night," said lead researcher Kenneth Wright, of the University of Colorado at Boulder. But this study, he said, was an attempt to "quantify" the effect that light exposure, both artificial and natural, may be having on the human body's internal "clocks."
"What we found suggests that it's not just artificial light that's keeping us awake," Wright said. "It's also a lack of daylight."
For the study, reported in the Aug. 1 online issue of Current Biology, Wright's team recruited eight healthy adults who stuck with their normal daily routines for one week, and then spent another week camping together. During the trip, the only lights allowed were sunlight and campfire light.
At the end of each week, the researchers took saliva samples to measure study participants' melatonin -- a hormone that becomes more active in the evening, to help people fall asleep, then drops off in the early morning so they can wake up bright-eyed.
Typically, Wright's team found that when people were at home they went to bed after midnight, on average, and rose at around 8 a.m. On the camping trip, however, they turned in earlier and rose earlier.
More importantly, the campers' "biological night" kicked in about two hours earlier, Wright said. That is, their melatonin levels began to rise around sunset, and then drop off around sunrise, almost an hour before they woke up.
"So they became much more in sync with the natural world," Wright said.
And what's the big deal about that? It's not clear yet, according to Wright. "Does it make a difference in how they feel?" he said. "That's an important question."
What does seem clear, Wright added, is that "the type of light we're exposed to really does have a big impact on our biology."
And it's possible, he noted, that exposure to artificial light at night -- and a lack of sun during the day -- are contributing to some people's sleep problems and morning grogginess.
Past studies have found that in the typical artificially lit lifestyle, people's melatonin levels do not drop off until about two hours after they wake up. In essence, Wright said, their biological night is still in effect even though they are awake.
The new findings are "not surprising," said Dr. Jordan Josephson, an ear, nose and throat, and sleep specialist at Lenox Hill Hospital in New York City. He noted that it's known, for example, that people who do shift work -- and are exposed to artificial light when the outside world is dark -- often suffer from fatigue.
Another sleep specialist agreed that the findings are not surprising, but added that they are potentially important.
For one, they may offer an explanation for why melatonin levels typically don't hit their low until two hours after people wake up, said James Wyatt, an associate professor of behavioral sciences at Rush University Medical Center in Chicago.
It would "make much more sense" for the melatonin pattern to look like that of the campers in this study, Wyatt said.
There are still plenty of questions, he cautioned. "This is a tantalizing study, but it's preliminary." The experiment, Wyatt said, needs to be repeated in larger groups of people, and in different settings.
Still, Wyatt said, the biological effect was "very consistent" for all eight campers in this study -- which suggests that a similar effect would be seen in a larger group.
For now, Wright suggested that if you're someone who typically stays up late and regrets it in the morning, it wouldn't hurt to dim the artificial lights and get more sunshine.
"Reduce your exposure to light from the TV and computer at night," he said. "And during the day, get out more. Eat your breakfast outside, or go for a walk in the afternoon."
Wyatt agreed that at the very least, there's unlikely to be a downside to doing those things.
The U.S. National Institute of General Medical Sciences has more on circadian rhythms and health (http://publications.nigms.nih.gov/insidelifescience/biological-clocks.html ).
SOURCES: Kenneth Wright Jr. Ph.D., associate professor, integrative physiology, University of Colorado at Boulder; James Wyatt, Ph.D., associate professor, behavioral sciences, Rush University Medical Center, Chicago; Jordan Josephson, M.D., Lenox Hill Hospital, New York City; Aug. 1, 2013, Current Biology, online