for National Geographic News
Those who struggle to get out of bed in the morning may be able to hold their genes responsible, new research suggests.
Scientists have discovered that a person's waking habits are mirrored by body cells that are equipped with their own daily alarm clocks.
The work represents the first internal look at the biological clocks of those suffering from sleeping disorders, said study leader Steven A. Brown of the Institute for Pharmacology and Toxicology at the University of Zurich, Switzerland.
"One of the big surprises was that so much of our daily behavior was genetically encoded," Brown said.
"The idea that skin cells are telling us anything about our behavior was, for me, quite fascinating," he added.
The study investigated the circadian rhythm—the brain-controlled phenomenon that governs various body functions over a 24-hour period—of extreme late and early risers.
Larks and Night Owls
Suitable volunteers were recruited by the study team using TV advertisements shown between 3 a.m. and 4 a.m.
"We got both our early types and our late types that way," Brown said. "Some had not yet gone to bed, while others were already up."
Skin cells taken from the volunteers were cultured in the lab and injected with a bioluminescence gene found in fireflies.
These altered cells lit up or dimmed according to an individuals sleeping patterns, according to the study, which appears in today's online edition of the journal Proceedings of the National Academy of Sciences.
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