In a world organized around the 9-to-5 grind, night owls get a bum rap. For staying up late they're pegged as undisciplined; for sleeping in they're dismissed as lazy. But according to new research, an out-of-sync sleep cycle may not be their fault: It's in their genes.
A study just published in Cell found that people who stay up late and have trouble getting up in the morning have a genetic mutation that slows their circadian clock, which regulates patterns of sleeping and waking. People with mutations in the gene, called CRY1, showed delays in falling asleep—they were awake two to two and a half hours later than those without the variant. That put them out of sync with the rest of the world. "Carriers of the mutation have longer days than the planet gives them, so they are essentially playing catch-up for their entire lives," Alina Patke, first author in the study, said in a statement.
A broken sleep cycle can mean struggling to sleep at night, trouble waking, and even settling for a series of long naps instead of a full night's sleep. The problem is typically diagnosed as delayed sleep phase disorder (DSPD), and is associated with serious health effects, including anxiety, depression, cardiovascular disease, and diabetes. Studies show DSPD affects up to 10 percent of the public.
Not all cases of DSPD can be attributed to the variant CRY1, but this is the first time a gene mutation has been implicated in the disorder. And it may be a fairly common variant. It's a small error; only one letter in the genetic instructions is wrong. Searching a gene database, researchers found it in 1 in 75 individuals of non-Finnish European ancestry.
That doesn't mean, though, that unlucky night owls are slaves to their genes, doomed to feel perpetually jet lagged. The circadian clock responds to external cues, meaning it can be managed with a carefully maintained sleep regimen and exposure to bright light during the day. Night owls can function in society and lead healthy, productive lives—but have a little pity: They've probably got to work just a little bit harder to do it.
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