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Researchers Pinpoint Genetic Mutation in Chronic Night Owls


It can be incredibly frustrating to be perennially awake when the world is asleep. For some chronically sleep-troubled folks, the problem may lie in their genes, specifically the CRY1 gene. Sam Diephuls/Mario Cea Sanchez/Getty
It can be incredibly frustrating to be perennially awake when the world is asleep. For some chronically sleep-troubled folks, the problem may lie in their genes, specifically the CRY1 gene. Sam Diephuls/Mario Cea Sanchez/Getty

In a 9-to-5, early-bird-gets-the-worm kind of world, being a night person can be a drag.

Alina Patke knows. She has spent many late nights and early mornings peering into a microscope, poring over databases, trying to determine why her sleep patterns, and those of millions like her, are so different than what is considered normal.

While the rest of the world sleeps, Patke has been trying to figure out why she can't.

Now, after years of locking up at night, Patke, a researcher in the Laboratory of Genetics at The Rockefeller University in New York, has found an answer. Or at least part of one.

In a paper published in March in the journal Cell, Patke and her associates announced the discovery of a genetic mutation in night owls that helps explain why they are what they are. The variation is in the gene CRY1, which controls our circadian rhythms, the internal clock that determines when we sleep and when we wake.

In people with this genetic variation, the onset of sleep is delayed some two to two-and-a-half hours later than those without the variation. In effect, people with the mutation have a daily cycle longer than the normal 24 hours. And that throws them completely off rhythm from much of the rest of the world, which still expects them to get to work or school at the same time as everyone else.

"It's as if these people have perpetual jet lag, moving eastward every day," Michael W. Young, the head of labs at Rockefeller, tells Science Daily. "In the morning, they're not ready for the next day to arrive."

These people are not simple sleepyheads or preternaturally lazy. They're not somehow at fault for their one-step-behind lives.

It's in their genes. They are, almost literally, wired differently than the rest of the world.

"When we found it, we were pretty sure that's what it would be. It would have been an odd coincidence if it weren't that," Patke, the lead author of the paper, tells HowStuffWorks. "But showing that, rather than just thinking, 'That's what it must be,' ... it's been a lot of work.

"It's especially satisfying. I've always enjoyed being a scientist and working on this particular topic because it is so personal to me."

In Search of a Genetic Mutation

Patke and many others have been at this for about seven years. Earlier studies of a 46-year-old woman with DSPD — delayed sleep phase disorder, which affects up to 10 percent of the population — pointed to a problem with her internal clock, rather than something external.

After extensive gene mapping on the woman, scientists zeroed in on a variation in CRY1 as a possible culprit. Researchers took DNA samples from some of the woman's family members and found five who had the same variation. All had signs of DSPD or other sleep problems.

Patke, Young and other researchers then dove into genetic databases from around the world looking for CRY1 variations. They found dozens of people in Turkey with the dominant mutation, and discovered 38 of them with sleep disorders. The scientists looked at those subjects' families and found that none of the people without the mutation had sleep problems.

After scouring more databases, building models and crunching more numbers, the authors concluded that a mutation in CRY1 was indeed responsible for altering the circadian clock and bringing on DSPD in their subjects. They estimate that 1 out of every 75 people of non-Finnish European descent has the mutation. Studies on other populations are ongoing.

The scientists report that there's not a 100 percent correlation between the mutation and sleep disorders; not everybody who has the mutation has DSPD, and many with DSPD do not have the mutation. Patke has been tested. She, ironically, does not have the mutation.

Still, it's now clear that this variation in this single gene — a gene responsible for keeping us in a daily rhythm — has a strong correlation to DSPD and possibly other sleep disorders.

That, in decidedly unscientific terms, is a big deal.

"It's probably not a matter of life and death," Patke says, "but there are definitely correlations on how well you sleep and other comorbidities."

Lack of Sleep Is No Joke

According to the National Institutes of Health, sleep disorders can lead to a host of health problems, including an increased risk of hypertension, diabetes, obesity, depression, heart attack and stroke.

Patke's sleep problems, like millions of others, are still largely unexplained. The root causes could be physiological. They could be psychological. They could be a combination.

For those who stay up too late, get up too late and seem out of sync with the rest of the world, though, the discovery of a genetic mutation that might explain their plight — even if tests are not available to the public — should come as a relief.

"I think anybody who has this kind of problem, they would be interested in knowing: It's not their fault; it's just how they're made, right?" Patke says. "I think that can make a difference, psychologically."

That might not be as satisfying as a good night's sleep. But it's a start.

The researchers can be contacted regarding opportunities for participation in follow-up sleep studies at patkea@rockefeller.edu and young@rockefeller.edu.



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