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Published September 1, 2010
Suffering from insomnia? A new finding could make you lose even more sleep.
Men with chronic insomnia who also sleep less than six hours a night have a higher risk of early death than "normal" male sleepers who get more than six hours of shut-eye, a new study suggests. (Take National Geographic magazine's sleep quiz.)
Insomnia—difficulty falling or staying asleep—is the most common sleep disorder, affecting about 30 percent of people in the U.S., according to the American Academy of Sleep Medicine. Chronic insomniacs are those who have had the disorder consistently for at least a year.
After decades of mixed findings, the new report shows that insomnia is a "serious disease with significant physical consequences, including mortality," said study leader Alexandros N. Vgontzas, director of Penn State University's Sleep Research & Treatment Center in Hershey, Pennsylvania.
Though the researchers didn't specifically study people who reported lack of sleep due to their lifestyle, Vgontzas emphasized that "losing sleep for whatever reason is bad for your health." For instance, he has published previous results showing that curtailing sleep in young adults by two hours a night for just one week is linked to inflammation that may cause cardiovascular problems.
The new study changes "how we view insomnia," said Vipin Garg, director of the Sleep Disorders Center at Trinitas Regional Medical Center in Elizabeth, New Jersey.
"It definitely is pointing attention to insomnia as more than a psychological disorder," said Garg, who was not involved in the research.
Insomnia Tracked Over Time
Study leader Vgontzas and colleagues randomly selected 741 Pennsylvania men between 20 and 100, with an average age of 50, to participate in the initial phase of the study, between 1990 and 1995.
First, the volunteers identified themselves as either insomniacs or non-insomniacs. Then they spent a night in a sleep lab, where scientists confirmed how long the subjects slept.
By combining the subjects' self reports and the lab data, the team determined that 6 percent of the men had chronic insomnia.
Between 1994 and 1997, the sleep researchers studied a thousand women with a similar age range to the men. The team found that 9 percent of the women had chronic insomnia.
By the time the scientists checked in on the subjects in 2007—14 years later for the men, 10 for the women—51.1 percent of the male chronic insomniacs who slept fewer than six hours a night had died, versus 9.1 percent of the normal male sleepers.
The findings suggest that chronic male insomniacs are four times more likely to die early—even after taking into account risk factors such as smoking, obesity, and sleep apnea, Vgontzas said.
There was no such link between insomnia and premature death in women—insomniacs and healthy sleepers both had a mortality rate of just over 2 percent during the study period.
There could be two reasons for the gender discrepancy, Vgontzas said: Since the women's study was started later, there was not as much time for follow-up as for the men. It's also possible there's a "gender effect"—though insomnia is less common in men, it's generally more severe, he said.
Flaws in Insomnia Study?
There were a few weaknesses in the insomnia study's design, said Garg, of the Sleep Disorders Center.
For instance, the number of subjects in the study was small: "To give that kind of bold statement [about mortality], you want to see a bigger sample," he said.
It's also possible that during their one night in the sleep lab, some subjects experienced something called a "first-night effect." In other words, the unfamiliarity of the surroundings may have influenced their sleep patterns.
Insomnia Not a Direct Killer
The researchers did not include cause of death in their study, but study leader Vgontzas said that "no one dies directly from insomnia."
Instead, the chronic disease probably just wears on people gradually, making them more likely to succumb to other ailments.
For instance, male insomniacs in the study who were also diabetic or had high blood pressure were even more likely to die during the test period than their relatively healthy counterparts.
There's also evidence that hyperarousal—a condition that causes some people to stay awake for long periods of time—can stress the cardiovascular system, the sleep center's Garg noted.
(Related: "Secrets of Sleeping Soundly Uncovered.")
Insomniacs Born Not Made?
Causes of insomnia are still poorly understood—it may be that some people are just "born poor sleepers," Vgontzas said. But even more mysterious is how to treat the condition.
For instance, insomnia medications are mostly geared toward combating occasional sleeplessness, and psychological interventions such as cognitive behavioral therapy don't seem to work for severe insomniacs, he said.
That's why federal agencies and companies need to support the search for better treatments, and doctors need to take insomnia diagnosis more seriously, Vgontzas said.
Doctors "are used to thinking insomnia is a nuisance," he said. "They have to change their attitude about that."
The insomnia-risk study appears September 1 in the journal SLEEP.
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