June 7, 2010 -- Chronic insomnia may be associated with premature death, even independently of other chronic medical conditions such as heart disease or diabetes, according to a new study presented today at an annual conference on sleep.
Researchers led by Laurel Finn, a biostatistician at the University of Wisconsin in Madison, analyzed data on people enrolled in the Wisconsin Sleep Cohort Study who completed two to three mailed questionnaires in 1989, 1994, and 2000. Anyone who reported insomnia symptoms in at least two of the questionnaires was considered to have had insomnia. The researchers looked at four types of insomnia: difficulty falling asleep, difficulty getting back to sleep, waking repeatedly, and waking too early.
In June 2009, Finn and her team conducted a Social Security death index search and found that there were 74 deaths among 1,872 participants. They presented their findings at the 24th annual meeting of the Associated Professional Sleep Societies LLC in San Antonio. They found that:
- Overall mortality was three times higher among people with chronic insomnia than among people who did not have insomnia.
- Even when looking at the four different types of insomnia, the risk of premature death still held. In fact, the risk of premature death was two to three times higher among people who struggled to fall asleep, struggled get back to sleep, woke repeatedly, and woke too early.
The association between early death and chronic insomnia was independent of other self-reported chronic conditions that were taken into account, including emphysema, chronic bronchitis, heart attack, stroke, high blood pressure, heart disease, diabetes, and depression.
"The most surprising result was the increased high risk for mortality among individuals with chronic insomnia versus those without insomnia, even after adjustment for all of the potential confounding variables," Finn says. "The other important finding was the non-differentiation between subtypes of insomnia with respect to mortality risk."
Adults typically require between seven to nine hours of restorative sleep every night. According to a 2009 survey from the CDC, about one in 10 Americans reported difficulty sleeping; only 30% said they got enough sleep.The survey also showed that an estimated 50 million to 70 million Americans have chronic sleep disorders, such as insomnia.
The study was supported by the National Heart, Lung, and Blood Institute; the National Institute on Aging; and the National Center for Research Resources.The results suggest a need for doctors to more effectively treat insomnia even if the patient does not have other chronic medical conditions.
"Insomnia is a burdensome symptom and has a negative impact on sleep quality that may lead people to seek treatment," Finn says. "The identification of insomnia as a mortality risk factor may have clinical implications and raise the priority level for insomnia treatment."