Researchers found an elevated risk of death in men with a complaint of chronic insomnia and an objectively measured short sleep duration. The results suggest that public health policy should emphasize the diagnosis and appropriate treatment of chronic insomnia.
Compared to men without insomnia who slept for 6 hours or more, men with chronic insomnia who slept for less than 6 hours were four times more likely to die during the 14-year follow-up period (odds ratio = 4.33). Results were adjusted for potential confounders such as body mass index, smoking status, alcohol use, depression, and obstructive sleep apnea. Further adjustments for hypertension and diabetes had little effect on the elevated mortality risk (OR = 4.00). No significant mortality risk was found in women with insomnia and a short sleep duration of less than 6 hours (OR = 0.36).
"The primary finding of our study is that insomnia, the most common sleep disorder, is associated with significant mortality in men," said principal investigator Alexandros N. Vgontzas, MD, professor of psychiatry at Penn State College of Medicine and Hershey Medical Center in Hershey, Pa. "Until now, no study has demonstrated that insomnia is associated with mortality. Our different results are based on our novel approach to define insomnia on both a subjective complaint and the objective physiological marker of short sleep duration measured in the sleep lab."
The study involved 1,000 women with a mean age of 47 years and 741 men with an average age of 50 years. They provided a comprehensive sleep history, received a physical exam, and had their sleep evaluated during 1 night in a sleep laboratory. Sleep duration was measured objectively by polysomnography, and the presence of chronic insomnia was defined by a complaint of insomnia with a duration of at least 1 year; 8% of women and 4% of men had chronic insomnia with a sleep duration of less than 6 hours.
After about 10 years of follow-up for women and 14 years for men, 248 participants (14%) were deceased. The 14-year adjusted mortality rate for men was 9.1% for "good sleepers" and 51.1% for insomniacs who slept less than 6 hours.
The authors cautioned that 6 hours of sleep is not recommended as the optimum sleep duration for the general population. They used a 6-hour cut-off point only for the statistical evaluation of the severity of insomnia.
The study appears in the September 1 issue of the journal SLEEP.