Sleep disorders tied to mortality risk

Poor quality sleep - whether from insomnia, sleep fragmentation, or nightmares - is associated with increased risk of death, according to several presentations this week in Seattle at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies.

One study, conducted at Penn State College of Medicine in Hershey, Pennsylvania, suggests that insomnia may be as hazardous as obstructive sleep apnea.

"Insomnia with objective short sleep duration is associated with an activation of the stress system, i.e., higher secretion of cortisol and increased risk of high blood pressure," said lead author Dr. Alexandros Vgontzas. He and his associates examined the effects of insomnia that persisted for at least 1 year and objective short sleep duration on mortality.

The subjects included 1741 randomly selected men and women. During 14 years of follow-up among men, the mortality rate was 19.6 percent. Among women, who were followed for 10 years, the mortality was 10.3 percent.

Compared with men who had normal sleep patterns and sleep durations of at least 6 hours, men with insomnia and a shorter duration of sleep had mortality risks that were up to 5-times greater. While mortality risk was also increased among women with similar characteristics, the association was not statistically significant.

"The longer follow-up of men may explain why we did not have the same finding in women," Vgontzas. "Another possibility is that men are more vulnerable physically to this type of insomnia, i.e., insomnia associated with objective short sleep duration."

Because "insomnia with objective sleep duration (of less than 6 hours) has significant medical consequences similar to sleep apnea, this type of insomnia should become a medical priority in terms of its detection and treatment," he said. "At this point there are no studies that have assessed which type of treatment - medication vs. psychotherapy vs. a combination of the two - is more effective," he added.

Another study assessed sleep duration using actigraphy, a small instrument worn on the wrist that measures body movement and detects patterns based on activity used to evaluate sleep-wake cycles. The investigators found that sleeping less than 5 hours per night increased the risk of death among elderly women, but not among elderly men.

Dr. K. L. Stone at California Pacific Medical Center in San Francisco and co-investigators monitored 3052 women (average age of 83.6 years) and 3055 men (average age 76.4 years) for at least three 24-hour periods.

Compared with women who slept at least 8 hours nightly, women who slept fewer than 5 hours had a significantly higher risk of death over 4.2 years of follow-up. Men who got fewer than 5 hours of sleep per night also had an increased mortality risk, but this was not statistically significant, which, again may be related to study conditions.