Quality, in addition to quantity, is important for maintaining health, according to a research abstract that was presented on Wednesday, June 10, at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies.
Results indicate that over the average follow-up of eight years, 854 of the 5,614 participants died. Two sleep-stage transition types were associated with higher mortality risk: wake-to-non-REM and non-REM-to-wake.
According to lead author Alison Laffan, PhD, former graduate student at the Johns Hopkins Bloomberg School of Public Health and current post-doctoral fellow at the California Pacific Medical Center in San Francisco, Calif., mounting evidence from a number of studies shows that poor sleep increases risk for adverse health outcomes.
"In light of this growing body of evidence, people should strive to maintain good sleep habits, such as going to bed and getting up at the same time each day and sleeping for seven to eight hours each night," said Laffan.
The study involved data from 5,614 Sleep Heart Health Study participants who underwent overnight polysomnography to characterize sleep. Health outcomes were monitored for the following eight years. Sleep fragmentation was defined using an index of the number of sleep stage transitions per hour of sleep. In addition to a composite transition index, indexes of each of the six types of transitions were also tested.
The relative risk of death as a function of each transition index was calculated using proportional hazards models, adjusting for age, gender, body mass index, race, hypertension, cardiovascular disease, smoking status, respiratory disturbance index and arousal index.
According to the authors of the study, obstructive sleep apnea (OSA), a major cause of sleep fragmentation, has been linked to increased risk for all-cause mortality; however, most studies have not directly measured fragmentation. Findings of this study were able to directly measure the relationship between sleep fragmentation and mortality.