A study published in the December 1 issue of the journal SLEEP is the first to show that both a decrease and an increase in sleep duration are associated with an elevated risk of mortality by cardiovascular and non-cardiovascular means, respectively.
The study, authored by Jane E. Ferrie, PhD, of the University College London Medical School in London, U.K., focused on 10,308 participants between 35 and 55 years of age. Baseline screening (Phase 1), conducted between 1985 and 1988, involved a clinical examination and a self-administered questionnaire. Data collection at Phase 3 (1992-1993) also included a clinical examination (8,104 participants) and questionnaire (8,642 participants).
According to the results, U-shaped associations were observed between sleep at Phase 1 and Phase 3 and subsequent all-cause, cardiovascular and non-cardiovascular mortality. A decrease in sleep duration among participants sleeping six, seven or eight hours at baseline was associated with a 110 percent excess risk of cardiovascular mortality. However, an increase in sleep duration among those sleeping seven or eight hours at baseline was associated with a 110 percent excess risk of non-cardiovascular mortality. Adjustment for the socio-demographic factors, existing mortality and health-related behaviors measured left these associations largely unchanged.