Sleep duration is a strong behavioral risk factor for mortality, with sleep durations ≥10 hours holding the greatest association with mortality for both men and women, suggests a study published in JAMA Network Open. The findings also indicate age is a modifier of the association between sleep duration in men.
The study was an analysis of individual-level data from 9 cohorts in the Asia Cohort Consortium performed between 1984 and 2002. A total of 322,721 people (mean age, 54.5 years) from China, Korea, Japan, and Singapore were included in this analysis. The mean follow-up duration was 14.0 years for men and 13.4 years for women.
Researchers evaluated the association between mortality and self-reported sleep duration, with 7 hours representing the reference category. The mortality outcome included deaths from all causes, cardiovascular disease (CVD), cancer, and other causes.
Over the follow-up period, a total of 19,419 deaths were reported in men (mean age, 53.6 years) and 13,768 deaths in women (mean age, 55.3 years). In the pooled analysis, the mode sleep durations for men and women were 8 and 7 hours, respectively. Men and women showed an association between sleep duration and all-cause mortality that was J-shaped.
According to the researchers, the greatest association for all-cause mortality was with self-reported sleep durations lasting ≥10 hours in both men (hazard ratio [HR], 1.34; 95% CI, 1.26-1.44) and women (HR, 1.48; 95% CI, 1.36-1.61).
While sex was not a modifier of sleep duration for all-cause mortality (P =.12), this variable was a significant modifier of the association between sleep duration and mortality from CVD (P =.02), cancer (P =.007), and other causes (P =.03). Among only men, age was found to be a significant modifier of the associations of sleep durations and all-cause mortality (P <.001) cancer (P <.001), and other-cause mortality (P <.001).
Study limitations included the reliance on data from self-reported questionnaires, which the researchers suggest may have resulted in overestimated sleep durations, particularly in people who sleep less.
The researchers wrote that their “findings suggest that sleep duration recommendations for East Asian populations may need to be considered in the context of sex and age.”
Svensson T, Saito E, Svensson AK, et al. Association of sleep duration with all- and major-cause mortality among adults in Japan, China, Singapore, and Korea. JAMA Netw Open. 2021;4(9):e2122837.