Mortality from Aortic Disease in Relation with Sleep Duration at Night and Daytime Napping: The Japan Collaborative Cohort Study.

Aims: Few studies have investigated the impact of sleep duration at night and daytime napping on mortality from aortic disease. In this study, we examined the associations of sleep duration at night with daytime napping and mortality from aortic disease.

Methods: We followed 67,269 participants (26,826 men and 40,443 women, aged 40-79 years) who were not night shift workers and had no history of stroke, heart disease, or cancer. The baseline survey was conducted in 1988-1990, and follow-up continued until the end of 2009. Sleep duration at night was classified into three categories: ≤ 6, 7, and ≥ 8 hours/day. We also asked the presence or absence of daytime napping. Hazard ratios (HRs) for mortality from aortic disease with 95% confidence intervals (CIs) were estimated using the Cox proportional hazards model.

Results: During an average 16.3-year follow-up period, we observed 87 deaths from aortic dissection and 82 from aortic aneurysms. There was no association between sleep duration at night and mortality from aortic disease, but daytime napping was associated with an increased risk of mortality from total aortic disease; the multivariable-adjusted HRs were 1.48 [95% CIs: 1.08-2.02]. Furthermore, the stratified analysis revealed a stronger association with medium sleep duration (7 hours at night) compared to the other shorter and longer sleep duration: the multivariable-adjusted HR for aortic disease, 2.02 [1.16-3.52].

Conclusion: Daytime napping but not sleep duration at night was associated with an increased risk of mortality from aortic disease.