A prospective global cohort study suggested that total sleep duration of 6–8 h per day is associated with the lowest risk of deaths and major cardiovascular events (MCEs). Daytime napping is associated with increased risks of MCEs and deaths in those with >6 h of nighttime sleep but not in those sleeping ≤6 h/night. The study included 116 632 participants aged 35–70 years from seven regions worldwide. There were 4381 deaths and 4365 MCEs recorded after a median follow-up of 7.8 years. Both shorter (≤6 h/day) and longer (>8 h/day) estimated total sleep durations were associated with an increased risk of the composite outcome when adjusted for age and sex. Compared with sleeping 6–8 h/day, those who slept ≤6 h/day had a non-significant trend for increased risk of the composite outcome [hazard ratio (HR), 1.09]. As estimated sleep duration increased, there was a significant trend for a greater risk of the composite outcome (HR of 1.05, 1.17, and 1.41 for 8–9 h/day, 9–10 h/day, and >10 h/day, respectively). The results were similar for each of all-cause mortality and MCEs. Daytime nap duration was associated with an increased risk of the composite events in those with over 6 h of nocturnal sleep duration, but not in shorter nocturnal sleepers (≤6 h). The findings are consistent with previous studies and provide important epidemiological information. Source: https://academic.oup.com/eurheartj/
