Association of estimated sleep duration and naps with mortality and cardiovascular events: a study of 116 632 people from 21 countries

Estimated total sleep duration of 6-8 h per day is associated with the lowest risk of deaths and major cardiovascular events. Daytime napping is associated with increased risks of major cardiovascular events and deaths in those with >6 h of nighttime sleep but not in those sleeping ≤6 h/night.