The Impact of Sleep on Longevity [Sleep and Health] Sleep is essential for good health, but staying up late increases disease risk. However, a recent study claims that "the earlier you sleep, the earlier you die," contradicting our understanding of the benefits of sleep. [Controversial Study] Researchers studied 112,198 participants from 21 countries for 9.2 years. Participants were divided into three groups: early sleepers (6-10 pm), normal sleepers (10-12 pm), and late sleepers (after 12 am).

Early sleepers had a 29% increased risk of death or major cardiovascular events, while late sleepers had an 11% increased risk compared to normal sleepers. [Research Findings] The reliability of the study is questionable due to sample selection bias. Developed countries with longer life expectancies had fewer participants in the early sleep group, while less developed countries with shorter life expectancies had more participants.

This might explain the association between early sleep and early death. [Criticisms of the Research] The University of Oxford found that the best bedtime for reducing cardiovascular disease risk is between 10-11 pm, while sleeping after midnight is associated with the highest risk.

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