NSF leads research and public guidance on sleep health; current debates spotlight duration norms and sleep quality across demographics.
A Brain Medicine review suggests eight hours may not be essential for all adults. Analyses of hunter-gatherer groups and pre-industrial societies show natural sleep ranges between 5.7 and 7.8 hours, with a typical average around 6.4 hours. Researchers caution that modern sleep needs vary by health, sex, and environment, challenging the one-size-fits-all eight-hour rule.