Scientific research challenges the universal eight-hour sleep rule

A scientific review published in the journal Brain Medicine challenges the long-standing belief that eight hours of sleep is a universal requirement for adults. Researchers suggest that the eight-hour recommendation may be an arbitrary average that does not account for individual variations caused by genetics, age, lifestyle, and circadian rhythms.

By analyzing sleep patterns in hunter-gatherer communities in Tanzania, Namibia, and Bolivia—groups living in pre-industrial conditions without artificial light—the study found that individuals slept between 6.4 and 7.1 hours per night. These participants reported feeling fully rested without the need for alarms or daytime naps, suggesting that modern urban sleep deprivation may be linked to artificial light and noise rather than a biological need for more hours.

While medical organizations still recommend at least seven hours of regular sleep to avoid metabolic, cardiovascular, and cognitive issues, the research indicates that both too little and too much sleep can be detrimental. One study noted that sleeping fewer than six hours or more than eight hours was associated with accelerated biological aging, with the lowest levels of aging observed in those sleeping between 6.4 and 7.8 hours.