Sleep science challenges the universal eight-hour sleep rule

New scientific reviews and research suggest that the long-standing ‘eight-hour sleep rule’ may not be a universal necessity for all adults. A narrative review published in Brain Medicine indicates that sleep patterns in pre-industrial societies were significantly more flexible than modern standards suggest.

Studies of hunter-gatherer communities in regions such as Tanzania, Namibia, and Bolivia have shown that individuals often sleep between 5.7 and 7.1 hours per night without the need for daytime naps. Other analyses estimate the average sleep duration in pre-industrialized societies to be approximately 6.4 hours.

Researchers note that individual sleep needs vary based on factors such as gender, age, and overall health. While modern artificial light from screens and lamps can disrupt the circadian rhythm, the biological requirement for sleep is not a fixed eight-hour block for everyone. To help stabilize the biological clock, experts suggest using ‘sleep anchors’—consistent daily habits such as regular wake-up times, exposure to morning light, and scheduled meal times.