Where human sleep went wrong
Nautilus has a great interview with David Samson, author of The Sleepless Ape. His claim: we are the shortest-sleeping primate on the planet, our sleep is mostly fine, and the eight-hour rule was never biology — it was a labor negotiation.
Samson is an evolutionary anthropologist, and his starting point is a genuine puzzle. Humans are the shortest-sleeping primates ever recorded — the owl monkey does 17 hours, we cluster just under seven — yet we pack in the most REM relative to that short duration, and we are arguably the most successful primate anyway. Sleep is critical to cognition, immunity, and emotional regulation. So how did the species that needs it most end up with the least of it?
The Hadza sleep badly and love it
His field work with the Hadza in Tanzania undermines two orthodoxies at once. Their sleep is short, fragmented, and low-efficiency — people stay up late telling stories and dancing — yet 98 percent report being happy with it. So much for the paleo sleep fantasy, and so much for the idea that unbroken sleep is sacred.
The variable that actually matters seems to be circadian amplitude, not duration. Small-scale societies show much stronger circadian rhythms than we do in the global north. Six and a half hours with strong circadian function feels fundamentally different from the same six and a half with weak function. Duration in isolation tells you very little.
Where the eight hours came from
The key message of the whole interview is where the eight-hour norm comes from. Not biology — post-industrial labor negotiations. Unions argued that a third of the day should be set aside for rest, and eight hours was the floor carved out at the bargaining table. That negotiated number then hardened into folk wisdom and medical orthodoxy.
The eight-hour norm is not biology. It is a floor carved out in negotiations over time away from work.
Samson calls the result the lie-down-and-die model: one rigid block of sleep in service of the 9-to-5, with anything more flexible or polyphasic treated as a disorder — because a flexible sleeper threatens the rigid workday, not because their sleep is broken.
Hold the gains, fix the signals
The practical takeaway is almost boring. Keep the plush beds and the 18°C bedrooms — those are genuine gains, and the West is averaging 7.1 hours, right in the sweet spot. But spend at least 15 percent of waking hours outside, anchor mornings with real daylight, avoid blue light after sundown. Give the body the light and temperature signals it evolved to expect.
