
Episode #123
Episode 123: The Human Sleep Paradox: Why We Sleep Less Than Every Other Primate with Dr. David R. Samson
What if the biggest problem with modern sleep isnβt duration, but disconnection? Dr. David R. Samson, evolutionary anthropologist and author of The Sleepless Ape , joins Dr. Jeremy Koenig to explain why humans sleep less than every other primate studied, yet devote an unusually large share of that sleep to REM. They explore what sleep among the Hadza reveals about circadian health, how early humans built a protective βSHELLβ around sleep, and why light, temperature, social structure, and evolutionary history may matter more than chasing a universal eight-hour target. Key Takeaways Humans are evolutionary outliers: comparative models predict we should sleep roughly 11.5 to 12 hours, yet we sleep far less than other primates. Data from 54 populations found that small-scale societies averaged 6.4 hours of sleep, compared with 7.1 hours in large-scale societies. β±οΈ Sleep efficiency averaged 74% in small-scale societies and 88% in large-scale societies, challenging the idea that industrialized populations universally sleep worse. βοΈ Small-scale societies showed stronger circadian function, pointing to regular exposure to natural light and temperature as a major advantage. Samsonβs SHELL framework covers Shelter, Hearth, Environmental preparation, Lux, and Lookouts. οΈ During 20 days of Hadza observation, everyone was simultaneously scored asleep for only 18 minutes; a median of eight people remained awake at any given nighttime interval. Intergenerational chronotype variation may have created a natural security system, with older βlarksβ and younger βowlsβ covering different parts of the night. REM sleep helps regulate emotion, while slow-wave sleep supports immune function, placing a biological floor on how far humans can safely reduce sleep. Connect with Dr. David R. Samson Website: davidrsamson.com University of Toronto: Sleep and Human Evolution Lab Instagram: @primalprimatologist X: @Primalprimate LINKS: https://www.drjeremykoenig.com/ https://www.instagram.com/drjeremykoenig/ https://www.youtube.com/@drjeremykoenig Here's the link for this week's episode: https://drjeremykoenig.substack.com/ .






