The Sleepless Ape: The Story of Sleep in Human Evolution

by David R. Samson

How the unique sleep habits of early humans fostered survival, innovation, and social evolution—and how this evolutionary legacy holds insights into how we sleep today

Despite sleep’s critical role in maintaining health and cognitive function, humans sleep less than any other primate. The Sleepless Ape reveals the reasons for this evolutionary paradox, showing how our unique sleep patterns evolved when our ancestors left the safety of the forest for more dangerous ground, which led them to form more secure, social sleeping arrangements. As a result, early humans developed shorter, deeper, and more flexible sleep patterns that provided survival advantages and freed more time for crucial activities such as toolmaking, social interaction, and migration.

In this groundbreaking book, David Samson draws on his extensive fieldwork to explain how these sleep patterns contributed to our cognitive and social evolution. He delves into how the human brain adapted to achieve deeper, more restorative sleep, enabling advanced memory consolidation, fostering creativity, and contributing to our success as a species. Samson also addresses modern sleep challenges, demonstrating how an understanding of our evolutionary sleep heritage can help us to address sleep disorders and improve overall health and well-being. He tackles contentious issues such as co-sleeping, whether we should embrace paleo sleep or optimal sleep, and whether we are in fact suffering from an epidemic of too little sleep.

Blending the latest science with engaging storytelling by a leading expert, The Sleepless Ape shares compelling insights into how a fundamental yet overlooked aspect of human biology has shaped our evolutionary trajectory and continues to profoundly influence our daily lives.

Genres: Science

336 pages, Hardcover

Published May 19, 2026

About the author

DAVID R. SAMSON is an associate professor of Biological Anthropology at the University of Toronto. An interdisciplinary scholar investigating major behavioral and physiological transitions in human evolution, he has worked with a range of primate species and studied sleep in different types of human societies. Samson’s research has been internationally profiled in venues such as BBC, Time, the New York Times, The Smithsonian, CBC, NPR, and National Geographic. He is the Author of "OUR TRIBAL FUTURE: How to Channel Our Foundational Human Instincts into a Force for Good." In his spare time, Samson is a practitioner of a medieval martial art in the Society of Creative Anachronism.