Michel Siffre from the Sorbonne spent 63 days in a dark and icy cave, cut off from clocks, sunlight, and conversation. When he emerged in a disoriented fog, he realized that his perception of time had unraveled way more than he had expected.
The curious results from his subterranean stay turned into a whole new chapter in the study of chronobiology, which examines how living creatures keep time within their bodies.
Michel found himself at the center of a movement that would later connect to everything from jet lag to space travel.
A surprising pursuit
In 1963, Siffre planned to stay underground for 15 days to study a glacier.
He soon realized that this time would not be enough, so he decided to push past normal limits and live beneath the surface for more than two months, relying on basic supplies and no…