Michel Siffre and the Birth of Human Chronobiology
In a bold experiment, Michel Siffre of the Sorbonne spent 63 days in a cold, pitch-black cave, isolated from clocks, sunlight, and human contact. When he finally surfaced, dazed and disoriented, he was stunned by how far his sense of time had slipped. His experience would become a cornerstone in the field of chronobiology – the science of how organisms regulate time internally.
Originally, in 1963, Siffre had planned a brief 15-day stay underground to study glacial formations. Realising the opportunity to explore something deeper, he extended his isolation to over two months, surviving on minimal supplies and abandoning all external cues for time. “I was a geologist by training,” he explained, but this foray into darkness led him into uncharted scientific territory. Free from natural markers, he carefully recorded his daily habits as the outside world moved on without him.
What he uncovered was astonishing: the human body has its own internal rhythm, separate from the 24-hour day. Deprived of light and routine, his circadian rhythm gradually extended, proving that our internal timekeeping system is more flexible than previously thought. “Without realising it,” he later said, “I created the field of human chronobiology.” His findings showed that, without environmental prompts, our biological clock drifts – a revelation with wide-reaching implications.
Others followed Siffre’s methods and encountered similar shifts in sleep-wake patterns. Some remained awake for 72 hours straight or slept for up to 33 hours, defying conventional cycles. In one case, a subject with a microphone alarmed researchers when he stayed silent for over a day, raising fears of death. Such results confirmed that the body’s timekeeping system can behave erratically in isolation.
At the height of the Cold War, Siffre’s work caught the attention of NASA,
