Radix
Michel Siffre (born 3 January 1939) is a French underground explorer, adventurer and scientist. He was born in Nice, where he spent his childhood.
He received a postgraduate degree at the Sorbonne six months after completing his baccalauréat. He founded the French Institute of Speleology (Institut français de spéléologie) in 1962 (not to be confused with the French Federation of Speleology).
Inspired by the space race, he explored how humans experience time by spending two months cloistered in the abyss of Scarasson (Punta Marguareis) without time cues on a glacier, from July 1962. He then organized several similar underground experiments for other speleologists. In 1972, Siffre went back underground for a six-month stay in a cave in Texas. He found that without time cues, several people including himself adjusted to a 48-hour rather than a 24-hour cycle. The notes of his experiments were used by NASA. Several astronauts reported experiences similar to those experienced in underground experiments such as loss of short-term memory to being isolated from external time references.