Michel Siffre

Michel Augustin Francis Siffre (; 3 January 1939 – 25 August 2024) was a French geologist, speleologist and underground explorer. He is especially known for the chronobiology experiments he conducted on himself.

Early life, family and education

Siffre was born and raised in Nice, France. His parents were Jean and Lucie (Roques) Siffre.

Initially, Siffre was planning to study a newly discovered glacier from Nice by remaining within it for 15 days. However, inspired by the space race, he extended the duration and examined how humans experience time by spending 62 or 63 days below the surface in the abyss of Scarasson (Punta Marguareis) in the Maritime Alps between France and Italy. Subsequently, he designed or organized over a dozen underground experiments for other speleologists.

In 1972, Siffre performed a more extensive underground experiment, staying six months in Midnight Cave After the experiment, he concluded that without time cues, he adjusted to a 48-hour rather than a 24-hour cycle. In debt from the experiment's significant costs (even though some of it was paid through government funding),

Publications Hors du temps. L'expérience du 16 juillet 1962 au fond du gouffre de Scarasson par celui qui l'a vécue, Julliard, 1963 Des merveilles sous la terre, Hachette, cop. 1976 Stalactites, stalagmites, cop. 1984 L'or des gouffres: découvertes dans les jungles mayas, Flammarion, 1979 Dans les abîmes de la terre, Flammarion, 1975 La France des grottes et cavernes, Privat, 1999 A la recherche de l'art des cavernes du pays Maya, A. Lefeuvre, 1979 Découvertes dans les grottes mayas, Arthaud, 1993 Beyond Time, translated by Herma Briffault, McGraw-Hill, New York, 1964