Geologist's 63-Day Cave Experiment Reveals Surprising Effects on Circadian Rhythm and Sense of Time

On the morning of September 14, 1962, a gathering of reporters and spectators formed around an opening in the ground located in the Maritime Alps, straddling the border of France and Italy. A few hours later, workers lowered a rope into the abyss, and soon after, they extracted a stout figure, Michel Siffre, a geologist, who had been immersed in darkness 375 feet underground for a grueling duration of 63 days, with only a four-volt lamp providing feeble light.

Observing the Passage of Time

To mitigate the impact of the potential daylight exposure, Siffre donned dark goggles, and due to his weakened state, he required assistance to be transported to a helicopter awaiting his arrival. However, this was not a rescue mission; rather, Siffre was engaged in a self-experimentation to fathom the effects of isolation from the typical day-night cycle on his perception of time.

Remarkably, his experience of time underwent a significant alteration. He reported that his circadian rhythm of wakefulness and sleep had expanded from the typical 24 hours to approximately 25 hours. As a result, what he perceived as one month underground translated to an actual duration of two months on the surface. These findings revealed the remarkable adaptability of human perception and the malleability of the circadian rhythm under extreme isolation.