Article siffre1

Published on August 7th, 2013 | by Dan Walsh


The Timeless Sleep Cave

In 1962, Michel Siffre conducted an epic experiment on sleep and the human perception of time. He cloistered himself in a cave for 63 days without clocks or any other cues about the passage of time. He ate when he got hungry and slept when he was tired.

My sleep was perfect! My body chose by itself when to sleep and when to eat. That’s very important. We showed that my sleep/wake cycle was not twenty-four hours, like people have on the surface on the earth, but slightly longer—about twenty-four hours and thirty minutes.

He also proved that humans have an internal biological clock.

In fact, it became common… to achieve cycles lasting forty-eight hours: [The later subjects] would have thirty-six hours of continuous activity followed by twelve to fourteen hours of sleep. After we made that discovery, the French army gave me lots of funding.

The study also revealed interesting relationships between the amount of time a person is awake and asleep.

We showed that there is a correlation between how long a person stays up and how much he dreams the next night. Roughly speaking, for every ten extra minutes of activity each day, a man gets one extra minute of REM sleep… We also found that the more you dream, the shorter your reaction time during your next phase of wakefulness.

This is pretty much the most awesome experiment I’ve ever heard of. Siffre experimented on sleep, in a cave, and discovered secrets about the human perception of time. Egads!

Read: Caveman: An Interview with Michel Siffre, by Josh Foer

Image: From Siffre’s 1972 experiment in Texas.

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2 Responses to The Timeless Sleep Cave

  1. Angelica says:

    I am really shocked by the 48 hour cycle. I can sleep for 12-14 hours no problem, but there’s no way I could have stayed up for the prior 36 hours. I might have to give this an experimental try and report back.

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