A French scientist emerged from a cave after 63 days living in total isolation away from natural light on September 14, 1962.

Michel Siffre had nothing more than a four-volt lamp for illumination in his two months underground.

Though a trained geologist, his time underground had nothing to do with rocks.

Instead, he was conducting an experiment on how the body clock operates without sunlight.

And quickly, he stopped operating on the same sleep cycle as everyone on the surface.

His waking hours began to extend to 25 hours.

Consequently, his two months underground felt to him more like one.

"After one or two days, you don't remember what you have done a day or two before," he told Cabinet magazine.

"The only things that change are when you wake up and when you go to bed.

"Besides th

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