If you do not have to signal that it's time to go to sleep, your sleep-wake cycle is 25 hours instead of 24

People can be programmed to wake-sleep cycle than the standard dvadtsatichetyrёhchasovogo that will not strictly synchronized with the change of day and night.

In 1938, two men, Nathaniel Kleitman and Bruce Richardson, decided to find out what cycle adhered cavemen - in other words, to understand how to become this cycle, if there were no signals when to sleep and when to wake up.



They decided to move to a perfect place for the experiment, which would be completely isolated from the outside world - a cave and live in the same rhythm as the prehistoric cavemen. Kleitman and Richardson remained in the cave for 33 days, going to bed and getting up only when the body is like that.

As a result, they found a very strange feature, and subsequently confirmed by other studies. It was found that when the body is given to itself and no external factors will not affect the decision of the dream, it tends to a cycle of 25 hours, rather than 24, as is customary throughout the world.

via factroom.ru