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Sleep is governed by two systems—the circadian clock and the sleep homeostat. While the circadian clock is quite well understood, very little is known about the sleep homeostat.
Professor Gero Miesenböck, in whose laboratory the new research was conducted, explained: 'The circadian clock allows us to anticipate predictable changes in our environment that are caused by the Earth's rotation. As such, it makes sure we do our sleeping when it hurts us least, but it doesn't speak to the mystery of why we need to sleep in the first place.