Here are a few things that you didn’t know about Sleep
Sleep is a naturally recurring state characterized by reduced or lacking consciousness, relatively suspended sensory activity, and inactivity of nearly all  voluntary muscles.  It is distinguished from quiet  wakefulness by a decreased ability to react to  stimuli, but it is more easily reversible than  hibernation or  coma. Sleep is a heightened  anabolic state, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. It is observed in all mammals, all birds, and many reptiles, amphibians, and fish.
The purposes and mechanisms of sleep are only partially clear and are the subject of intense research.  Sleep is often thought to help conserve energy,  but actually decreases metabolism only about 5†10%.  Hibernating animals need to sleep despite the hypometabolism seen in hibernation, and in fact they must return from hypothermia to euthermy in order to sleep, making sleeping “energetically expensive.” – wikipedia
