I read somewhere that Einstein only slept for 15 minutes every 2 hours and that he felt it cleared his mind and thought processes.  I, however, need a good 7-8 hours to feel fully rested but can function on some level with more or less, certainly not to my peak potential though.  Perhaps clarity of mind equaled hallucinations brought on by sleep deprivation?  Perhaps we should all try that.  When I was 12 or 13, I clearly remember staying up all night, night after night with my best friend giggling about stupid things and eating candy and chips.  A good friend of mine iis 20 and she stays up night after night going to clubs and out with friends, drinking outrageous amounts of alcohol and going to work the next morning at 8:30am.  I have 2 drinks, feel lightly nauseous, and miserably tired at about 11pm.  On the bright side, I'm up and ready to go at 6am every single morning no matter how much (or little) sleep I've had.  The only difficulty comes at 9am when a wave of tiredness washes over me if I've had less than that 7 hours.  Could I be (perish the thought) ..a morning person!?