People who have been deprived of sleep apparently appear less attractive than those who are well rested- (source)
Sleep repairs and heals your body which is why you should use your most active skin creams at night- (source)
It is said that we should be sleeping roughly 7 1/2 hrs a night- (source)

Most nights, I do sleep an average of 7-8 hours. I find that the nights I get about 6 hrs of sleep, I’m more awake than nights that I get 8 or more hours of sleep.