“What kind of sleeper are you? Do you drop off like a stone and awaken refreshed, or do you need pitch black and silence to drift off to dream?” –The Daily Post
My face hits the pillow and I’m asleep on impact. I wake up five to six hours later and I’m 100% refreshed.
Typically I’ll wake up a little groggy if I only get two or three hours of sleep so I try to avoid that. Same with anything over six hours.