I often get 4-6 hrs. of sleep because of everything I must do or want to do. But when I wake up, I'm fine. Everyone says you need a min. But I don't think that is true.
Sleep is mostly pschyological.
If you think you need sleep, then you will need sleep. If you can reach this point, then that is all you need. The truth is, there is too much to do in life to be wasting 8 or more hrs a day on sleep. I agree, some sleep is needed. But not 8 hrs day after day.