I sleep about 5-6 hours on average. Generally, I feel well rested with this amount, but I can function on 3-4 hours per night for a few weeks without serious il

I sleep about 5-6 hours on average. Generally, I feel well rested with this amount, but I can function on 3-4 hours per night for a few weeks without serious ill effect. I just feel slightly groggy, although at the end, I will have a "hard crash" where I sleep more than 12 hours. If I'm ill, I will sleep 8-10 hours a night. I think this is mostly genetic, because my father has been going to bed at 9 or 10 PM and waking up at 3 AM for as long as I can remember. I usually stay up later, but sleep about the same amount.