I need much more sleep than I used to need when I was younger. At 64, I need at least eight hours but rarely get it because I sleep for shorter periods of time at a stretch. I wake up at 3 or 4 AM and lie awake for an hour or two, then fall back asleep into a deep sleep until 8 or 8:30. If I get up at 5 or 6 I'm tired for the rest of the day even with seeveral naps. When I manage to get my eight hours I still nap two or three times during the day. When I was young I could funtion perfectly well on five or six hours of sleep.