I think sleep needs vary tremendously by individual. I have always been a light sleeper and also have always slept 9 to 10 hours a night. When I was a teen it was 10 now that I am 65 it is 9. If I only get 7, I can function but will feel awful.
My Father was really strange. He could lie down just about anywhere and immediately go soundly to sleep. I could never do that.
I have a friend who was a Navy pilot for years and then a
commercial pilot until retirement. He never got into a sleep
pattern. He could sleep and be up on about any schedule as
long as the rest averaged out well. He could do this.