How much sleep do you need?
My usual is 7.5 - 8 and I try to stick to that even during time off from work.
My intention is to keep my circadian rhythm balanced, healthy, or whatever the word is for it. I also strive to keep the same sleep schedule, even on weekends.
I am grateful that I almost never feel sluggish or tired.
Need or want? When I was working I went to bed at 10, read a half hour and up by 5. That seemed plenty. Now it's in by 9ish, read a half hour and up around 6ish (depending how much time I lay awake thinking about issues from agnostic.com which is usually too much). Winters I get more and summers less. At my latitude it is darker longer in winter but summer the sun doesn't set until after 10 and rises at 4.
6 to 8 hours. in my opinion. My fiance was suffering from insomnia at night, so he tried just getting naps in , here and there, to make up for his nighttime loss of sleep. His Psychiatrist told him that was fine , as long as it totaled up to at least 6 hours per 24 hour period. I disagree. I feel a good recharging of your body needs to be in one long sleep, with maybe a 1/2 hour nap during the day if you're super tired. Well, I don't know if it was depression that led to his sleeplessness, or his sleeplessness that led to his depression, but he couldn't take it anymore and committed suicide last Fall. Sleep is serious stuff.