I'm 25 and I require 8.5 hours of good sleep for optimal performance.
I did some benchmarking about three years ago by timing myself trying to solve similarly-challenging Sudoku puzzles in a Nintendo DS game. With good sleep, I'd consistently approach 14 minutes with zero mistakes. After about 2-3 days of not having good sleep, it would drop to 16-20 minutes with more mistakes. I would also consciously notice various effects like diminished memory recall, more stuttering, poor focus, etc.
I've also been hearing that the length of sleep required is typically reduced with age. I don't have any citation on this though, would love to read more on the topic if anyone has more insight.
I didn't focus on that but anecdotally I find that consistently oversleeping (over 9 hours) would leave me groggy and generally reduced performance (at least temporarily in the morning) but not as bad as sleep deprivation. Whereas getting one or two nights of mild oversleeping after being sleep deprived for several days does seem to speed up the recovery time.
Of course there were many other variables like exercise, diet, health, and mood, where each seems to have some minor effect on my sleep requirements one way or the other. The Sudoku benchmarking was performed on more or less "idling" lifestyle (no unusual healthy or unhealthy activities, and I wasn't consuming alcohol/caffeine or smoking).
I did some benchmarking about three years ago by timing myself trying to solve similarly-challenging Sudoku puzzles in a Nintendo DS game. With good sleep, I'd consistently approach 14 minutes with zero mistakes. After about 2-3 days of not having good sleep, it would drop to 16-20 minutes with more mistakes. I would also consciously notice various effects like diminished memory recall, more stuttering, poor focus, etc.
I've also been hearing that the length of sleep required is typically reduced with age. I don't have any citation on this though, would love to read more on the topic if anyone has more insight.