There are the so-called "short sleepers" who need less than 5 hours of nightly sleep
to function normally.
There are the so-called "long sleepers" who need more than 10 hours of sleep. Both are considered variants of the normal. Most of adults will be somewhere in between: needing 5-10 hours of sleep. Hope, this 20 year old functions normally during the day after 10 hours of sleep.