Good question, as sleep is the time in which the body regenerates. Experts therefore recommend 8 hours. This corresponds to a third of our life. Some people might consider this too much, as they do not like the idea to sleep off so much off their lifetime. Maybe 6 hours are sufficient, even only 5 in summer. Whoever can have a short nap during the day, can certainly manage with less sleep during the night.
2 facts are clear: Firstly: If you do not sleep enough, you will notice it. Secondly: It is less important how much you sleep than how well you sleep.
Do not force yourself to sleep less, listen to your body instead. It is always the best indicator and will tell you how much sleep it needs - simply rely on that.