Is Sleep Sustainable?

I was just having a conversation with my family this week about sleep and how much sleep is the right amount to get. And obviously it's very different for everybody, but i find that personally, seven hours asleep as is like right in my wheel house. If i get any more, if i get eight plus hours a sleep, i tend to be over tired. I wake up more groggy than i would otherwise. Where do you fit in that realm? And what have you heard about sleep in terms of well being in the studying that i have done?