What Causes Exhaustion Throughout The Day Even After Good Sleep?

I am 20 years old. Throughout all 4 years of highschool I was able to maintain functionality with only 4 hours of sleep. Now, 2 years later I feel so tired no matter what. I average 8-10 hours of sleep because I try to make sure i'm rested. Even after 10 hours of sleep i'm just exhausted throughout the day.



My arms feel heavy, my eyes are always dark, i usually feel a little light headed, and i'm just not as alert as I used to be.