It may not seem like it, but sleep deprivation affects your intellect significantly. For example, according to reaction time test results, sleep deprived individuals have slower reaction times than intoxicated individuals! Performing well in school would be difficult with that same kind of mental condition.
So, make sure you get 7 - 9 hours of sleep each night, even on weekends. It helps to establish consistent sleep and wake schedules. Unlike money, you can't save up sleep and borrow from it later. You need to sleep enough and consistently; catch-up sleep doesn't work.