Mental health problems can affect a student's energy level, concentration, dependability, mental ability, and optimism, hindering performance.

Research suggests that depression is associated with lower grade point averages and that co-occurring depression and anxiety can increase this association. (National Institute of Mental Health)

If students continue to suffer mental illness in school you will see them struggle a lot because they are not mentally there and school is just stressing them even more so it causes a lack of energy, doing badly in school and wrong behavior, etc.