Why is it that i feel sad for no reason?

Depression possible: It's possible that you're depressed -- many depressed people cannot point to a specific reason "why" they feel as they do. Sad mood and loss of interest in usual activities accompany changes in energy, appetite, and sleep. Also there is negative thinking and sometimes suicidal ideas. Help is available -- start with your primary care physician, who may also want a psychiatrist involved in your care.

Depression: Get busy with ur studies, have high goals, do exercise, avoid being alone. if no improvement see ur MD