Why do i feel so depressed ?

i feel extremely depressed when i wake up. I already sleep very little. It lasts about 5 hours or less, but till the time im already in depression. I don't know why i feel like that. I just can't understand. I was depressed some 2-1 years ago but it faded. Now though i feel bad. I don't feel suicidal compared to the last time. I did tried to harm myself,i did OD and many things. I know i'm not okay but i'll fight. I feel like i'm sick and will die,but truth is i'm okay.i haven't got any illness.