From Last 2 Yrs I Am Feeling Restless And Annoyed

from last 2 yrs i am feeling restless and annoyed . i always feel like crying without any reason . from last few 2 yrs i am not able to get happy from my inner heart . i always feel like dying only . at night i am not able to sleep well. and moreover i am not able to concentrate on my studies though i try to study harder and harder. are these symptoms of depression??