Depression has a bad effect on my concentration. I have learned to study when I feel better and to study slowly when I feel bad, knowing I won't remember as much then. The extremes of heat and cold also affect me: they make my depression much worse and my concentration decreases. So I try to avoid extremes, but it is virtually impossible. Then about two weeks before classes are over, my level of interest and concentration just rolls over and kicks its legs up in the air. Once I discovered that, I have learned to study a little all along so that even if I do less well on the last exam, my grade stays high.