It may be the weed...do you drink coffee or any caffinated beverages? They might have something to do with your anxiety too, since anxiety and depression are side-effects of caffeine withdrawl..personally I feel alright the next day after smoking, I don't feel depressed or anything, i feel more like that after a lot of caffeine..actually come to think of it, ive been going through the damn caffeine anxiety all day today..which is why i'm not drinking any coffee or soda (i dont even drink soda at all to begin with) today.