I don't notice any mood changes with coffee or energy drinks and I don't smoke but I eat sweets for my good mood. Sugar for me is the best antidepressant there is. I know it is bad just like cigarettes but it allows me to function when I otherwise would be too depressed to do so. I am able to workout, run errands, clean house, etc plus I feel happy. I love the sugar high. Yes it is bad but like you said why should you give up the one or two things that you have that you enjoy? That is just my take. I don't think too much about the future. If I was getting the same high from cigarettes I would continue to smoke and not think that oh I better quit becuase I might end up hooked up to oxygen. When a person is mentally ill, suffering day in and day out with depression and they can get a little bit of joy from one or two things, be it coffee, cigarettes, sugar, I say go for it, we have a hard enough time in life to worry about long term consequences.