Occasional/moderate stimulation of this sort can be a big boost to concentration, just like a change in your daily environment. However, I wouldn't rely on it! Enjoy a drink or a smoke in moderation for pleasure, and if you feel moved to do work (and have a backup...) then great. But if you need to do work and must smoke a cigarette or something to get in the mood, then you are on the way to an unhealthy addiction.