I've noticed that whenever I'm shutting off for any reason (depression, escape from stress, or simply lack of sleep) drinking beer perks me up and helps me stay functional the whole evening just like coffee does, but in a much more pleasant way. It's tough to abstain from a simple solution like that and just get the needed R&R instead. The downside is that the next day I'm almost as tired as if I had drunk coffee all evening and tossed and turned all night.