hard alcohol will change your brain chemistry in ways to mimic insomnia. this is part of withdrawals and usually the most lingering effect. but you usually get over it in a week or so. also, quality of sleep is diminished on the amount you've consumed. sure you pass out, but it is shit sleep ask me how i know, last time i withdrawls from booze i got about 3-4 hours of sleep for 3 days. Doesnt matter how tired you are, close your eyes WIDE awake... but this when you are sober maybe that is too honest, hmmm