This may/may not apply to you. I've wrestled with a (not medically proven) condition called candida. Basically too much such/alcohol/yeast causes a yeast build up in my GI tract. This causes major issues like:
- fatigue (I was falling asleep at my desk at 10:30am after 11 hours of sleep)
- "Brain fog" (Best definition I've heard, it's the lack of the ability to focus after about 10 minutes etc)
- Depression (This came on when I would have too much sugar. It would really mess with my head)
Anyways, after some anti-fungals and cutting out most sugars from my diet, I'm 80% better now. I can put in a full day's work and can hang out at night without feeling repercussions the next day.