I have been a regular drinker for most of my adult life.
Recently, I tried a "semi-dry July", where I told myself I would drink only once a week (with no limit on that day, i.e. binge drinking allowed). But when I got to that day, I felt only like having one beer or so, and same the following week.
Well, here's an amazing thing, shocking and totally counterintuitive: I felt much better while doing this than I did for years before that. My mental acuity went up noticeably, and was much longer lasting - I would wake up at 7am and feel mentally sharp within 15 minutes, and stay mentally sharp all the way to 10pm or so.
I was forced due to holidays and social circumstances to resume drinking in August. Well, now that the social circumstances and holidays are out of the way, I've gone back to not drinking. I'm still in the ramping up phase, and every day I feel better than the last.
I strongly recommend giving this a go to pretty much everyone on Hacker News: try going a month without alcohol, see how you feel.
Oh, I'll add that near the end of "semi-dry July", I had one instance where I had a couple of pints with a friend (social pressure!). I could feel that my brain was noticeably less sharp and my motivation was noticeably down compared to before. That lasted 2.5 days. TWO AND A HALF DAYS!
My conclusion: When you don't drink, it's as if you hired an extra one of you to work on your business. When you do, it's as if you fired that extra person. Are you resource-constrained? Stop drinking. You'll save money too - bonus!