i'm a heavy smoker. I by rule smoke only the last hour of game play, and only a little. I am forever DM...so I enjoy a little release. I find a little helps me be really creative and dramatic in my completing to the party. The party and I all eat big meal before session and have a simple drinking rule. you can drink in real life when you character drinks in game, only....we find it fun.

It's all about a session zero, what is everyone comfortable with and what do we owe each other during game play? libations are fine and encouraged especially on nights when we've also worked during the day. That said anyone drunk or too high ruins fun for everyone, no one is cool withsomeone tipsy drinking/driving to put that on us yo. Following these rules, after 100 games DM'd we've had a lot of fun and I can say substances ( beer or weed) have been used 80% of games.