I'm allergic to drugs....
They make me break out in handcuffs.
I haven't been high in seventeen years and some change. So, I can't say what effect it had on me in the studio. However, I can say that Marijuana and LSD both really had an impact on my appreciation of music. In fact, it wasn't until I listened to it on acid that I finally understood Eric Dolphy's Out to Lunch. Also, listening to "2,000 Light Years from Home" while I was baked to a deep crisp was also a very pivotal moment. And listening to "Super Session" on acid was the seed that made me want to own a B3 since I was a teenager, not to mention that Harvey Brooks's bass playing on that really made me understand how important bass, and how it functions within a song.
However, I have a hard enough time functioning at what I would consider even 75% efficiency when I'm not stoned. I can only imagine that it would be worse. In fact, when I was fifteen, I worked a summer job at a hotel where they had an old phone system with a patchbay, and I got stoned at lunch one day. I fucked that whole thing up. If I couldn't operate a phone patch bay while stoned, imagine having to deal with one of my spaghetti nightmares that my bay can turn into on a tracking or mixing session.