Foreseen, controlled results could be an issue. Depending upon one's attitude toward any intoxicating substance, stimulant or depressive, the question is 'how much is just right?' As a corollary, 'how much is too much?'

Given the hundreds of stories about the hundreds of musicians that had/have 'problems' using drugs (including alcohol) to relax, calm jitters, boost creativity, etc., and the long list of musicians lost too early, such self-prescribed treatment sounds like a very bad idea. Finding a reason to justify some level of intoxication seems like a quick path to dependence. YMMV.

If one can't handle the guitar as well as the big boys and girls why would one think one could handle the self-medication any better?

When I close some of my posts with "have fun" sparking up was not what I meant.

Have fun.

john

p.s. good one, JeffS65