Enjoyment examines a number of writers and the drugs they used — and concludes with this:
Drugs provided a marvellously adaptable and popular subject matter for authors — as sexy, sensational or sordid as they wanted. It has been a more mixed story for literary drug users. Although authors who took drugs for pure pleasure were the most criticised, they usually did the least harm to themselves. Druggy authors trying to turn themselves into transcendental voyagers virtually always made fools of themselves. And some writers who used substances both to cope and to unwind, found they couldn’t handle the stuff, and did themselves harm. Others took the pills and went on working fine. Overall, then, authors were pretty much like everyone else.
I’ll stick to caffeine. In small doses.