Erdos famously took amphetamines his whole life, and they made him fabulously productive:

> In 1979, Graham bet Erdös $500 that he couldn't stop taking amphetamines for a month. Erdös accepted the challenge, and went cold turkey for thirty days. After Graham paid up--and wrote the $500 off as a business expense--Erdös said, "You've showed me I'm not an addict. But I didn't get any work done. I'd get up in the morning and stare at a blank piece of paper. I'd have no ideas, just like an ordinary person. You've set mathematics back a month." He promptly resumed taking pills, and mathematics was the better for it.

I think about this a lot. I drink a lot of coffee and I feel reasonably productive. But hey, maybe I should try something a bit stronger... :