As a hacker you can probably get away with it. If you're a 10x hacker, maybe you'll be an 8x hacker that's less stressed and more happy. Depending on how you handle stress, maybe you'll be more effective overall. It's a tradeoff you can make with yourself. (Be sure to stay legal and get a prescription.)

While you're leading a company, don't. Being a good leader requires a great memory. If you forget half of what was said on Fridays because you smoked that night, you're hosing everyone.