I think this is looking at sentiment from interviews not objective results. It's common for these substances to make you think you're performing better but act

I think this is looking at sentiment from interviews not objective results. It's common for these substances to make you think you're performing better but actually that may not be the case. (Though the use of caffeine is pretty ubiquitous and it's hard to deny at least short term improvements there, at least until it starts messing with sleep)