Caffeine certainly is a good, tame example. It's chemical effect is basically to block your brain from fatigue signals, perhaps analogous to anesthetic that blo

Caffeine certainly is a good, tame example. It's chemical effect is basically to block your brain from fatigue signals, perhaps analogous to anesthetic that blocks pain signals. It doesn't actually prevent fatigue, just as anesthetic doesn't actually prevent injury or damage. You are still burning through energy and accumulating sleep debt like anyone else.