I've been hearing from acquaintances about German soldiers during WWII, including Hitler himself, were constantly using methamphetamine as an energy booster. That it was even recommended and deemed safe by doctors themselves.

by WeHighAssPlanes

I was having a conversation with some friends couple days ago about this. They showed me some gifs and you can clearly see Hitler jittery af and twitching. How true was this?

Georgy_K_Zhukov

More can be said on this, but this answer by /u/commiespaceinvader is a good starting point.