Sleep apnea sufferers may benefit from the main ingredient in a poisonous African bean. The drug is called physostigmine. It’s the main ingredient of the deadly Calabar bean, once used in Africa in trial-by-ordeal rituals. Physostigmine is used as an antidote for organophosphate poisoning and also to treat certain types of glaucoma. Now it may help treat people with obstructive sleep apnea.