During World War II, the method was „learning during sleep“ is already used as part of the American defense organization to train (Office of Strategic Services), secret agents and train. In this case the agents were learning during sleep taught foreign accents, habits, customs, dates, names, etc. that were for their effective use in enemy territory is very important. Also other official bodies such as the air force, the navy and the army did with the sleep-learning method successful attempts.
Agents learn in sleep