The military can be a harrowing, character building experience. People are pushed to their limits, and at a moment’s notice they can be deployed to a country that most of us have never heard of and face horrors that none of us will ever understand.

After World War II, U.S. and British governments ordered their soldiers to take LSD and run through drills, and then compare their performance to that of someone who completed the drills sober. But while high on LSD, the soldiers burst out laughing or even climbed trees.

The CIA program code MK Ultra tested on mental patients, drug addicts, and prostitutes against their will. Researchers found that LSD made people happier, more relaxed, and less afraid of death. Though there were exceptions, like bad trips.

See also: 9 Movies and TV Shows Inspired by MK Ultra