Astronauts often spend extended periods of time away from home and even more time in isolation. As such, they are predisposed to Solipsism Syndrome. This is a psychological state in which the person does not believe the world is “real.” They do not believe that it exists external to his or her mind. The syndrome is characterized by feelings of indifference, loneliness and detachment. The American Psychiatric Association does not currently recognize it as a psychiatric disorder.
It does have similarities with depersonalization disorder though, which is a recognized disorder. This syndrome is different from solipsism, which is a philosophical position rather than a psychological state. People who take this position do not believe that anything exists or can be known to exist outside of one’s own mind. The fact that astronauts and cosmonauts are predisposed to this syndrome influences the design of their artificial environments.