What is "asthenization"

In medicine, asthenization is a condition experienced by astronauts following long-term space flight, in which following return to Earth the astronaut experiences symptoms such as fatigue, irritability, lack of appetite, and sleep disorders. The condition's name derives from asthenia, which is a medical term denoting a feeling of weakness without actual loss of strength.

It is suspected to be a psychosomatic effect of the result of overachieving astronauts no longer having a goal after becoming astronauts, or potentially a neurological effect of microgravity. Buzz Aldrin, the second man to walk on the moon, was afflicted with this condition after returning from the moon.