How does life under stressful conditions affect the immune system?

Living in space is a wonderful experience but it can take its toll on an astronaut’s body: half of astronauts return feeling sick from a mission to the International Space Station. Stress is a response of the body as it adapts to hostile environments. This broad definition includes stress from speaking in front of an audience, stress from a wound or stress from living in weightlessness in a fragile spacecraft far from home. The Immuno-2 experiment took a holistic approach to consider how stress affects our immune system. Using brain scans, monitoring breathing and looking at samples from astronauts' hair, the researchers hoped to understand how living in stressful conditions affected their immune system.