Stress and Immunity
Space flight conditions affect human health due to complex environmental challenges (“stressors”) which might be most pronounced for extended periods during interplanetary missions. Stress is a constellation of events, beginning with a stimulus (stressor) that precipitates a reaction in the biological system that subsequently activates physiologic subsystems in the body (stress responses). Stress has long been suspected of playing a role in the etiology of many diseases, and numerous studies have shown that stress can be immunosuppressive and hence may be detrimental to health. Stressful conditions of psychological or physical nature can activate and/or paralyze human innate or specific immunity, respectively.