As the duration of manned spaceflight becomes longer and as crews become more heterogeneous, psychological and interpersonal factors will be more important in affecting the safety of crew and flight mission. In space environment there are four types of stressors: physical, physiological, psychological and interpersonal. Psychological issues include "Asthenia", alteration in time sense, transcendent experiences, sleep problem, career motivation, psychosomatic symptoms and psychiatric issues. Interpersonal issues include interpersonal tension, interpersonal relationships decreased cohesiveness and deprivation, displacement [correction of dispiacement] of anger to outside personnel over time.