Polar expeditions include treks and stays at summer camps or year-round research stations. People on such expeditions generally undergo psychological changes resulting from exposure to long periods of isolation and confinement, and the extreme physical environment. Symptoms include disturbed sleep, impaired cognitive ability, negative affect, and interpersonal tension and conflict. Seasonal occurrence of these symptoms suggests the existence of three overlapping syndromes: the winter-over syndrome, the polar T3 syndrome, and subsyndromal seasonal affective disorder. About 5% of people on expeditions meet DSM-IV or ICD criteria for psychiatric disorders. However, they also experience positive or so-called salutogenic outcomes resulting from successfully coping with stress and enhanced self-sufficiency, improved health, and personal growth. Prevention of pathogenic psychological outcomes is best accomplished by psychological and psychiatric screening procedures to select out unsuitable candidates, and by providing access to psychological support, including telephone counselling. Promotion of salutogenic experiences is best accomplished by screening for suitable personality traits, and training participants in individual coping strategies, group interaction, and team leadership.