Effects of a long-term isolated, confined and extreme environment in Antarctica on psychological well-being

True isolation is rare in everyday life but common in extreme environments such as Antarctic stations or long-duration space missions. Understanding the psychological impact of prolonged confinement is increasingly relevant. This study assessed emotional well-being during one-year overwintering missions at Concordia Station, a terrestrial space analogue characterized by extreme isolation and confinement. Thirty-six participants across three annual campaigns completed monthly self-assessments using ten Visual Analogue Scales (VAS), the Positive and Negative Affect Schedule (PANAS), and completed quarterly the Profile of Mood States (POMS) on a quarterly basis. Station medical doctors provided monthly external expert ratings using the same VAS for each crew member. Linear mixed-effects models were used for analysis. Self-reported well-being followed a seasonal pattern, with a marked decline during midwinter and partial recovery toward the mission’s end. PANAS Positive affect decreased, while POMS fatigue, confusion, and tension increased. VAS scores followed a sinusoidal trend, with happiness decreasing and homesickness peaking midwinter. The distinct psychological trajectories observed across crews, despite identical environmental conditions, strongly point to the influence of group-specific dynamics. Age and sex also moderated outcomes: older participants reported fewer negative emotions, while women reported greater mood variability. Expert ratings were generally more positive than self-reports, particularly in one overwintering campaign, highlighting the importance of multi-source assessment. This study reveals subtle but measurable psychological strain during long-term exposure to isolated, confined, and extreme (ICE) environment exposure, even in healthy individuals. The combined use of sensitive mood measures, multi-informant ratings, and advanced modelling techniques provides a comprehensive picture of adaptation in extreme environments. Findings have relevance for spaceflight, polar expeditions, and other isolated team settings. • Longitudinal assessment of psychological wellbeing during Antarctic overwintering, offering a multi-perspective view of adaptation in isolated, confined, and extreme (ICE) environments. • Unique comparison of three separate overwintering periods, highlighting the critical role of group composition, dynamics, and possibly leadership style in ICE missions. • Inclusion of both men and women with age-stratified analysis, showing that older individuals reported more stable emotional states, while women showed higher mood variability. • Empirical confirmation of an emotional low since midwinter followed by partial recovery by psychologically healthy individuals.