The present proposal aims at investigating how prolonged isolation and confinement affects the decision-making processes in humans. Available results on human cognitive performance in isolated and confined environments (ICE) reveal a very mixed picture (e.g., Kanas and Manzey, 2008; Van Baarsen et al., 2009; 2011; 2012). The general picture is even sketchier about the decision-making processes. Behavioral data at standard decision making tasks, salivary stress hormones, and sleep quality questionnaires will be longitudinally collected at 4 time points along one year in order to address how decision-making processes change during isolation and whether and how these changes are linked to the biological rhythms.