Solitude and cortisol: Associations with state and trait affect in daily life

► We investigate whether being alone in daily life is related to cortisol levels. ► Young women had higher cortisol when alone. This association was not due to concurrent changes in affective state. ► Participants with high negative affectivity had higher cortisol levels when alone. Those with high positive affectivity had lower cortisol when alone. ► Neuroendocrine response to daily solitude may reflect vulnerability to depression.