Fig. 1

Experimental design. a In-laboratory repeated measures counterbalanced design. From left to right, the degree of social separation participants wished to keep from approaching others was assessed using a real, in-person human approach task, followed by a computerized version, used during a functional magnetic resonance imaging (fMRI) scan. At the end of each session, participants performed a recorded interview with open-ended questions, which was subsequently rated by independent judges, blind to study goal or sleep manipulation. b Online phase study design. Participants were asked to complete daily sleep logs for two consecutive nights tracking their habitual variations in sleep time. Following each sleep survey, participants completed a next-day questionnaire assessing social behavior and loneliness