Objectives: The present study assessed bidirectional associations between basic psychological needs and several subjective sleep variables across 2 semesters. Design: Participants completed an online survey twice (7 months apart) as part of a short-term longitudinal, correlational study. Participants: Participants were 154 (67.8% female) emerging adults (mean age = 20.02 years, SD = 1.71) from a liberal arts university on the east coast. Measurements: Survey assessed demographics, perceived fulfillment of basic psychological needs (autonomy, competence, and relatedness), and several sleep variables (week and weekend sleep duration, sleep disturbances, daytime dysfunction, and sleep quality; Pittsburgh Sleep Quality Index). Results: Data were analyzed using an autoregressive cross-lagged model, which controlled for level of study, diagnosis of mental illness, self-esteem, social desirability, sleeping medication, chronotype, conscientiousness, and extraversion. Results indicated significant unidirectional associations: perceived fulfillment of basic psychological needs predicted longer week sleep duration (beta = .243, P = .008) and better perceived sleep quality (beta = -.223, P = .008) 1 semester later, and 1 significant bidirectional association, perceived fulfillment of basic psychological needs, predicted lower daytime dysfunction, and in turn, lower daytime dysfunction predicted higher perceived fulfillment of basic psychological needs 1 semester later. Conclusions: Although many sleep interventions focus on environmental aspects of sleep, our findings highlight the importance of nurturing university students' psychological needs as a potential point of intervention for improving some sleep characteristics among emerging adults at university. (C) 2019 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.