 This study will be a randomized, crossover, outpatient sleep restriction SR study with 2 phases of 6 weeks each, with a 6 week wash-out period between the phases. Sleep duration in each phase will be the participants regular bed- and wake times during the habitual sleep HS phase and HS minus 1.5 hours in the SR phase. During the HS phase, participants will be asked to follow a fixed bedtime routine based on their screening sleep schedule. During the SR phase, participants will be asked to keep their habitual wake time constant but delay their bedtime to achieve a reduction of 1.5 hours in total sleep time. 