Experimental Manipulation of Sleep and Circadian Rhythms and the Role Played on Reward Function in Teens

Inclusion Criteria: * Typically enrolled in a traditional high-school with synchronous learning (in-person or online synchronous learning, but not cyber- or home-schooling) \[school closures during the COVID-19 pandemic are an exception to this\] * Physically and psychiatrically healthy * Provision of written informed consent and assent * Additional inclusion criterion for Experimental protocol: Meets operational definition of late sleep timing (\>10:50PM habitual bedtime) Exclusion Criteria: * History of alcohol, cannabis, or illicit drug use in the past month, or greater than monthly use in the past year * Significant or unstable acute or chronic medical conditions * Frequent headaches or migraines * History of seizures * Current serious psychiatric disorder (e.g., depressive disorder, bipolar disorder, eating disorder, psychotic disorder diagnosis, alcohol use disorder or substance use disorder) that would interfere with completion of study procedures * Current syndromal sleep disorders other than insomnia and delayed sleep phase disorder * MRI contraindications (i.e., absence of metal in the body, claustrophobia) * Medications that increase sensitivity to blue light/photosensitizing medications, including psychiatric neuroleptic drugs, psoralen drugs, antiarrhythmic drugs, etc. * Changes to psychotropic medication regimen in the 2 weeks prior to enrollment, and/or major changes to medications during the study protocol * If participants have an average bedtime that is l…