Inclusion Criteria:  14-17 years old; Participants and parents have sufficient knowledge of the English language; Participants are fully vaccinated for COVID-19  Exclusion Criteria:  personal history of a psychotic disorder, bipolar disorder, neurological disorder, psychopathology, sleep disorder (sleep apnea, restless legs syndrome, narcolepsy, insomnia), metabolic disorders, chronic medical conditions (e.g., cancer, diabetes, kidney disease, active asthma), or infectious illness; current illness, fever or symptoms of respiratory infection or allergy at the time of laboratory assessments; current use of prescribed mediations (except birth control pills); current use of melatonin or over-the-counter medications that can affect the sleep/wake cycle, daytime sleepiness, or suppress melatonin; physical handicap that interferes with the study (e.g., blind); mental retardation or other pervasive developmental disorder; symptoms of depressed mood based on a score of 16 or greater on the Center for Epidemiological Studies fro Depression (CES-D); suicidal ideation (past or current) travel beyond two time zones within a month of beginning the study; female participants who indicate symptoms of premenstrual dysphoric disorder (PMDD) unusual sleep lengths (means < 6 hours or > 10 hours); color blind as determined by the Ishihara color blindness test, or eye surgery to correct for lens curvature; positive test for illicit drugs or nicotine; positive test for alcohol at the beginning of the 7-day lab stay