Inclusion Criteria:  Healthy adolescents (any sex, gender, race, or ethnicity) aged 14-18 years, inclusive  Exclusion Criteria:  Obesity, because findings are meant to inform obesity-prevention efforts Use of a psychiatric medication or other drug with known effects on sleep, weight, or dietary behaviors. Intellectual disability (aka mental retardation) Symptoms of insomnia, obstructive sleep apnea or periodic limb movement disorder, which could mask the effects of the sleep manipulation. Work or other obligations that require bedtime later than 9:30 pm or waking prior to 10 am (earliest bedtime and latest rise time possible during sleep extension) during the final week of the study, or other scheduling obligations that preclude participation. Daily consumption of >1 coffee or "energy drink" or >2 caffeinated sodas. Currently diagnosed neurologic illness, history of seizures, or history of head injury resulting in loss of consciousness >1 min. Refusal to refrain from automobile driving during the sleep restriction period of the study. Symptoms of clinical depression, bipolar disorder, or psychosis.