Inclusion Criteria:

• 1. High school students between the age of 14-19 years
• 2. have typically insufficient sleep, defined by ≤ 7 hours per night on school days
• 3. BMI 5th-84th percentile for age and sex
• 4. habitually sedentary (\< 3 hours of regular physical activity per week)
• 5. Tanner stage 4 or 5, based on breast development for girls and testicular size for boys.

Exclusion Criteria:

• 1. Any medications that affect IR or sleep (e.g., metformin, stimulants, atypical antipsychotics, current use of oral steroids)
• 2. regular use of melatonin or other sleep aids
• 3. a prior diagnosis of a sleep disorder (e.g. insomnia, delayed sleep phase syndrome, obstructive sleep apnea)
• 4. Type 2 diabetes or prediabetes
• 5. IQ\<70 or severe mental illness that may impact sleep or ability to consent/assent (e.g., schizophrenia, psychotic episodes)
• 6. teens not enrolled in a traditional high school academic program (e.g., home school students)
• 7. schedules that would preclude participants from adhering to the sleep manipulation (e.g. night shift employment)
• 8. travel across more than two time zones in the 2 weeks prior to the study.