Many teenagers get too little and late timed sleep. High body weight and diabetes are increasing in teenagers as well. This study plans to learn more about whether improving sleep habits can help improve how the body regulates blood sugar and energy use in teenagers who have higher body weight. To answer this question, the investigators plan to enroll teenagers who get <7 hours of sleep on school nights and measure changes in blood sugars and energy use after two weeks of typical sleep (sleeping on their normal school schedule) and two weeks of a sleep intervention that includes spending longer time in bed at night, melatonin, and morning light.

Inclusion Criteria:

1. High school students between 14-19 years
2. Overweight/obesity (BMI >85% for age and sex)
3. Have habitually insufficient sleep, defined as ≤ 7 hours per night on school days
4. Habitually inactive (≤ 3 h of physical activity reported per week)
5. Tanner stage 4 or 5, based on breast development for girls and testicular size for boys.

Exclusion Criteria:

1. Reported diagnosis of sleep disorder (e.g., insomnia, obstructive sleep apnea)
2. Medical comorbidities that impact sleep or insulin sensitivity (e.g., diabetes [based on history or screening HbA1c])
3. Regular use of medications affecting sleep or insulin sensitivity (e.g., stimulants, sleep aids, systemic steroids, insulin sensitizers, GLP-1 agonists)
4. IQ<70 or severe mental illness that may impact sleep or study participation (e.g., schizophrenia), eating disorder, or active suicidal ideation
5. Schedules that would preclude participants from adhering to the sleep schedules (e.g., night-shift employment)

Data obtained through this study may be provided to qualified researchers with academic interests. Data shared will be coded, with no PHI included. Approval of the request and execution of all applicable agreements (i.e. a material transfer agreement) are prerequisites to the sharing of data with the requesting party.

Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.

Access to study IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA). For more information or to submit a request, please contact clinicalresearchsupportcenter@ucdenver.edu.