Home Sleep and Circadian Phase: Mediators of Diabetes Risk

Inclusion Criteria: 1. Ages 21-50 years 2. BMI \<40 kg/m2. 3. No major illness. 4. No history of psychiatric, endocrine, cardiac or sleep disorders, 5. Premenopausal, non-pregnant women. 6. Those with dyslipidemia and hypertension will be included if these conditions are controlled by a stable treatment, such as lipid-lowering or antihypertensive medications (except beta blockers). Exclusion criteria include: 1. Persons with diabetes. 2. Persons with diagnosed sleep disorders or apnea-hypopnea index\>15. 3. History of cardiovascular event or disease (excluding controlled hypertension). 4. Major psychiatric disorder or other major illness. 5. Persons taking medications, including but not limited to antidepressants and hypnotics (but excluding lipid-lowering drugs and anti-hypertensive medications as mentioned above). 6. Persons regularly taking medication that affects melatonin such as beta blockers and exogenous melatonin. 7. Anyone who tests positive for common drugs of abuse. 8. People with color blindness. 9. People who have had Lasik eye surgery. 10. People who work night shifts. 11. Participants who travel across multiple time zones will be studied only after they have remained in the Central Time Zone (or Indiana) for one month prior to the study.