Clinical Research Directory

Inclusion Criteria: * Demonstrate habitual sleep onset time between 10:00 pm-3:00 am on actigraphy; * able to read and write in English; * BMI 25-39.9 (overweight, class one obesity, or class two obesity) Exclusion Criteria: * High risk or presence of sleep disorders (obstructive sleep apnea (OSA), restless legs syndrome, or insomnia) as assessed by the questionnaires and overnight OSA screening; * Diagnosed with diabetes or HbA1c\>7 at screening or taking medications known to affect glucose; * History of cognitive or neurological disorders; * Presence of major psychiatric disorders, current alcohol or substance abuse as determined by screening questionnaires or self-report; * Unstable or serious medical illness; * Overnight shift work or travel over 2 time zones in the past 2 months; * Use of hypnotic, stimulant or medications know to affect melatonin concentrations such as beta blockers, daily NSAIDs; * Current smoking; * Daily caffeine intake \>300 mg; * Pregnant or lactating; * Currently on a restrictive of special diet.