Circadian Timing, Information Processing and Energy Balance Study

The goal of this study is to determine how sleep and circadian rhythm alignment contribute to neurobehavioral and behavioral mechanisms of cardiometabolic risk. The investigators propose that circadian misalignment, which is more common among individuals with late sleep timing, leads to increased consumption of energy dense/prepared foods and to decreased insulin sensitivity. Short sleep duration and neurobehavioral measures (i.e. delay discounting) may moderate these associations, thus exacerbating cardiometabolic risk factors. There is evidence for a direct biological link between circadian misalignment and insulin resistance, and for a relationship that is mediated through changes in eating behaviors. Insulin resistance and increased caloric intake over time lead to increased BMI and body fat.

In this study, the investigators will conduct cross-sectional and longitudinal analyses to determine biological and behavioral mechanisms that link circadian alignment and sleep duration to changes in cardiometabolic risk over 1 year. This study will identify individual differences that predict risk for cardiometabolic disorders and suggest potential for sleep, circadian and neurobehavioral interventions to reduce cardiometabolic risk.

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.