The overall goal is to examine the efficacy of a circadian intervention in people with overweight and obesity and habitual short sleep duration (HSSD). Participants will undergo a randomized controlled trial, with circadian intervention and control (healthy lifestyle) groups. The circadian intervention is designed to reduce nighttime light exposure and after-dinner snack food intake. Alternatively, the control group will receive basic health information (e.g., physical activity, goal setting, and nutrition when eating out).
Age: 18-45 years old; equal numbers of men and women
Body mass index (BMI): 25.0-34.9 kg/m2,
Sleep Habits: habitual self-reported average total sleep time (TST) <6.5 hours per night for prior 6 months
Clinically diagnosed sleep disorder or major psychiatric illness
Evidence of significant organ dysfunction or disease (e.g., diagnosed diabetes, cardiovascular disease, or kidney disease)
Use of prescription drugs or substances known to influence sleep or glucose metabolism
Shift-work: current or history of within last year
Parallel
Circadian Intervention
BehavioralThe circadian intervention group will receive counseling and instruction to reduce evening and nighttime light exposure, increase morning room light and sunlight exposure, and to finish all food consumption at least 4 hours before bedtime.
Insulin sensitivity change from baseline
Oral Glucose Tolerance Test (OGTT), Matsuda Index
Timing of central circadian clock change from baseline
Quantified as dim-light melatonin onset from salivary melatonin samples
Plasma ceramides change from baseline
Fasting plasma samples will be analyzed for plasma ceramides using targeted metabolomics
Average (per week) nightly total sleep time change from baseline
Analyzed by wrist-actigraphy
Average (per week) sleep satisfaction change from baseline
5 point likert scale on daily sleep log (1 = very good; 5 = very poor)
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