Sleep is an important factor for overall health. This study will see how different light exposure patterns and food intake impact a person's metabolism (how the body breaks down food) when sleeping is reduced.
Participants will attend 6 to 8 in-person visits to the study clinic, including three overnight stays. People will complete surveys and medical tests. The study will last about 4 to 6 months.
Age: 18-35 years old; equal numbers of men and women
Body Mass Index (BMI): 18.5-24.9 kg/m2
Sleep Habits: habitual self-reported average total sleep time (TST) 7-9 hours per night for prior 6 months
Clinically diagnosed sleep disorder or apnea hypopnea index (AHI) ≥5
Evidence of significant organ system dysfunction or disease (e.g., heart disease, diabetes)
Fasting plasma glucose ≥100 mg/dL
Major psychiatric illness (e.g., major depressive disorder)
Crossover
Central Clock Misalignment
BehavioralLight exposure will be dimmed during the first 4 hours of scheduled wakefulness, with bright light exposure during the nighttime hours of extended wakefulness.
Peripheral Misalignment
BehavioralMost daily calories will be given later in the day to shift eating patterns toward the nighttime hours.
Insulin Sensitivity
Insulin sensitivity will be measured by intravenous glucose tolerance tests.
Internal Circadian Misalignment (Uridine and Isobutyryl-L-carnitine)
Phase angle between DLMO and acrophase of uridine and isobutyryl-L-carnitine during constant routine.
Timing of DLMO and DLMOff
The phase angle between dim-light melatonin offset (DLMOff) scheduled waketime using hourly saliva samples collected during a constant routine.
Hunger and Satiety Visual Analog Scales
Self-reported ratings of hunger, satiety, and prospective food intake will be quantified by 100mm visual analog scales ranging from 0 to 100. For each scale, 0 represents low hunger, satiety, or prospective food intake, with 100 representing the highest hunger, satiety, or prospective food intake.
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