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The goal of this study is to uncover sleep and circadian mechanisms contributing to adverse metabolic health. The protocol is a 21 day (7 outpatient days, 14 inpatient days) mechanistic randomized-crossover study designed to identify the impact of chronic sleep restriction and circadian timing, independently and in combination on energy metabolism and identify the independent and combined effects on glucose tolerance.
Full description
Nearly half of all Americans are obese and/or have been diagnosed with diabetes, accounting for over 327 billion dollars in health care costs in the United States each year. Increasing evidence suggests that chronic short-sleep durations contribute to these diseases, but the specific mechanisms as to how short-sleep durations results in weight gain and diabetes are debated.
Reports of weight gain due to sleep restriction do not comply with the energy balance hypothesis, which would predict that with an increased amount of wakefulness and an associated increase in energy expenditure, there would be a negative shift in energy balance and resulting weight loss over time. Restricting sleep in the laboratory, however, pushes participants towards a positive energy balance via increased daily energy intake when access to food is ad libitum.
The goals of this study are to uncover the impact of chronic sleep restriction, circadian timing, and their combination on energy intake patterns, determine the influence of chronic sleep restriction on food choice when there is equal opportunity to eat at all circadian times, and discover the impact of chronic sleep restriction, circadian timing, and their combination, on glucose tolerance.
After instrumentation, participants will be given an 8h sleep opportunity at habitual timing (determined via actigraphy) and will be awakened at habitual wake time in dim-lighting for a baseline "day". During baseline, participants will be given three energy-balanced meals. After baseline, participants' sleep/wake schedule will be advanced by 4h daily for the next 12 calendar days with the participants having access to ad libitum food. Prior to arriving to the laboratory, participants will be randomized to either sleep restriction first (equivalent to obtaining 5.5h of sleep per 24h; n=10) or control conditions first (equivalent to 8h sleep per 24h; n=10); crossover to the other condition will occur on day 8 of the protocol. Because the protocol requires participants to live on a 20h-day, during the control condition participants will experience 13.33-hour wake episodes followed by 6.67-hour sleep opportunities, while during the sleep restriction condition they will experience 15.33-hour wake episodes followed by sleep episodes of 4.67 hours long, in the range typically experienced by individuals who habitually restrict their sleep. Providing ad libitum food during this time will be accomplished, as done previously, by providing participants a breakfast, lunch and dinner at ~130-150% more calories than their baseline day and switching out sets of snacks between meals - "morning" (between breakfast and lunch), "afternoon" (between lunch and dinner), and after-dinner (between dinner and sleep). Snacks will be of a variety of healthy (i.e., grapes, low-fat yogurts, whole-grain crackers, nuts, etc.) and unhealthy (i.e., ice cream, cookies, chips, sodas, etc.) options and participants will not need to ask or record what they eat.
Enrollment
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Volunteers
Inclusion criteria
Exclusion criteria
Dietary restrictions
Participants must not have dietary restrictions that could systematically bias their macronutrient intake. The following will exclude participants from enrolling in the study based on their diet:
Body Composition
A body mass index (BMI) of 18.5< [BMI] < 25 kg/m2 and a waist circumference <94/80cm.
Psychiatric/psychological suitability
Each participant will undergo a structured interview (Mini International Neuropsychiatric Interview) with a qualified OHSU physician. This physician will supervise the administration and scoring of a Beck Depression Inventory II (BDI-II) questionnaire for each potential participant. The following will exclude individuals from participating based on their psychiatric or psychological evaluation:
Drug/alcohol use
Volunteers must be drug-free (including caffeine, nicotine, alcohol and herbal medications) for the entire duration of the outpatient and in-laboratory study period, with no history of drug or alcohol dependency. All participants must be:
Medication/drug use
Volunteers must not be taking any prescribed medications or over the counter medications, with an exception for birth control.
Prior shift work
For stability of endogenous circadian rhythmicity, volunteers must have no history of the following 1 year prior to the study:
Chronobiologic and sleep disorders
Diseases of the Cardiovascular System
Metabolic Syndrome
Following American Heart Association cutoffs, participants who have, in addition to abdominal fat (obese exclusion criteria), two or more of these factors will be excluded from the study:
Pre-Diabetes/Diabetes
For participants who have a fasting blood glucose level of ≥ 100 mg/dL the investigators will measure hemoglobin A1c to exclude for diabetes (HbA1c>5.7%).
Hypertension
An upper cut off of 140/90 mmHg during an office blood pressure measure will be used as an exclusion criterion. After 5 minutes of rest in a seated position, blood pressure will be measured 3 times, taken 1 minute apart. The average will be used to confirm eligibility criteria. Current or history of beta blocker use will also be exclusionary.
Disorders of the Respiratory System
Disorders of the Kidney and Urinary Tract
Infectious Diseases
Disorders of the Gastrointestinal System
Disorders of the Immune System, Connective Tissue and Joints
Disorders of the Hematopoietic System
Neoplastic Diseases
Endocrine and Metabolic Diseases
Neurologic Disorders
Subjects must not be currently participating in another research study that would influence their safe participation in our study. Subjects must not be participating in a research study in which they do the following:
Primary purpose
Allocation
Interventional model
Masking
20 participants in 2 patient groups
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Central trial contact
Andrew McHill, PhD
Data sourced from clinicaltrials.gov
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