This study is currently recruiting participants.
Studies suggest that eating late at night is linked with obesity; however, these studies do not account for differences in people s internal clocks. Researchers want to learn more.
To study how eating at different times, relative to a person s internal clock, affects metabolism.
Participants will have one overnight stay at Johns Hopkins University (JHU) and two 2-night stays at the National Institutes of Health (NIH).
One week before each overnight visit, participants will wear a device like a wristwatch to monitor their activities. They will keep diaries of their food and sleep. They will wear a sensor on their skin to monitor their blood sugar levels. Before the NIH visits, they will be asked to sleep at certain times.
At JHU, participants will swallow a pill-sized thermometer. They will sit still in dim lighting for up to 10 hours; saliva will be collected every 30 minutes. They will lie under a plastic dome to measure how much oxygen they use as they breathe.
At NIH, participants will stay in a special room that monitors the oxygen they inhale and the carbon dioxide they exhale. Lights will be turned on and off and meals will be delivered on a set schedule. They will have a thin tube placed in a vein in the arm for drawing blood.
The NIH stay will be repeated after 3 to 4 weeks. The sleep and meal schedules will be different at each visit.
INCLUSION CRITERIA:
Participants must meet all of the inclusion criteria to participate in this study.
-Normal-weight healthy (NWH) cohort:
--Healthy male and female adults, age 18-50
--BMI 18-24.9 kg/m^2
-Obesity-Prediabetes (OPD) cohort:
--Male and female adults, age 18-50
--BMI >=30 kg/m^2
--Prediabetes defined by a documented hemoglobin A1c 5.7-6.4% or fasting glucose from 100 to 125 mg/dL or 2-hour glucose from 140 to 199 mg/dL after 75-gram oral glucose tolerance test within the past 12 months
-All participants must be able to understand study procedures, to comply with them for the entire length of the study and be fully mobile.
EXCLUSION CRITERIA:
All candidates meeting any of the exclusion criteria at baseline will be excluded from study participation.
-Sleep disorder including insomnia, untreated moderate-severe sleep apnea, restless leg syndrome, or narcolepsy
-Night shift work
-Extreme delayed sleep phase defined as self-reported routine bedtime later than 1:00 AM or having mid-sleep on free days later than 5:00 AM on the Munich Chronotype Questionnaire (MCTQ) or DLMO later than 24:00
-Gastroesophageal reflux disease that affects ability to tolerate a dinner close to bedtime
-Active smoking (may interfere with metabolism and CRU activities)
-Current drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements.
-Diabetes (type 1 or 2) or on any diabetes medications besides metformin
-Evidence of metabolic or cardiovascular disease, or disease that may influence metabolism
-HbA1c point of care >=5.7% for NWH cohort; HbA1c point of care >=6.5% for OP cohort
-Point-of-care hemoglobin < 10 g/dL
-Self-reported kidney disease
-Any known history of an inherited metabolic disorder
-Pregnant or lactating female (pregnancy test will be required prior to metabolic visits)
-Peri-menopausal or post-menopausal female as determined by follicle stimulating hormone of > 30 mIU/mL or fewer than 3 menstrual periods in 6 months
-Professional or collegiate athlete
-Participants who have travelled across time zones must have adequate time to recover from jet lag prior to enrollment (i.e., at least 3 days per time zone). Travel across >1 time zone after enrollment in the study will not be permitted.
-Weight less than 40 kg or more than 180 kg
-Gastrointestinal disorders that can lead to obstruction of the digestive tract (i.e. diverticular disease, history of bowel obstruction, inflammatory bowel disease, motility disorder), if participant will be ingesting continuous body temperature monitoring pill
-History of any surgical procedures in the gastrointestinal tract, if participant will be ingesting continuous body temperature monitoring pill
-Swallowing disorders, if participant will be ingesting continuous body temperature monitoring pill
-Taking any prescription medication or other drug that may influence metabolism (e.g. diet/weight-loss medication, blood pressure medication, psychiatric medications, systemic corticosteroids, or other medications at the discretion of the PI and/or study team)
-Chronic use of sedative hypnotics, anxiolytics, opiates
-Use of medications that can affect circadian rhythm (beta blockers, melatonin)
-Presence of a cardiac pacemaker or other implanted electro-medical devices
-Those who have to undergo strong electromagnetic field during the period of use of the ingestible thermosensor (i.e. MRI)
-Weight loss or gain of >= 5% of total body weight over the preceding 3 months
-Currently participating in a weight loss program
-Prior bariatric surgery
-Volunteers with strict dietary concerns that cannot be accommodated by study staff
-History of significant intravenous access issues
-Non-English speaking individuals: The complexity of the instructions for various components of the study would make the study procedures difficult to follow in the setting of a language barrier.
-Other conditions or situations at the discretion of the PI