Metabolic HealthCOMETNCT05820490
ImpaCt Of Shiftwork on METabolic Flexibility and Skeletal Muscle Clocks
An observational study of Metabolic Health, run by AdventHealth Translational Research Institute at 1 site in United States.
Trial summary
The purpose of this study is to determine the impact of real-world shiftwork on metabolic flexibility. Read more about this study
- Who is it for?
- Ages 21 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Metabolic Health
- What is being tested?
- Whole Room Calorimeter, Mixed-Meal Tolerance Test (MMTT) and Core Body Temperature
- Type of treatment
- Surgery or procedure
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Jul 2023to 31 Jan 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: We will enroll normal weight and overweight, sedentary, but otherwise healthy adults employed in shiftwork.
Who may be able to join
- Age 21-45 yrs
- Employed as a healthcare worker in either dayshift (N=15) or nightshift work (N=30).
- Nightshift is defined as 12 months of consecutive nightshift work, who had 10 or more nightshifts per month (6 h between 10 PM and 8 AM, with no shift duration > 12 h).
- Dayshift is defined as 12 months of consecutive dayshift work, who had 10 or more dayshifts per month (6h between 8 AM and 10 PM, with no shift duration > 12 h).
- Weight Stable (+/- 3 kg over past 6 months)
- BMI between 18.5-29.9 kg/m2
Show all 9Show fewer
- Understands the procedures and agrees to participate by giving written informed consent
- Willing and able to comply with scheduled visits, laboratory tests, and other study procedures including
- Only low to moderate caffeine users (<500 mg/day, or up to approximately 5 cups [1 cup=8 ounces] of coffee/day.
Who cannot join
- Acute or chronic medical conditions or medication that would contraindicate participation in the research testing or could potentially affect metabolic function including, but not limited to:
- History or presence of cardiovascular disease (unstable angina, myocardial infarction or coronary revascularization within 6 months, presence of cardiac pacemaker, implanted cardiac defibrillator)
- Type 1 or Type 2 diabetes mellitus
- Obesity (BMI ≥ 30 kg/m2)
- Bleeding and clotting disorders
- Uncontrolled hypertension (BP >160 mmHg systolic or >100 mmHg diastolic)
Show all 35Show fewer
- Acute or chronic infections (such as TB, HIV, or Hepatitis)
- Renal insufficiency or nephritis (eGFR<60), nephritis, or chronic kidney disease
- Chronic obstructive pulmonary disease
- Thyroid dysfunction (suppressed TSH, elevated TSH <10 µIU/ml if symptomatic or elevated TSH >10 µIU/ml if asymptomatic)
- Liver disease (liver function tests > 2 x normal; including nonalcoholic steatohepatitis [NASH] and non-alcoholic fatty liver disease [NAFLD])
- Diagnosed or being treated for sleep disorders
- History of Cushing's disease or syndrome
- Pregnant or nursing females or females less than 6 months postpartum from the scheduled date of collection
- Anemia (hemoglobin <12 g/dl in men, <11 g/dl in women) during screening
- Participation in studies involving investigational drug(s) within 30 days prior to Screening
- Gastrointestinal disorders (including inflammatory bowel disease or malabsorption, swallowing disorders, suspected or known strictures, fistulas or physiological/mechanical GI obstruction, history of gastrointestinal surgery, Crohn's disease or diverticulitis)
- Past or present history of psychiatric disease, including major depressive illness or bipolar disorder, as well as claustrophobia since part of the protocol will involve being confined to a small room for whole-body indirect calorimetry
- Unwilling or unable to eat foods provided in study procedures
- Nickel allergy
- Lidocaine allergy
- Any malignancy not considered cured, except basal cell carcinoma and squamous cell carcinoma of the skin (a participant is considered cured if there has been no evidence of cancer recurrence in the previous 5 years)
- Use of antibiotics within 3 months of screening
- Illicit drug use (negative tests at screening)
- Regular smoking or regular nicotine use of any kind including chewing tobacco, snuff and vaping
- History of regular alcohol consumption exceeding 7 drinks/week for female participants or 14 drinks/week for male participants (1 drink = 5 ounces [150 mL] of wine or 12 ounces [360 mL] of beer or 1.5 ounces [45 mL] of hard liquor) within 6 months before screening.
- Excessive caffeine use (>500 mg/day, or exceeding 5 cups [1 cup= 8 ounces] of coffee/day)
- Blood donation (excluding plasma donations) of approximately 1 pint (500 mL) or more within 56 days prior to Screening (participants may not donate blood any time during the study, through the final study day)
- Presence of any condition that, in the opinion of the Investigator, compromises participant safety or data integrity or the participant's ability to complete study days.
- More than 1-day a week of intentional exercise
- Excluded medications include, but are not limited to:
- Any prescription medication or other drug that may influence metabolism (e.g. diet/weight-loss medication, psychiatric medications, corticosteroids, or other medications at the discretion of the PI and/or study team)
- Medications that strongly impact bleeding, clotting, bruising, or platelets (e.g. blood thinner prescription medications)
- Recent change to medication and/or dosing in the past 3 months
- Chronic use of aspirin or other non-steroidal anti-inflammatory drugs, including COX-2 inhibitors
Trial locations and contacts
1 site in 1 country.
United States1 site
AdventHealth Translational Research Institute
Orlando, Florida, 32804
About this study
The purpose of this study is to determine the impact of real-world shiftwork on metabolic flexibility.
- Conditions
- Metabolic Health
- Being tested
- Whole Room Calorimeter, Mixed-Meal Tolerance Test (MMTT), Core Body Temperature, Morningness-Eveningness Questionnaire, Muscle Biopsy
- Keywords
- metabolic flexibility, skeletal muscle circadian clock, fatty acid oxidation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Whole Room CalorimeterOther
The indirect calorimetry system allows your oxygen / carbon dioxide exchange to be measured, thereby showing the number of calories burned.
Mixed-Meal Tolerance Test (MMTT)Other
The MMTT is done to measure how much body handles a mixed meal.This test shake will raise blood sugar and cause the body to produce insulin.
Core Body TemperatureOther
Participants will be asked to swallow a core body temperature monitor prior to entering the whole room calorimeter. This monitor is used to record participants core body temperature.
Morningness-Eveningness QuestionnaireOther
Participants will fill out a questionnaire that asks about your preference for morning or evening.
Muscle BiopsyProcedure or surgery
Participants will have two skeletal muscle biopsies (one in the evening and one in the morning). This procedure is used to sample muscle cells from the right and left leg Vastus Lateralis (thigh) muscle.
Serial Blood SamplingOther
Participants will have blood sampled every hour for 24 hours to assess changes in circulating hormones.
| Study group | Role | What they receive |
|---|---|---|
| Dayshift workers | Not described Receives: Other: Whole Room Calorimeter; Other: Mixed-Meal Tolerance Test (MMTT); Other: Core Body Temperature; Other: Morningness-Eveningness Questionnaire; Procedure: Muscle Biopsy; Other: Serial Blood Sampling | |
| Nightshift workers | Not described Receives: Other: Whole Room Calorimeter; Other: Mixed-Meal Tolerance Test (MMTT); Other: Core Body Temperature; Other: Morningness-Eveningness Questionnaire; Procedure: Muscle Biopsy; Other: Serial Blood Sampling |
What is being measured
The primary outcome is the main question the study is designed to answer.
Metabolic flexibility, or substrate switching capacity, will differ between dayshift and nightshift workers.
Rates (change over time) of substrate oxidation will be assessed via whole-room indirect calorimetry during a 24h protocol that includes controlled meals and sleep.
Measured: 30 days, including a two night stay
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Apr 2023
- Study start28 Jul 2023
- Primary completion31 Jan 2026
- Study completion31 Jan 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Metabolic HealthStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Other
- Time perspective
- Cross-sectional
- Enrolment
- 40 participants (actual)
Sponsor and investigators
- Lead sponsor
- AdventHealth Translational Research Institute
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Melissa Erickson, PhD, Principal investigator, Study Principal Investigator
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05820490
- Sponsor's protocol ID
- 1993997
- Acronym
- COMET
- Status last verified
- Apr 2026
- First submitted
- 28 Feb 2023
- Last updated
- 15 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 15 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- ImpaCt Of Shiftwork on METabolic Flexibility and Skeletal Muscle Clocks
- ClinicalTrials.gov ID
- NCT05820490
- Acronym / sponsor ID
- COMET / 1993997
- Conditions
- Metabolic Health
- Keywords
- metabolic flexibility, skeletal muscle circadian clock, fatty acid oxidation
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 40 participants (actual)
- Lead sponsor
- AdventHealth Translational Research InstituteUniversity, hospital or other
- Study start
- 28 Jul 2023 (actual)
- Primary completion
- 31 Jan 2026 (actual)
- Study completion
- 31 Jan 2026 (actual)
- First posted
- 19 Apr 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to determine the impact of real-world shiftwork on metabolic flexibility.
Study design
- Observational model
- Other
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Dayshift workers | – | Other: Whole Room Calorimeter, Other: Mixed-Meal Tolerance Test (MMTT), Other: Core Body Temperature, Other: Morningness-Eveningness Questionnaire, Procedure: Muscle Biopsy, Other: Serial Blood Sampling |
| Nightshift workers | – | Other: Whole Room Calorimeter, Other: Mixed-Meal Tolerance Test (MMTT), Other: Core Body Temperature, Other: Morningness-Eveningness Questionnaire, Procedure: Muscle Biopsy, Other: Serial Blood Sampling |
Who may qualify
- Ages
- 21 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- We will enroll normal weight and overweight, sedentary, but otherwise healthy adults employed in shiftwork.
Key inclusion criteria (9 listed)
- Age 21-45 yrs
- Employed as a healthcare worker in either dayshift (N=15) or nightshift work (N=30).
- Nightshift is defined as 12 months of consecutive nightshift work, who had 10 or more nightshifts per month (6 h between 10 PM and 8 AM, with no shift duration > 12 h).
- Dayshift is defined as 12 months of consecutive dayshift work, who had 10 or more dayshifts per month (6h between 8 AM and 10 PM, with no shift duration > 12 h).
- Weight Stable (+/- 3 kg over past 6 months)
Key exclusion criteria (35 listed)
- Acute or chronic medical conditions or medication that would contraindicate participation in the research testing or could potentially affect metabolic function including, but not limited to:
- History or presence of cardiovascular disease (unstable angina, myocardial infarction or coronary revascularization within 6 months, presence of cardiac pacemaker, implanted cardiac defibrillator)
- Type 1 or Type 2 diabetes mellitus
- Obesity (BMI ≥ 30 kg/m2)
- Bleeding and clotting disorders
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Whole Room CalorimeterThe indirect calorimetry system allows your oxygen / carbon dioxide exchange to be measured, thereby showing the number of calories burned. | Other | Dayshift workers, Nightshift workers |
| Mixed-Meal Tolerance Test (MMTT)The MMTT is done to measure how much body handles a mixed meal.This test shake will raise blood sugar and cause the body to produce insulin. | Other | Dayshift workers, Nightshift workers |
| Core Body TemperatureParticipants will be asked to swallow a core body temperature monitor prior to entering the whole room calorimeter. This monitor is used to record participants core body temperature. | Other | Dayshift workers, Nightshift workers |
| Morningness-Eveningness QuestionnaireParticipants will fill out a questionnaire that asks about your preference for morning or evening. | Other | Dayshift workers, Nightshift workers |
| Muscle BiopsyParticipants will have two skeletal muscle biopsies (one in the evening and one in the morning). This procedure is used to sample muscle cells from the right and left leg Vastus Lateralis (thigh) muscle. | Procedure or surgery | Dayshift workers, Nightshift workers |
| Serial Blood SamplingParticipants will have blood sampled every hour for 24 hours to assess changes in circulating hormones. | Other | Dayshift workers, Nightshift workers |
Primary outcome
Metabolic flexibility, or substrate switching capacity, will differ between dayshift and nightshift workers.
Time frame: 30 days, including a two night stay
Rates (change over time) of substrate oxidation will be assessed via whole-room indirect calorimetry during a 24h protocol that includes controlled meals and sleep.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Apr 2026.
- AdventHealth Translational Research Institute websiteLink provided by the sponsor.
Related trials for Metabolic Health
Recruiting
Colon-delivered Riboflavin and Gut Microbiota Composition
Microbiome Dysbiosis, Gut Health
Recruiting
Metabolic Health, Bones and Nuts During Weight Loss in Adults
Weight Loss, Bone Density
Active, not recruiting
SweetSpot - The Effect of Non-nutritive Sweeteners on Health
Healthy Adult
Not yet recruitingPhase 2
Obesity Treatment With Phentermine-Topiramate ER in AYA Surviving Leukemia and Lymphoma
Acute Lymphoblastic Leukemia in Remission, Hodgkin Lymphoma in Remission
Not yet recruitingObservational study
Evaluating Metabolic Health in Individuals With Extreme Obesity
BMI>40
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Melissa Erickson, PhD principal investigator
Study Principal Investigator
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Metabolic Health, run by AdventHealth Translational Research Institute at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 35 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Metabolic flexibility, or substrate switching capacity, will differ between dayshift and nightshift workers. (time frame: 30 days, including a two night stay). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Apr 2026.