ImpaCt Of Shiftwork on METabolic Flexibility and Skeletal Muscle Clocks

NCT05820490 | Completed

• 1 other identifier: 1993997
• Study Type: observational
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to determine the impact of real-world shiftwork on metabolic flexibility.

Conditions

Metabolic Health

Keywords

metabolic flexibility; skeletal muscle circadian clock; fatty acid oxidation

Outcome Measures

Primary Outcomes (1)

• 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.

  30 days, including a two night stay

Study Arms (2)

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

Interventions

Whole Room Calorimeter OTHER

The indirect calorimetry system allows your oxygen / carbon dioxide exchange to be measured, thereby showing the number of calories burned.

Dayshift workers; Nightshift workers

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.

Dayshift workers; Nightshift workers

Core Body Temperature OTHER

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.

Dayshift workers; Nightshift workers

Morningness-Eveningness Questionnaire OTHER

Participants will fill out a questionnaire that asks about your preference for morning or evening.

Dayshift workers; Nightshift workers

Muscle Biopsy PROCEDURE

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.

Dayshift workers; Nightshift workers

Serial Blood Sampling OTHER

Participants will have blood sampled every hour for 24 hours to assess changes in circulating hormones.

Dayshift workers; Nightshift workers

Eligibility Criteria

• Age: 21 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Probability Sample

Study Population

We will enroll normal weight and overweight, sedentary, but otherwise healthy adults employed in shiftwork.

You may qualify if:

• 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
• 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.

You may not qualify if:

• 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)
• 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

Sponsors & Collaborators

• AdventHealth Translational Research Institute: lead

Study Sites (1)

AdventHealth Translational Research Institute

Orlando, Florida, 32804, United States

Location

Related Links

• AdventHealth Translational Research Institute website

Biospecimen

Retention: SAMPLES WITH DNA

We will sample muscle biopsies during the evening and morning time to examine diurnal shifts in skeletal muscle clock gene expression, which is a proxy of in vivo skeletal muscle circadian timing. We will also take serial blood draws every hour for 24 hours to assess changes in circulating hormones.

Study Officials

• Melissa Erickson, PhD

  Study Principal Investigator

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 28, 2023
• First Posted: April 19, 2023
• Study Start: July 28, 2023
• Primary Completion: January 31, 2026
• Study Completion: January 31, 2026
• Last Updated: April 15, 2026

Record last verified: 2026-04

Locations

US (1)