The Metabolic and Circadian Effects of Shift Work

Study Overview
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Brief Summary
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In an exploratory observational pilot study, the investigators will focus on the effects of short-term circadian misalignment induced by shift work on multidimensional measurements including glucose excursion, metabolic health, circadian rhythms (measured in vitro and in vivo), sleep/wake cycles and ambient light, eating and activity patterns, well-being and attention.

Official Title
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The Metabolic and Circadian Effects of Shift Work - An Observational Study

Conditions
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Shift Work Schedule

Intervention / Treatment
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* Other: Exposure to shift work


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women Age 20-50 years Working ≥ 80% full-time equivalent over the previous month and during the study Working night shifts (i.e. shifts that comprise working hours between 23h and 06h) in rotation with day shifts (i.e. shifts that comprise working hours between 06h and 20h) Planned to work at least 3 consecutive night shifts during the study preceded by at least a day off or day shift Planned to work at least 3 consecutive day shifts during the study Confident use of a smartphone compatible with the study application (iOS, Android) and able to regularly take pictures of consumed food/drinks Able to give a fully informed consent and follow the study procedures Exclusion Criteria: Planned or current pregnancy during the study Menopausal women Major illness or hospitalization over the previous month Carries a pacemaker, pump or other medical device that can be disabled by a magnet Major mental illness Trip to a different time zone (≥ 2-hour time difference) over the previous month or planned during the study Enrolled in an interventional clinical trial (potentially interfering with the main outcomes) over the previous month or planned during the study

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Shift workers<br>Measurements repeated during a series of day shifts and during a series of night shifts | Other: Exposure to shift work<br>* Detailed questionnaire adapted from the Standard Shiftwork Index, measured at inclusion<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in glucose excursion | As measured by Continuous Glucose Monitoring | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in fasting glucose | As measured by clinical chemistry (mmol/L) | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in weight | Body weight (Kg) | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in waist circumference | Waist circumference (cm) assessed with a measuring tape | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in lipid profile | Total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol measured by clinical chemistry (mmol/L) | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in blood hormonal profile | Insulin (mIU/L), thyroid-stimulating hormone (mIU/L), cortisol (nmol/L) measured by clinical chemistry | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in eating duration | Time from the first to last caloric intake over a 24-hour period | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in nutrient intake | Total calorie and macronutrient intake over a 24-hour period | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in systolic and diastolic blood pressure | As measured by blood pressure arm cuff | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in heart rate variability | As measured by wearable sensor | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in physical activity | As measured by actigraphy and the International Physical Activity Questionnaire | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in sleep/wake cycles | As measured by actigraphy | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in sleep quality | As measured by the Pittsburgh Sleep Quality Index (PSQI), score ranges from 0 to 21 points, 0 indicating no difficulty and 21 severe difficulties | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in attention and sleepiness | As measured by the Sustained Attention to Response Test | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in well-being | As measured by the World Health Organization-5 questionnaire (WHO-5), score ranges from 0 to 25, 0 indicating worst possible and 25 best possible | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months | 
| Difference in mental health outcomes | As measured by the Patient Health Questionnaire-9 (PHQ-9), score ranges from 0 to 27, 0 indicating no depression and 27 severe depression | Between a series of day shifts and a series night shifts, separated by an interval from 10 days to 3 months |