Time-restricted Eating and Circadian Health in Night Shift Workers

Effect of a Time-restricted Eating Protocol on Glucose Homeostasis, Markers of Circadian System, Appetite Control, and Oxidative Stress Parameters in Night Shift Workers

The goal of this clinical trial is to learn about the effect of time-restricted eating (TRE) to 10 hours per day on glucose homeostasis, markers of the circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress status in night shift workers. The main questions it aims to answer are: 1) How does a time-restricted eating protocol affect glucose homeostasis in shift workers? and 2) How does a time-restricted eating protocol affect markers of the circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress status in shift workers? Participants will be asked to follow a TRE protocol on which they must restrict their eating to a self-selected time window of 10 hours a day, with mandatory fasting time between 24:00-06:00h. for 8 weeks. Researchers will compare the intervention with an additional period of 8 weeks, in which the participants will follow their usual diet without any time restriction, to see if the intervention improves glucose regulation appetite and markers of circadian system, homeostatic and hedonic regulation of appetite, and inflammation/oxidative stress.

This is a randomized, crossover, controlled, within-subject study. After recruitment, participants will be randomized to one of two conditions: i) Time-restricted eating (TRE), with an eating window of 10 hours per day but without any other diet modification (e.g., types of food or amount of energy consumed). Each participant can freely choose the starting time of their eating window. If a participant need to make modifications to the start time of their eating window, he/she may do so only once during the TRE period, and the research team must be informed. After a washout period of at least 30 days, participants will undergo ii) Regular eating (REG), during which the participants must maintain their usual eating pattern (i.e., usual eating window), without making any dietary or lifestyle changes. Each condition will have a duration of 8 weeks. Randomization will be done using computer-generated random numbers.

Inclusion Criteria:

Adults (range 18 - 60 yrs.) Men and women Performing as a healthcare worker Being a shift-worker for at least 6 months in the current schedule Working in rotating shiftwork, including at least one night shift Reporting no work-related performance difficulties

Exclusion Criteria:

• Current and chronic neurological disorders
• Pathologies related to abnormal adrenal activity
• Liver or kidney disease
• Uncontrolled hypertension, dyslipidemia, and thyroid disease
• Insulin resistance and T2D
• BMI ≥40 kg/m2
• Use of medications known to alter body composition, such as insulin sensitizers, glucocorticoids, or anti-depressants
• Autoimmune diseases with acute symptoms; recent surgery of any kind (in the last 3 months);
• Acute, chronic inflammation (usCRP >10 mg/L)
• Following any dietary restriction (special diet) in the previous three months
• Having a short sleep (habitual sleep duration of less than 6h per day)
• History of bariatric surgery
• Depression (Beck Depression Inventory) or sleep disorders (Pittsburgh Sleep Questionnaire)
• Night-eating syndrome (Night Eating Questionnaire)
• Intense exercise level (>3 days/week of high-intensity exercise)
• Having traveled across time zones (at any time during the last month) and planning travel during the study
• Pregnant or intend to become pregnant, and
• Lactating women