Optimization of Chrononutrition to Reduce the Risk of Disease in Shift Workers (SHIFT)

Optimization of Chrononutrition to Reduce the Risk of Disease in Shift Workers - The SHIFT Study

In this randomized controlled trial, the investigators will assess the health impacts of optimizing the timing of dietary consumption in nurses and nursing assistants who work night shifts, have a habitual eating window of 14 hours or more, and elevated weight. Participants will be randomized to one of three groups: (1) dietary monitoring, (2) dietary monitoring plus 10-hour daytime time-restricted eating (TRE), or (3) TRE with a low-glycemic snack during night shifts. The study includes a 2-week screening/baseline health assessment, with follow-up health assessments at 3-, 6- (primary outcome), and 12 months.

Study Overview

• Status: Recruiting
• Conditions: Obesity; Overweight; Time Restricted Eating; Night Shift Work
• Intervention / Treatment: Behavioral: Dietary Monitoring; Behavioral: Time-Restricted Eating (TRE); Behavioral: Time-Restricted Eating with a Low-Glycemic Snack (TRE-LGS)

Detailed Description

The purpose of this study is to assess if reducing the number of hours during which participants eat each day, and consolidating dietary intake to the daytime, (with or without a low glycemic snack during night shifts) will help decrease weight and abdominal fat, improve glucose (sugar) regulation, and improve other markers of metabolic and cardiovascular health (i.e. lipid levels, inflammation markers, etc.).

Circadian clocks ("circa" means approximately and "dian" means day) are daily rhythms in physiology and behavior (activity, sleep, eating pattern) that help our body to anticipate and adapt to predictable events in the environment. These rhythms are generated and maintained by biological clocks that are present in the brain and almost every organ of our body. Remarkably, even in the absence of any timing information from a device, our body can keep track of time and thereby help us go to sleep and eat at optimum times. However, our lifestyle and work schedules can lead us to eat, exercise, and sleep at times that the clocks in our body are not prepared for. When these abnormal daily patterns continue for several weeks or years, it can affect our health in many ways including increased body weight, poor sleep, and elevated risk for various chronic diseases. Time-restricted eating (TRE), which restricts all dietary intake to a personalized consistent daily eating window to support circadian rhythms, has been shown to improve cardiometabolic health. However, TRE has not yet been assessed in people who work night shifts.

In this study, the investigators are interested in evaluating the effects of modifying eating patterns on the health of nurses and nursing assistants who work night shifts. Participants will be randomized to (1) dietary monitoring alone, or in combination with, (2) personalized 10-hour TRE (TRE), or (3) personalized 10-hour TRE with a low-glycemic snack provided to consume during night shifts (TRE-LGS). The TRE group will only be allowed water, black coffee, and tea (without any additives such as cream, sweetener including artificial sweeteners), during night shifts. The TRE+LGS group will be provided a low glycemic snack during night shifts.

The study is a year-long including a 2-week screening/baseline assessment, a 6-month guided intervention, and a 6-month self-guided intervention. Health assessments will be taken at screening/baseline, 3 months, 6 months (primary outcome), and 1 year (follow-up). Assessments will include weight (in clinic and at home), blood pressure (in clinic and at home), dietary recall (ASA24), body mass index, blood tests (biomarkers of cardiometabolic health parameters), glycemic regulation (Continuous Glucose Monitors), body composition ( duel energy x-ray absorptiometry, DXA), dietary intake (logged on the myCircadianClock smartphone app), sleep and quality of life questionnaires, and activity, sleep, and wrist temperature (actigraphy watch).

• Study Type: Interventional
• Enrollment (Estimated): 180
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: UCSD Study Coordinator; Phone Number: 858-246-2342; Email: research@mycircadianclock.org
• Study Contact Backup: Name: Salk Clinical Researcher; Phone Number: 1077 858-453-4100; Email: research@mycircadianclock.org

Study Locations

• United States
  • California
    • La Jolla, California, United States, 92037
      • Recruiting
      • University of California San Diego Altman Clinical and Translational Research Institute
      • Contact: UCSD Study Coordinator; Phone Number: 858-246-2342; Email: research@mycircadianclock.org
      • Contact: Salk Clinical Researcher; Phone Number: 1077 858-453-4100; Email: research@mycircadianclock.org
      • Sub-Investigator: Pam Taub, MD
      • Principal Investigator: Emily Manoogian, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age: 18-70 years
• BMI ≥ 25 kg/m2 (or ≥ 23 kg/m2 for Asian adults)
• Own a smartphone (Apple iOS or Android OS)
• Baseline eating window ≥ 14 h/day
• Night shift nurses and nursing assistants who are working a 12-hour night shift at least 3 days/week.
• Have been doing night shift work for at least 3 months.
• Patients on cardiovascular medications (HMG CoA reductase inhibitors (statins), metformin, lipid-modifying drugs (including over-the-counter drugs such as red yeast rice and fish oil), anti-hypertensive, drugs), are allowed
• If patients have Type 2 Diabetes, they will be included in the study if A1c is less than 9 and they are not on insulin.

Exclusion Criteria:

• Insufficient dietary logging on the mCC app is defined as less than 7 of 14 days of baseline of dietary logging with a minimum of 2 items a day, at least 5 hours apart.
• Type 1 Diabetes or Insulin-dependent Type 2 Diabetes.
• Use of sulfonylurea or insulin within the last 3 months (due to unknown safety with TRE)
• Use of medications that are known to cause weight loss such as SGLT2 inhibitors and GLP1 receptor agonists)
• BMI > 50 kg/m2
• Change in medications that could impact study outcomes within the past 3 months
• Change in weight of >4kg in the past 3 months
• Women who are pregnant, breastfeeding, or are trying to become pregnant during the study period. If a participant becomes pregnant during the study, they will be excluded from continuing the study.
• Systolic BP greater than 160 mmHg and/or diastolic BP greater than 110 mmHg at rest
• Fasting LDL cholesterol greater than 250 mg/dL
• Fasting triglycerides greater than 500g/dL
• Active tobacco abuse or illicit drug use or history of treatment for alcohol abuse in the past 5 years.
• Frequent (more than 4) travel involving a time zone change of more than 3 hours over the 1-year study period
• Prolonged leave from work (a continuous month or longer) during the study
• Active treatment for inflammatory and/or rheumatologic disease
• History of a major adverse cardiovascular event within the past year (acute coronary syndrome, percutaneous coronary intervention, coronary artery bypass graft surgery, hospitalization for congestive heart failure, stroke/transient ischemic attack)
• Uncontrolled arrhythmia (i.e. rate-controlled atrial fibrillation/atrial flutter are acceptable)
• History of thyroid disease requiring dose titration of thyroid replacement medication(s) within the past 3 months (hypothyroidism on a stable dose of thyroid replacement therapy is allowed).
• History of adrenal disease in the past 5 years
• History of malignancy undergoing active treatment, except non-melanoma skin cancer, in the past 5 years
• History of an eating disorder in the past 5 years
• History of cirrhosis in the past 5 years
• History of stage 4 or 5 chronic kidney disease or dialysis in the past 5 years
• History of HIV/AIDs
• Currently enrolled in weight-loss or weight-management program
• History of surgical intervention for weight management within the past 2 years, or longer if deemed unsafe following review by medical investigators
• Uncontrolled psychiatric disorder including prior hospitalization

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Dietary Monitoring; Log all dietary intake and continue habitual eating patterns.	Behavioral: Dietary Monitoring; Participants in the group will receive standard advice for a healthy lifestyle, log all food and beverage intake on the myCircadianClock app, and continue their habitual eating patterns.
Experimental: Time-Restricted Eating (TRE); Dietary Monitoring and adherence to a personalized consistent 10-hour time-restricted eating window	Behavioral: Time-Restricted Eating (TRE); Participants in the group will receive standard advice for a healthy lifestyle, log all food and beverage intake on the myCircadianClock app, and adhere to a personalized consistent 10-hour time-restricted eating window.
Experimental: Time-Restricted Eating with Low-Glycemic Snack (TRE-LGS); Dietary Monitoring and adherence to a modified personalized consistent 10-hour time-restricted eating window a low-glycemic snack provided by the research team to consume during night shifts.	Behavioral: Time-Restricted Eating with a Low-Glycemic Snack (TRE-LGS); Participants in the group will receive standard advice for a healthy lifestyle, log all food and beverage intake on the myCircadianClock app, and adhere to a personalized consistent 10-hour time-restricted eating window. On nights that participants work night shifts, they will consume a low-glycemic snack provided by the research team.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Body Fat Mass (kg)	Total Body Fat Mass (kg) assessed by DXA	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight (kg) in clinic	Body weight (kg) measured in clinic while participants are wearing a gown that has been weighed.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Body Mass Index	Body Mass Index (BMI) (kg/m2)	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
HbA1c (%)	Hemoglobin A1c (%) from fasted blood draw	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Intra-Daily Glycemic Variability: CONGA (A.U.)	Continuous Overall Net Glycemic Action (CONGA) assessed via continuous glucose monitor	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Inter-Daily Glycemic Variability: MODD (mg/dL)	Mean of Daily Differences (MODD) assessed via continuous glucose monitor	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Glycemic Variability: MAGE (mg/dL)	Mean Amplitude of Glycemic Excursions (MAGE) assessed by continuous glucose monitor	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Mean Glucose (mg/dL)	Mean Glucose assessed by continuous glucose monitor	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Fasting Glucose (mg/dL)	Blood glucose assessed from a fasted blood draw	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Fasting Insulin (uIU/mL)	Blood insulin assessed from a fasted blood draw	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Blood Pressure (mmHg)	Systolic and Diastolic Blood Pressure taken in clinic.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Direct LDL Cholesterol (mg/dL)	Direct LDL cholesterol from fasted blood draw	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Non-HDL Cholesterol (mg/dL)	Non-HDL cholesterol from fasted blood draw	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Blood Pressure (mmHg)_at home measurements	Systolic and Diastolic blood pressure taken at home. Measurements are taken twice (one measurement on a work day and one on an off day) during the 2 week assessment periods. Each day measurements will be taken 3 times throughout the day. Averages for work days and off days will be reported for each time point. Averages at each time point will be reported.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Lean Mass (g)	Whole body lean mass (g) assessed by DXA scan	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Percent Body Fat (%)	Whole body percent Body Fat (%) assessed by DXA scan	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Visceral Adipose Tissue Mass (g)	Whole body Visceral Adipose Tissue Mass (g) assessed by DXA scan	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Body Weight (kg) at home	Participants will weigh themselves every 2 weeks at home on study provided scales in the morning.	From enrollment to the end of the intervention at 1 year.
Blood Glucose Time in Range (%)	Time in range (%) from continuous glucose monitor.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Glycemic Management Indicator (%)	Glycemic Management Indicator (GMI, %), an estimate of A1c, from continuous glucose monitor.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Triglycerides (mg/dL)	Triglycerides (mg/dL) from fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Total Cholesterol (mg/dL)	Total cholesterol (mg/dL) from fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
HDL-cholesterol (mg/dL)	HDL-cholesterol (mg/dL) from fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
hs-CRP (mg/dL)	hs-CRP (mg/dL) from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
LDL Particle number (nmol/L)	LDL Particle number (nmol/L) assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Apo A (mg/dL)	Apo A (mg/dL) assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Apo B (mg/dL)	Apo B (mg/dL) assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Apo A/B ratio	Apo A/B ratio assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Very Low Density Lipoprotein (VLDL) Size (nm)	VLDL size (nm) assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
HDL Particle number (umol/L)	HDL Particle number (umol/L) assessed by NMR lipoprotein profiles from a fasted blood draw.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Quality of Life Assessment	Short-Form 36 (SF-36) Survey. Scores range from 0-100 (an average of all questions which each have a 0-100 scale), with 100 indicating better physical and emotional health.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Sleep Duration	Average total daily sleep duration assessed by actigraphy watch	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Pittsburgh Sleep Quality Index	Pittsburgh Sleep Quality Index (PSQI). Each item is scored on a 0-3 scale with a total score of 0-21. A lower score indicates better sleep.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Epworth Sleepiness Scale	Epworth Sleepiness Scale (ESS). Scored from 0-24. A lower score indicates less sleepiness.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)
Chronotype	Munich Chronotype Questionnaire (MCTQ) Shiftwork estimates an individuals chronotype.	Baseline, 3 month, 6 month (primary), and 12 month (follow-up)

Collaborators and Investigators

• Sponsor: Salk Institute for Biological Studies
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); University of San Diego
• Investigators: Principal Investigator: Emily Manoogian, Ph.D., Salk Institute for Biological Studies

Study record dates

Study Major Dates

• Study Start (Actual): June 2, 2025
• Primary Completion (Estimated): August 31, 2028
• Study Completion (Estimated): March 3, 2029

Study Registration Dates

• First Submitted: March 12, 2025
• First Submitted That Met QC Criteria: March 18, 2025
• First Posted (Actual): March 24, 2025

Study Record Updates

• Last Update Posted (Actual): December 17, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Nurses; Time-Restricted Eating; Night Shift work; Nursing Assistants
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Pathological Conditions, Signs and Symptoms; Behavior; Nutritional and Metabolic Diseases; Signs and Symptoms; Feeding Behavior; Fasting; Overweight; Obesity; Intermittent Fasting
• Other Study ID Numbers: 24-0002; 1R01DK139356-01 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: We will report deidentified individual participant data for outcomes that are reported in scientific publications (text, tables, figures, and appendices).
• IPD Sharing Time Frame: Data will be available within 1 month of publication with no set end date (minimum of 5 years).
• IPD Sharing Access Criteria: Data will be available to anyone who wants to access it through a data depository that will be disclosed at the time of publication.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No