A Randomized Crossover Trial of Bright Light Therapy in Irritable Bowel Syndrome

April 1, 2026 updated by: Medical University of South Carolina
The purpose of this research study is to assess whether morning bright light therapy (BLT) using a wearable device called a Re-Timer could potentially improve Irritable Bowel Syndrome (IBS) symptoms and decrease intestinal permeability (leaky gut). Morning bright light therapy will be administrated through a safe-wearable glasses device called a Re-Timer. The Re-Timer glasses are lightweight and deliver blue-green light at 500nm, mimicking exposure to natural light.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The hypothesis of this study is that morning bright light therapy (BLT) using Re-Timer™ glasses in irritable bowel syndrome (IBS) patients with circadian misalignment (CM), will improve IBS symptom severity, improve circadian misalignment, decrease intestinal permeability and improve stool microbial diversity. Our overall objective is to assess the effects of morning bright light therapy on IBS symptom severity, circadian misalignment, intestinal permeability and intestinal microbiota. We propose to conduct a 6-week, single center, randomized, crossover pilot trial involving 30 subjects with active IBS symptoms (IBS-SSS >75), and circadian misalignment (CM) based on late chronotype (Munich Chronotype Questionnaire, Corrected Midpoint of Sleep > 4:00h). Subjects will be randomized to BLT or placebo with a 2-week washout between each condition. All subjects will have assessments at two timepoints: after 2 weeks of BLT, and after 2 weeks of placebo.

Study Type

Interventional

Enrollment (Actual)

5

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • South Carolina
      • Charleston, South Carolina, United States, 29425
        • Medical University of South Carolina

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria

  • 18-65 years old
  • Irritable Bowel Syndrome based on Rome IV diagnostic criteria
  • Mild to severe IBS symptom severity based on IBS-SSS greater than or equal to 75 17.
  • Late chronotype based on the Munich Chronotype Questionnaire (Corrected Midpoint of Sleep > 4:00h) 18 Exclusion Criteria
  • Subject that are pregnant or plan to become pregnant.
  • Night shift workers or people who have crossed more than 2 time zones in the previous 4 weeks.
  • Regular use of medications that affect intestinal permeability, and/or endogenous melatonin including metoclopramide, NSAIDs, beta blockers, antibiotics, psychotropic medications, hypnotics and exogenous melatonin products during 4 weeks prior to the study.
  • Any major organ disease - known renal impairment, diabetes, liver disease, or significant cardiac failure (NY classification stage III/IV), inflammatory bowel disease or celiac disease per chart review and/or medical history.
  • Diagnosis of narrow angle glaucoma or retinal disorders or demonstrated symptoms indicative of these diagnosis during the eligibility screening.
  • Moderate to severe depression (score ≥ 21 or any endorsement of suicidal intent on the Beck Depression Inventory) 19
  • Sleep apnea (score high risk in 2 or more categories of the Berlin Questionnaire) 20
  • Restless leg syndrome (score ≥ 15 on the IRLS Study Group Rating Scale) 21
  • Inability or unwillingness of subject to sign an informed consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Re-Timer Device (Bright Light Therapy)
Morning bright light therapy will be administrated through a safe wearable device called a Re-timer. The Re-Timer glasses are lightweight and deliver blue-green light at 500nm, mimicking exposure to natural light. The device emits light at a higher wavelength than the UV range and has a UV filter for added safety. Subjects will be asked to wear the glasses for one hour each morning per day for 7 days a week. They will wear the device for a total of 14 days to receive the full therapeutic effect. Additionally, subjects will be asked to complete the light therapy the first hour of being awake and remain indoors while using the device. Participants will be informed that they can wear the device freely throughout their home or work environment but should avoid activities that could potentially be harmful (i.e., driving, contact sports, operating heavy machinery).
Device: Re-Timer glasses
Morning bright light therapy (BLT) will be administered through a safe wearable glasses device called a Re-Timer, purchased from the manufacturer Re-Timer.
Placebo Comparator: Placebo device (non Bright Light Therapy)
Subjects will be asked to wear glasses that do not provide Bright Light Therapy for one hour each morning per day for 7 days a week as recommended by the manufacturer. They will wear the device for a total of 14 days to receive the full therapeutic effect. Additionally, subjects will be asked to complete the light therapy the first hour of being awake and remain indoors while using the device. Participants will be informed that they can wear the device freely throughout their home or work environment but should avoid activities that could potentially be harmful (i.e., driving, contact sports, operating heavy machinery).
Device: Placebo Device
Placebo glasses not providing Bright Light Therapy

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Aim 1a
Time Frame: 2 weeks of morning Bright Light Therapy (BLT)
In Aim 1a, we predict 2 weeks of morning BLT in IBS subjects with CM will improve IBS-symptom severity based on the IBS Severity Scoring Scale as compared to the control (wear the Re-Timer™ glasses without light therapy).
2 weeks of morning Bright Light Therapy (BLT)
Aim 1b
Time Frame: 2 weeks of morning Bright Light Therapy (BLT)
In Aim 1b, we predict 2 weeks of morning BLT will improve circadian misalignment as accessed by wrist actigraphy (interdaily stability, intradaily variability, and relative amplitude).
2 weeks of morning Bright Light Therapy (BLT)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Aim 2
Time Frame: 2 weeks of morning Bright Light Therapy (BLT)
Aim 2, we will evaluate the impact of BLT on intestinal barrier homeostasis in IBS as measured by 2a) intestinal permeability, urinary sucralose percent excretion after oral challenge and 2b) stool microbiota diversity using 16S ribosomal RNA sequencing. We predict that BLT will decrease intestinal permeability and improve stool microbiota diversity and structure.
2 weeks of morning Bright Light Therapy (BLT)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of South Carolina

Collaborators

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

  • Principal Investigator: Caitlin Green, Medical University of South Carolina

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 11, 2025

Primary Completion (Actual)

March 31, 2026

Study Completion (Actual)

March 31, 2026

Study Registration Dates

First Submitted

November 4, 2024

First Submitted That Met QC Criteria

November 4, 2024

First Posted (Actual)

November 6, 2024

Study Record Updates

Last Update Posted (Actual)

April 7, 2026

Last Update Submitted That Met QC Criteria

April 1, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Pro00138575
  • P30DK123704 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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