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

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
5

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Keaveny (Katy) Donovan
  • Phone Number: 843-792-7974
  • Email: donova@musc.edu

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Medical University of South Carolina

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 11, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 31, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 4, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 4, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 6, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 7, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 1, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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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