Photobiomodulation, Heart Rate Variability, and Acute Stress

NCT07475858 | Not Yet Recruiting

• 1 other identifier: 2026P000281
• Study Type: interventional
• Target: 40
• Locations: 0 countries
• Sites: N/A

Brief Summary

Photobiomodulation (PBM) is a form of light therapy that uses red or near-infrared light to influence biological processes. In prior studies, PBM has been shown to improve various physiological functions, including tissue repair, inflammation, and cognitive performance. However, little is known about its impact on autonomic nervous system regulation. Thus, the goal of this study is to evaluate the effects of PBM on vagal activity, as measured by heart rate variability (HRV), in healthy adults undergoing experimental stress.

Conditions

Stress

Keywords

Photobiomodulation; Heart rate variability; Vagus nerve; Stress

Outcome Measures

Primary Outcomes (1)

• Change in HRV, as measured by RMSSD

  Root mean square of successive differences (RMSSD) is a commonly used time-domain measure of HRV. It is commonly used to assess autonomic regulation, with higher RMSSD indicating greater parasympathetic activity and vagal tone. In this study, RMSSD will be calculated for every 5-minute segments of HRV data from baseline to post-phase. The area under the curve (AUC) will be computed to assess changes in RMSSD values with respect to baseline. This approach will allow for a comprehensive evaluation of changes in parasympathetic activity, in both magnitude and variability over time under different experimental conditions. Paired t-tests will then be used to compare AUCs between PBM and sham interventions, separately for before and after stress induction.

  50 minutes

Secondary Outcomes (3)

• Change in electrodermal activity (EDA)

  50 minutes

• Change in blood pressure (BP)

  50 minutes

• Change in state anxiety

  50 minutes

Study Arms (4)

Real PBM before stress induction

ACTIVE COMPARATOR

After a 5-minute baseline measurement, participants will receive 20 minutes of real PBM. They will then complete the 15-minute MAST protocol (stress induction) and be monitored for additional 10 minutes to assess recovery from stress.

Device: Vielight Vagus

Sham PBM before stress induction

SHAM COMPARATOR

After a 5-minute baseline measurement, participants will receive 20 minutes of sham PBM. They will then complete the 15-minute MAST protocol (stress induction) and be monitored for additional 10 minutes to assess recovery from stress.

Other: Sham Vielight Vagus

Real PBM after stress induction

ACTIVE COMPARATOR

After a 5-minute baseline measurement, participants will undergo the 15-minute MAST protocol (stress induction), followed by 20 minutes of real PBM and 10 minutes of post-intervention period.

Device: Vielight Vagus

Sham PBM after stress induction

SHAM COMPARATOR

After a 5-minute baseline measurement, participants will undergo the 15-minute MAST protocol (stress induction), followed by 20 minutes of sham PBM and 10 minutes of post-intervention period.

Other: Sham Vielight Vagus

Interventions

Vielight Vagus DEVICE

In this study, PBM will be administered using a transcutaneous cervical plus intranasal PBM device (Vielight Vagus, Ontario, Canada). The transcutaneous component of the device is designed to be placed bilaterally over the lateral aspect of the neck and delivers an irradiance of 810nm at 50mW/cm2, while the intranasal component is designed to be inserted into the nasal cavity and provides an irradiance of 810nm at 25mW/cm2. The pulse frequency will be set to 100 Hz and 50% duty cycle.

Real PBM after stress induction; Real PBM before stress induction

Sham Vielight Vagus OTHER

For sham intervention, the same PBM device will be placed on the participants in the same manner, but without emitting light to ensure blinding of the intervention.

Sham PBM after stress induction; Sham PBM before stress induction

Eligibility Criteria

• Age: 18 Years - 64 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy adults, aged 18-64 years
• Ability to read and understand English
• Willing to comply with the study procedures and attend all scheduled sessions

You may not qualify if:

• Taking medications that could significantly influence autonomic function
• Presence or history of any serious cardiovascular, inflammatory, and pain conditions as well as neurological disorders or other conditions that affect the central nervous system
• Pregnant

Sponsors & Collaborators

• Brigham and Women's Hospital: lead
• Vielight Inc.: collaborator

Study Officials

• Peter Wayne

  Brigham and Women's Hospital

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Peter Wayne, PhD

CONTACT

617-732-6271; pwyane@bwh.harvard.edu

EunMee Yang, PhD

CONTACT

617-582-9291; eyang13@bwh.harvard.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Model Details: This study will employ a within-subject, counterbalanced design to assess the effects of PBM on HRV. All participants will complete four testing visits. Each visit will involve the use of the MAST protocol to induce acute autonomic stress response under different conditions of PBM administration. The four conditions will be: 1) Real PBM before MAST; 2) Sham PBM before MAST; 3) Real PBM after MAST; and 4) Sham PBM after MAST. Participants will be randomly assigned to a counterbalanced order of these four conditions to control for order effects, and the visits will be spaced at least one week apart to minimize carryover effects between conditions.

Study Record Dates

• First Submitted: March 13, 2026
• First Posted: March 17, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): May 31, 2027
• Study Completion (Estimated): August 31, 2027
• Last Updated: March 17, 2026

Record last verified: 2026-02