This week’s newest studies in red light therapy and photobiomodulation. See last week’s research here.
This Week in Red Light Therapy
This was a review-heavy week, with big pooled analyses on pain and two reviews that keep coming back to the same question: what’s the right dose?
- Study 1: A review of 105 studies found Class IV lasers reduced pain in every randomized knee, spine, shoulder, and wound trial it covered.
- Study 2: A review of PBM for brain conditions says human studies show gains in cognition, movement, and mood, with dosing still unsettled.
- Study 3: A review of 20+ years of research says red light’s muscle effects follow a sweet spot, and getting the dose right is the hard part.
- Study 4: Across 14 trials, more studies favored PBM, but the trials were too varied, and the numbers weren’t pooled, to pick a winner.
- Study 5: Only about 1 in 5 jaw-pain laser trials reported enough detail to repeat the treatment.
High-Intensity Lasers Reduced Pain Across 105 Studies
The study: Researchers searched PubMed, Google Scholar, and the Cochrane Database for trials of Class IV high-intensity laser therapy (HILT, which runs at roughly 100 times the power of low-level lasers) published from 2018 to April 2026, and pooled 105 studies with 2,710 treated patients and 2,925 controls.
What they found:
- No serious adverse events were reported.
- HILT reduced pain in every randomized trial of knee (27 trials), spine and neuromuscular (20), shoulder and arm (20), and wound (2) conditions, with more than 90% showing large effects.
- Pain stayed lower at follow-up, with standardized mean differences (a score where about 0.8 or higher counts as a large effect) of -0.98 at the end of treatment, -1.18 under 3 months, and -1.01 at 3 months or more.
- HILT beat low-level laser therapy for pain in 13 of 13 head-to-head studies.
What this means for you: This review covers clinic-grade lasers, so the results don’t apply directly to home devices. If you’re dealing with chronic pain in a knee, back, or shoulder, it’s a treatment worth asking a clinician about.
Review: Red Light Shows Promise for Thinking, Movement, and Mood in Brain Conditions
The study: Xiong, Su, Chen, and Verkhratsky wrote a review of how photobiomodulation affects disorders of the central nervous system, including neurodegenerative diseases, brain trauma, and psychiatric disorders.
What they found:
- PBM uses specific light wavelengths to activate cytochrome c oxidase (an enzyme in your cells’ energy-making mitochondria) and light-sensitive proteins, and it helps regulate brain cell activity.
- Human studies showed improvements in cognitive performance, motor symptoms, and emotional distress.
- Results depend on wavelength, dose, and frequency, plus differences in each person’s anatomy and physiology.
- The authors want a database of disease-specific settings and large trials to confirm long-term safety.
What this means for you: Researchers see PBM as a promising, low-side-effect option for brain health. This is a review rather than a new trial, and it doesn’t give a recommended dose.
Review: Muscle Recovery With Red Light Depends on Getting the Dose Right
The study: Ahmed, Zhang, Hamzah, and Artan reviewed more than two decades of animal and human research on how wavelength, light intensity, dose, pulse structure, and timing affect muscle regeneration.
What they found:
- Red and near-infrared light affects cytochrome c oxidase, which boosts ATP (your cells’ energy) and triggers controlled reactive oxygen species (ROS) signaling that supports muscle stem cell activation, new blood vessel growth, and anti-inflammatory responses.
- The effects follow a biphasic dose-response, meaning there’s a sweet spot with weaker results above or below it.
- Tissue differs optically between animals and humans, which helps explain why clinical results vary.
- The authors recommend standardized dosing, calibrated equipment, and pairing PBM with exercise-based rehab.
What this means for you: The biology looks plausible, but a dose that works in animals doesn’t carry over directly to people. If you use light for athletic recovery, the authors point toward combining it with exercise-based rehabilitation.
PBM and TENS Both May Ease Jaw Pain, but the Evidence Can’t Pick a Winner
The study: A PRISMA-guided, PROSPERO-registered systematic review compared photobiomodulation with TENS (a device that sends mild electrical pulses through your skin) in 14 clinical trials covering 620 patients with temporomandibular disorders (jaw joint and muscle problems).
What they found:
- More of the included studies reported numerically larger improvements in pain relief and maximum jaw opening with PBM than with TENS.
- Overall, both treatments may improve pain and jaw function.
- Twelve of the 14 studies were rated Level III, meaning limited reporting quality.
- The studies varied a lot in patients, protocols, and outcome measures, and the review didn’t pool the numbers, so it can’t say either treatment is superior.
What this means for you: If you have jaw pain, both options may help, but this review can’t say PBM beats TENS. The trials behind it were too inconsistent to settle that.
Only About 1 in 5 Jaw-Pain Laser Trials Reported Enough Detail to Repeat the Treatment
The study: Bharali, Hazarika, Deuri, and colleagues ran a scoping review (a broad map of the evidence) of 175 controlled trials (165 randomized) testing PBM for temporomandibular disorders. For the 167 trials with an accessible full report, they checked how completely each one described its laser settings.
What they found:
- Wavelength and number of sessions were reported in 159 of 167 trials (95%).
- Power density was reported in 20 of 167 (12%), and total delivered energy in 24 of 167 (14%).
- Only 31 of 167 trials (19%) reported every item in a minimum set needed to reproduce the treatment, and 45 (27%) were non-reproducible.
- Protocols differed substantially even within the same device families.
What this means for you: Most of these trials don’t give enough detail to rebuild the dose, so it’s hard to know which settings drive the results. The authors want a minimum reporting standard enforced at publication.
Sources
- Penberthy WT, Vorwaller CE. “The importance of power in photobiomodulation: a systematic review and meta-analysis of high-intensity laser therapy.” Frontiers in Integrative Neuroscience, 2026. PubMed
- Xiong W, Su Y, Chen H, Verkhratsky A. “Photobiomodulation: multifaceted therapeutic effects on disorders in the central nervous system.” Clinical Science, 2026. PubMed
- Ahmed R, Zhang KL, Hamzah R, Artan NS. “Photobiomodulation for skeletal muscle regeneration: mechanisms, dosimetry, and translational challenges.” Frontiers in Bioengineering and Biotechnology, 2026. PubMed
- José Alves A, et al. “Comparative efficacy of photobiomodulation therapy and transcutaneous electrical nerve stimulation for temporomandibular disorders: a CONSORT-based methodological appraisal.” Swiss Dental Journal, 2026. PubMed
- Bharali K, Hazarika K, Deuri N, et al. “Photobiomodulation for temporomandibular disorders: A scoping review of laser-parameter reporting in controlled trials.” Cranio, 2026. PubMed
