Light & photobiomodulation · graded by use, two uses
Photobiomodulation (musculoskeletal)
Chronic neck pain and chronic tendinopathy pain, low-level laser therapy.
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How this letter has changedLatest: October 2026 · Corrected.
The B rested on one meta-analysis A study that pools the numbers from several trials into one combined estimate. of neck pain and a review described as covering skin, which it does not. A PubMed search added Yap and Lim (J Back Musculoskelet Rehabil, 2025; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 40437920), tendinopathy, positive; Tomazoni et al. (J Physiother, 2020; PMID 32680739), low back pain, no worthwhile effect against sham A fake version of a procedure or device used as the comparison, so participants cannot tell which one they received.; and Glazov et al. (Acupunct Med, 2016; PMID 27207675), low back pain, subgroups only. Neck and tendinopathy pain hold B; low back pain is C.PMID 40437920 PMID 32680739 PMID 27207675
The record carried a not-replicated flag while its B rested on a meta-analysis of randomized trials in neck pain (Chow et al., Lancet, 2009; PMID 19913903). The flag describes a single trial nobody has repeated; a meta-analysis of independent randomized trials is replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. by definition, and what caps this letter at B is the endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score., not the absence of a second trial. Flag removed, letter unchanged. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 19913903
The Energy Lounger was listed under pulsed electromagnetic field devices. It is a red and near-infrared light lounger, so it now sits under photobiomodulation. It carries no grade of its own. The modality grade rests on targeted low-level laser trials, and one randomized trial of whole-body light (Forsey et al., Lasers Med Sci 2023; PMID 37099210) found no effect on exercise performance.PMID 37099210
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Photobiomodulation uses low-level laser light on a painful area. Pooled trials from separate teams found it eased chronic neck pain and long-lasting tendon pain. These results rest on how people rated their own pain. For low back pain, the results were mixed. One large review found no worthwhile effect against a fake treatment, and another found benefit only in some smaller groups of patients.
The B belongs to one of the two uses graded on this record. The other one carries its own letter.
As studied, and the trials
Chow et al. (Lancet, 2009; PMID 19913903) and Yap and Lim (J Back Musculoskelet Rehabil, 2025; PMID 40437920): pain relief in pooled randomized trials at two body sites, from independent groups. Self-reported pain caps the letter at B.
As studied, and the trials
Tomazoni et al. (J Physiother, 2020; PMID 32680739) found no worthwhile effect against sham; Glazov et al. (Acupunct Med, 2016; PMID 27207675) found benefit only in subgroups. Mixed: C.
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A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Neck pain and tendinopathy pain (self-report).
Why this gradeThe reasoning, and what the grade does not cover.
Grade B on self-reported neck pain and tendinopathy pain. Pooled randomized trials found low-level laser therapy reduced chronic neck pain (Chow et al., 2009; PMID 19913903) and tendinopathy pain (Yap and Lim, 2025; PMID 40437920).
WHY NOT Aself-reported pain caps the grade.
WHAT THIS GRADE DOES NOT COVERnonspecific low back pain, where the evidence is mixed and graded C (Tomazoni et al., 2020; PMID 32680739; Glazov et al., 2016; PMID 27207675); knee osteoarthritis, graded on the Red Light / Near-Infrared protocol; skin; and oral mucositis, graded separately.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
Each use, with its trials
This record carries a separate letter for each thing it has been measured on. The headline grade is the best of them, and it does not transfer to the others.
Chow et al. (Lancet, 2009; PMID 19913903) and Yap and Lim (J Back Musculoskelet Rehabil, 2025; PMID 40437920): pain relief in pooled randomized trials at two body sites, from independent groups. Self-reported pain caps the letter at B.
Tomazoni et al. (J Physiother, 2020; PMID 32680739) found no worthwhile effect against sham; Glazov et al. (Acupunct Med, 2016; PMID 27207675) found benefit only in subgroups. Mixed: C.
The evidence, in fullFive papers, each linked to its PubMed record.
Chow et al. (Lancet, 2009; PMID 19913903): 16 randomized trials, 820 patients, placebo or active controls; in chronic neck pain, pain fell by about 20 mm on a 100 mm scale, lasting up to 22 weeks. Yap and Lim (Journal of Back and Musculoskeletal Rehabilitation, 2025; PMID 40437920): 15 randomized trials, short-term pain relief in chronic tendinopathy. Tomazoni et al. (Journal of Physiotherapy, 2020; PMID 32680739): 12 randomized trials, 1,046 people with nonspecific low back pain, mostly low risk of bias; the effect against sham was too small to matter. Glazov et al. (Acupuncture in Medicine, 2016; PMID 27207675): benefit only in subgroups. Pereira et al. (Journal of Lasers in Medical Sciences, 2025; PMID 41789279): a systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. of 8 trials of low-level and high-intensity laser for orthopedic pain, without pooling; it is not a deciding citation.
VAS pain scores and range of motion at the treated joint at baseline and every 4 weeks. Device parameters (wavelength, power density, treatment area, session duration) at every session: dose is the primary determinant of outcome and underdosing is the most common failure mode. For tendinopathy, expect 8-12 weeks before meaningful structural improvement.
Evidence notes: meta-analysis
Endpoint graded: Neck pain and tendinopathy pain (self-report) (self_report)
Last reviewed: October 2026
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
Primary evidenceFive papers, each linked to its PubMed record.
Chow et al. (Lancet, 2009; PMID 19913903): 16 randomized trials, 820 patients, placebo or active controls; in chronic neck pain, pain fell by about 20 mm on a 100 mm scale, lasting up to 22 weeks. Yap and Lim (Journal of Back and Musculoskeletal Rehabilitation, 2025; PMID 40437920): 15 randomized trials, short-term pain relief in chronic tendinopathy. Tomazoni et al. (Journal of Physiotherapy, 2020; PMID 32680739): 12 randomized trials, 1,046 people with nonspecific low back pain, mostly low risk of bias; the effect against sham was too small to matter. Glazov et al. (Acupuncture in Medicine, 2016; PMID 27207675): benefit only in subgroups. Pereira et al. (Journal of Lasers in Medical Sciences, 2025; PMID 41789279): a systematic review of 8 trials of low-level and high-intensity laser for orthopedic pain, without pooling; it is not a deciding citation.
Products carry no letter. The letter belongs to the therapy as the trials studied it, and no trial tested these products unless the entry says so. Listed alphabetically; payment does not affect order.
Full-body red and near-infrared light lounger (the company also sells the F100 targeted unit and a blanket). It is a light-therapy device, not PEMF. The Photobiomodulation (musculoskeletal) grade rests on trials of targeted low-level laser at the painful site; a whole-body lounger delivers light at a lower power density over a larger area, which those trials did not test. One randomized crossover A trial design in which each participant receives both the treatment and the comparison, one after the other, and serves as their own control. trial of whole-body photobiomodulation (Forsey et al., Lasers Med Sci 2023; PMID 37099210, n=48 healthy adults) found no effect on anaerobic cycling performance or most physiological measures, with a modest next-day heart rate variability signal.
Whole-body format at lower power density than the targeted devices in the graded trials. Company claims of weight loss and anti-aging are not supported by any cited trial.
independently verified irradiance. 660nm + 850nm dual wavelength. Most cited in clinical contexts. Third-party tested output vs. advertised output match.
Whole-body PBM at clinical irradiance, the only way to dose the entire body simultaneously. Used in professional sports and clinical research. Clinic-only.
Whole-body PBM bed; re-filed from transcranial to skin/MSK PBM.
Five-wavelength panel (630, 660, 810, 830, 850nm). High irradiance per dollar. Independently verified output. Strong community of clinical users.
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How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("low-level laser"[tiab] OR "low level laser"[tiab] OR photobiomodulation[tiab]) AND (musculoskeletal[tiab] OR "neck pain"[tiab] OR "back pain"[tiab] OR osteoarthritis[tiab] OR tendinopathy[tiab] OR "shoulder pain"[tiab]) AND meta-analysis[pt]Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →