Photobiomodulation research library
A plain English guide to the clinical trials and reviews on red and near-infrared light, topic by topic. We include the studies that found no benefit, say which device each one used, and link every summary to its PubMed record.
Quick answer
Photobiomodulation (PBM) is the scientific name for red light therapy: low-power red and near-infrared light from a laser or LEDs, used to change how cells behave. It does not burn, tan or use ultraviolet light.
The research is real but uneven. The strongest evidence is for some long-term pain and tissue problems, such as back and neck pain, and for oral mucositis, a painful mouth side effect of cancer treatment. For most other conditions the evidence is mixed or early. Many trials are small, results vary with the device and dose, and some well-run trials found no difference from a sham (dummy) device.
Looking for a short answer by condition? Read does red light therapy work? This library goes deeper, with the individual studies.
Before you start
"Red light therapy" covers very different devices and doses. A result from one type of device does not automatically apply to another, so every summary below says what was used.
A focused beam held over one area, such as a painful joint or the lower back. Most pain trials used lasers, some of them higher-power lasers. Our THOR laser treatment is this type.
Arrays of light-emitting diodes that cover a wider area at lower intensity. Our guide to laser vs LED photobiomodulation explains the difference.
A bed lined with LEDs, such as NovoTHOR, that treats most of the body in one session. Very few published trials have used one.
Helmets, headbands or lasers aimed at the head to deliver near-infrared light to the brain. Almost all brain, mood and sleep trials used these, not whole-body beds.
People often feel better in trials whatever they receive. A sham-controlled trial compares real light with an identical device that gives no light, so it shows whether the light itself made the difference. We say when a trial had no sham.
A systematic review gathers every trial on a question and, in a meta-analysis, pools the results. One review usually tells you more than one small trial, although it is only as good as the trials it includes.
Some studies are funded or co-written by device makers, and some do not say. We note a maker's involvement where we know about it. These summaries come from THOR Photomedicine digests, so read about this library too.
Approved and research-only uses
The THOR devices we use have four approved uses in the UK:
Long-term tendon problems such as tennis elbow or Achilles pain. Our first set of studies did not include tendon research; it will be added in a later update.
Long-term pain in the joints. See joint pain and rheumatoid arthritis below.
See back and neck pain below.
Painful mouth sores caused by chemotherapy or radiotherapy. NICE guidance (IPG615) says evidence on the efficacy of low-level laser therapy for oral mucositis is adequate in quality and quantity, with no major safety concerns. It is usually given within cancer care, so ask your oncology team.
Everything else is research only. For every other condition in this library, including autoimmune conditions, dementia, depression, anxiety, sleep problems, skin conditions and hair loss, red light therapy is not an approved use. We report the research so you can see what has been studied. These are not approved uses of THOR devices in the UK, and we make no treatment claims for them.
The library
Each topic gives a plain English summary of what the studies in our library found, then a few key studies we have checked against their PubMed records. The coloured label on each study card shows what it found.
Topic 1 · Approved UK use
UK guidance first: the NICE guideline on low back pain and sciatica (NG59) recommends exercise and advises against several passive treatments, including ultrasound, TENS and acupuncture. Its recommendations do not mention laser therapy either way.
What our library holds: 25 studies on long-term pain, mostly low back pain (15) and neck pain (7), plus single studies on shoulder and jaw muscle pain. Eight are systematic reviews (one looked at ultrasound and shock wave therapy rather than light) and 17 are clinical trials. Almost all used lasers over the painful area. Pooled reviews found modest short-term pain relief compared with sham, mainly at higher doses, with less effect on disability and little evidence beyond a few months. Several trials found no extra benefit when light was added to an exercise programme.
Laser reduced pain more than sham in the short term, but only in trials using higher doses, in people whose pain had lasted under about two and a half years, and in trials that did not use an acupuncture approach. The authors rated the evidence moderate quality.
Pain scores after treatment were lower with laser than with placebo. There was no measurable effect on disability or on how far people could move their spine.
Both groups had less pain, disability and pain-related worry after Pilates. Adding light therapy to the lower back gave no extra benefit, and neither group improved its balance.
For long-term neck pain, moderate-quality evidence from two trials (109 people) favoured laser over placebo for pain, function and quality of life into the medium term. For neck pain from tight, tender muscles the trials conflicted. Ten of the 17 trials were at high risk of bias.
In five trials of muscular neck pain, laser lowered pain scores a little more than placebo, but the gain fell short of what patients usually notice as a real difference. The authors called the evidence inconclusive.
Also in the library: a 2024 review of 20 trials of high-intensity laser for neck pain found less pain when it was added to exercise, with low-certainty evidence (de la Barra Ortiz et al), and an 18-person trial in which a single laser session changed an inflammation marker in the blood but not pain (Tomazoni et al, 2021).
Read more in our guide to red light therapy for back pain, or see how we use targeted laser therapy in London.
Topic 2 · Chronic joint pain is an approved UK use
Chronic joint pain is one of the approved uses. Rheumatoid arthritis (RA) is different: it is an autoimmune disease that needs specialist care and medicines that slow the disease. No light therapy treats the disease itself, and you should never change RA medicines without your rheumatology team.
What our library holds: 9 papers on RA in the autoimmune digest: 3 meta-analyses, a review of physiotherapy guidelines, and 5 papers reporting 4 randomised trials. All used lasers on the hands or wrists. The results are mostly negative or mixed. Placebo-controlled hand trials found little or no difference from sham, and the most thorough recent review concluded that infrared laser may not be superior to sham.
Low-quality evidence suggested infrared laser may be no better than sham for pain, morning stiffness, grip strength, function or inflammation. Evidence on red laser and laser acupuncture was too uncertain to support or rule out a benefit.
Laser did not reduce pain compared with placebo. It did improve grip strength and shorten morning stiffness, although results varied a lot between studies.
Laser gave pain relief and better function straight after treatment, but there was no clear improvement in pain at three months or in morning stiffness.
There were few differences in grip strength, stiffness, tenderness, joint temperature, movement or pain, within or between the groups. The authors concluded the laser was ineffective at the settings used.
Most patients (72%) reported less pain, but equally in the treated and sham-treated hands. Other measures did not change. The authors put the pain relief down to a strong placebo effect.
Also in the library: an 82-person placebo-controlled trial of laser on RA hands that found no difference on the main measures (Meireles et al, 2010). Osteoarthritis and other long-term joint pain will be covered in a later update.
Read our guide to red light therapy for joint pain.
Topic 3 · Not an approved UK use
Fibromyalgia is not an approved use of THOR devices in the UK, and we make no treatment claims for it. Our fibromyalgia page summarises 20 papers covering 14 clinical trials and 4 reviews: in small sham-controlled trials, light therapy reduced pain for some people in the short term, but other trials found no difference, and adding it to exercise mostly gave no extra benefit. Reviews rate the evidence low to moderate quality, or lower.
See every study on our page about red light therapy for fibromyalgia.
Topic 4 · Research only
Research only. Thyroiditis, multiple sclerosis, lupus, Sjögren's syndrome, psoriasis, alopecia areata, ankylosing spondylitis and oral lichen planus are not approved uses of THOR devices in the UK, and we make no treatment claims for them. Keep taking any prescribed medicine and follow your specialist's advice.
What our library holds: 48 papers on autoimmune conditions other than RA. Half (24) are on oral lichen planus, a long-term inflammatory condition inside the mouth that is treated by dentists and oral medicine specialists; those studies used dental lasers inside the mouth. The rest are small groups: thyroiditis (4, all from one research team in Brazil), multiple sclerosis (7, including animal research), lupus (3), and single studies on Sjögren's syndrome, ankylosing spondylitis and pemphigus, plus a few we could not yet classify from the scans. Across the whole autoimmune digest, about a third of the papers are reviews and most of the rest are small trials. Results range from encouraging to clearly negative, and none is strong enough to change how these conditions are treated.
Nine months after thyroid tablets were stopped, the laser group needed a much lower dose of levothyroxine than the placebo group, and had lower levels of one thyroid antibody.
A small trial, and all four thyroid papers come from the same research team. A follow-up six years later reported no safety concerns (Höfling et al, 2018). Never stop thyroid medicine without your doctor.
The studies reported changes in markers of inflammation and cell damage, and some improvements in movement, sensation and thinking. No side effects were reported. The authors say more research is needed before it could be used as a treatment.
Much of this evidence comes from animal models. A separate 2024 meta-analysis pooled just three animal studies (Ahmed).
Neither group had any improvement in dry mouth symptoms or saliva flow, and there were no differences between the groups.
Pain and severity scores were no different with light therapy than with comparison treatments, including steroid gels. The authors suggest it may be an option when steroids do not work or cannot be used.
Oral lichen planus is a mouth condition treated by dentists and oral medicine specialists, not at our clinic.
With the same stretching programme, the laser group had less pain and better function than the placebo group at the end of treatment. Eight weeks later only the pain difference remained.
Also in the library: a lupus trial in which laser acupuncture, added to diet and Pilates, improved blood fat levels in women with obesity (Ismail et al, 2023). It measured cholesterol, not lupus symptoms.
Topic 5 · Research only
Research only, and a different device. These trials used transcranial devices that shine near-infrared light on the head, such as helmets, headbands or a laser on the forehead. They did not use whole-body beds, and the results cannot be applied to NovoTHOR. Dementia, mild cognitive impairment, depression, anxiety, sleep problems and concussion are not approved uses of THOR devices in the UK, and we make no treatment claims for them. If you are worried about your memory, mood or sleep, speak to your GP.
What our library holds: 70 papers: memory and thinking in healthy adults (19), dementia and Alzheimer's disease (16), depression (8), mild cognitive impairment (4), sleep (3), opioid craving (3), anxiety (2), and single studies on bipolar disorder, concussion and Parkinson's disease, plus 12 we could not yet classify from the scans. Nearly all are small clinical studies, many of them pilots or single-session experiments that measured brain activity or test scores rather than everyday symptoms. Most compared real light with a sham device. The results are interesting but early, and the largest depression trial here found no benefit.
Depression scores fell no more with real light than with sham. One author works for LiteCure, a laser device company. The authors think the dose was too low and describe this as a threshold below which the treatment does not work. An earlier pilot from the same group (ELATED-2) had reported encouraging results in about 20 people (Cassano et al, 2018).
Depression improved equally with the real and sham headbands. Sleep quality scores improved more with the real headband, and the difference lasted to week 12.
There was no difference between the groups in sleep efficiency, dream sleep or waking time. The real-light group did better on a short memory test.
After one session of light to the forehead, people in the real-light group did better on a visual memory test, while the sham group did not. This was a laboratory test, not a measure of daily life.
After real treatment, people did better on memory and learning tests and reported better sleep and fewer concussion, pain and PTSD symptoms. No improvement followed the sham treatment.
Very small, so it needs repeating in a larger trial.
Also in the library: a 30-person insomnia trial in which three sessions of light to the front of the head improved sleep quality scores more than sham (Mehdizadeh et al, 2025), and an early pilot of 10 people with depression and anxiety that had no separate control group (Schiffer et al, 2009).
Topic 6 · Research only
Research only. Skin conditions and hair loss, including psoriasis and alopecia areata, are not approved uses of THOR devices in the UK, and we make no treatment claims for them.
What our library holds: two reviews, both from the autoimmune digest: one on LED light for psoriasis and one on treatments for severe alopecia areata (patchy hair loss) in children. Eczema, acne and other skin topics are not yet covered in the library.
Only five studies met the criteria. The authors gave blue LED light a grade B recommendation, and red light, near-infrared plus red light, and LED ultraviolet light only a weaker grade C.
Light and laser therapy had an average response rate of about half, similar to topical immunotherapy, with no serious side effects reported. The studies compared treatments side by side rather than against a sham device.
Read more about red light therapy for skin conditions and red light therapy for hair growth.
Claims to be wary of
Safety
Most trials in this library reported few or no side effects, and several reported none at all, although not every trial recorded side effects carefully. Eye protection is standard, and people who take medicines that make the skin sensitive to light, or who have cancer, epilepsy or a light-sensitive condition, should get advice before treatment. Read our full guide: is red light therapy safe?
Sources and method
The studies come from research digests published by THOR Photomedicine, the company that makes the NovoTHOR bed and THOR laser we use. Because a manufacturer chose the studies, we check each one on PubMed, include trials that found no benefit, and write every summary ourselves from the published record. The digests themselves are THOR Photomedicine copyright and are not reproduced here.
Our first set of studies (152 from three digests on chronic pain, autoimmune conditions, and cognition and mood) was added on 15 October 2026. We will add new topics as more research is added. This library is for information only and is not medical advice. Speak to your GP or specialist about any health condition.
Questions
Photobiomodulation, or PBM, is the scientific name for red light therapy. It uses low-power red and near-infrared light from lasers or LEDs to change how cells behave, without burning, tanning or ultraviolet light. Researchers think the light is absorbed by mitochondria, the energy-producing parts of cells.
Partly. There are many published trials, and the strongest evidence is for some long-term pain, such as back and neck pain, and for oral mucositis, a painful side effect of cancer treatment. For many other uses the trials are small, early or mixed, and some found no benefit over a sham device.
No, but it is often oversold. Controlled trials show real effects for some uses, and NICE says the evidence for low-level laser therapy for oral mucositis is adequate. Claims that it cures disease, burns fat or detoxes the body are not supported by the studies in this library, and several trials found no difference from a sham device.
Some are. Device makers fund or co-author part of the research, including the whole-body NovoTHOR fibromyalgia trial. Many trials come from universities and hospitals, but funding is not always clear from the published summary. We note a maker's involvement where we know about it and give more weight to sham-controlled trials and reviews.
Very few so far. The main one is a triple-blind trial of the NovoTHOR bed in 42 people with fibromyalgia. Two of its four authors work for THOR Photomedicine, the company that makes the bed. In the library so far we found no whole-body bed trials for brain, mood or autoimmune conditions; those studies used lasers, LEDs or devices worn on the head.
Omnia Lifestyle in Chiswick, West London, offers the NovoTHOR whole-body bed and the THOR laser. In the UK, THOR devices are approved for tendinopathies, chronic joint pain, back and neck pain, and oral mucositis. A free 15-minute consultation can help you decide whether it is right for you.
Getting to our Chiswick clinic
In the UK, THOR devices are approved for tendinopathies, chronic joint pain, and back and neck pain. Research suggests red light therapy may help some people with these problems, alongside exercise and the care your GP gives. A free 15-minute consultation is available.
Omnia Lifestyle, 8 to 9 Bedford Corner, The Avenue, Chiswick, London W4 1LZ. A short walk from Turnham Green station on the District line, with buses 94, E3 and 272 nearby. Limited parking is available on request when booking.
Book red light therapy in Chiswick: THOR laser £80 for 30 minutes, or NovoTHOR £70 for 20 minutes. Book online or call 020 4515 0000.
Last updated 15 October 2026. This page is for information and does not replace advice from your GP.
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8-9 Bedford Corner, The Avenue
Chiswick, London W4 1LZ
A few minutes’ walk from Turnham Green station on the District line.
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