Does Light Therapy Work Through Clothes?
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Mostly no. Red light therapy (rødlysterapi) does not work meaningfully through normal clothing. The wavelengths of red and near-infrared light that drive the biological effects, roughly in the 600nm to 900nm range, are absorbed or scattered by fabric before they reach your skin in any significant dose. That said, the full story is a little more nuanced than a flat no, and the nuance is actually important, because getting this wrong means quietly ruining your own results session after session without ever realising why.
There is also a second problem that almost nobody talks about, which is what certain fabrics are actually doing to you even before light enters the equation. We will get there.
What Is the Light Actually Trying to Do?
Let me start with the biology, because once you understand what is happening at the cellular level, the clothing question answers itself pretty quickly.
The primary target of red and near-infrared light in your body is cytochrome c oxidase, an enzyme complex sitting inside the inner membrane of your mitochondria. Dr. Michael Hamblin at Harvard, one of the most cited researchers in photobiomodulation (fotobiomodulasjon), has described this enzyme as the main chromophore for these wavelengths. When it absorbs light in the right range, it triggers a cascade: electron transfer accelerates, ATP production increases, nitric oxide is released, and redox signalling downstream changes in ways that affect inflammation, cellular repair, and energy metabolism.
This is not a surface effect. This is happening inside the cell.
For that to happen, photons need to travel from the panel, through the air, through your skin, through subcutaneous tissue, and into the mitochondria of the target cells. Every layer they pass through costs them energy. Some photons get absorbed. Some scatter sideways. The deeper you want to go, the more you need to start with.
Fabric sits at the very beginning of that journey, before the light has even reached your skin. And even a single layer of ordinary clothing can absorb or scatter between 30 and 80 percent of incident red light, depending on the weave, the colour, and the material. Dark colours absorb more. Dense weaves scatter more. What arrives at your skin on the other side may be a small fraction of what left the panel.
At that point, you are not delivering a therapeutic dose. You are delivering a vague suggestion of one.
The Gym Tights Problem
Here is where it gets interesting, and where I see a lot of people making a quiet but significant mistake.
Gym tights, compression leggings, athletic base layers, tight running gear. These are thin. Much thinner than a woollen jumper or a heavy fleece. And people assume, reasonably enough, that thin means mostly transparent. So they use the panel while still in their workout clothes, or they treat their legs through their leggings, and they figure the light is getting through well enough.
It is getting through. Some of it. But "some" is doing a lot of work in that sentence.
Even a single layer of thin athletic fabric will typically reduce the effective dose by somewhere between 40 and 70 percent, depending on the material and colour. Light-coloured, very thin fabric sits at the lower end of that range. Dark compression fabric sits at the higher end, sometimes more. You are not blocking everything. But you may be halving your effective dose at best.
Now think about how that connects to the hormesis model. The therapeutic window for photobiomodulation is not infinitely wide. Too little dose means no meaningful biological signal. The research on optimal dose ranges, studied carefully by researchers including Dr. Hamblin and Dr. Alexander Wunsch, shows you need to land within a specific energy delivery range to get the adaptive response you are looking for. Drop below that range and you get... not much.
If you are using a high-powered panel at close range for 15 to 20 minutes, you might just about compensate for what the leggings are absorbing. But if you are using a mid-range panel, sitting slightly further back, or your sessions are shorter, then treating through gym tights may be taking you below the effective threshold entirely. You are not doing nothing. But you may be doing 40 percent of what you think you are. And that, accumulated over weeks and months, is the difference between real results and wondering why you are not seeing them.
I'm going to say something slightly obvious here but it needs saying. Take the leggings off for the session. Or at minimum, if you are targeting legs or glutes specifically, dedicate a few minutes of direct skin exposure to those areas and then put them back on if you are cold.
The Synthetic Fabric Issue Nobody Mentions
This is the second problem, and it exists entirely separately from whether you are using light therapy or not.
Most gym tights, athletic wear, and compression clothing sold today is made from synthetic fibres. Polyester, nylon, elastane, spandex, and various blends of all of these. These materials are petroleum-derived plastics woven into fabric. They are extraordinarily good at what they are designed to do: they stretch, they wick, they hold shape, they dry fast. Nobody disputes that.
But here is what they also do that the product page does not mention.
Synthetic fabrics, particularly when worn tight against the skin, shed microplastics with every movement and every wash. They generate static electricity against the skin. And from a quantum biology perspective, which is the lens I find most useful for this kind of question, they create a physical and electrical barrier between your skin and its environment in a way that natural fibres simply do not.
Dr. Jack Kruse has written and spoken at length about the relationship between the skin's surface charge, grounding (jording), and electron transfer. The skin is not a passive wrapper. It is an interface. It has electrical properties that matter to mitochondrial function. Synthetic fibres, particularly those that generate static, disrupt that interface. They also trap heat differently from natural fibres, interact differently with the skin microbiome, and some research has flagged potential endocrine-disrupting compounds in certain plastics that migrate from fabric to skin under heat and friction conditions.
I am not telling you to throw your workout gear in the bin. I wear synthetic fabrics. Most of us do, it is unavoidable in 2026. But if you are already thinking carefully about your light environment and your circadian biology, and you are reading this post, then this is worth knowing.
For light therapy specifically, the implication is double: synthetic fabric blocks the light AND creates its own problem at the skin surface. Natural fibres, even a thin layer of cotton or linen, are a better choice if you are going to have any fabric between you and the panel. They attenuate the light less and they do not carry the electrical interference issue.
But ideally, as I keep saying: bare skin. Every time.
The Norwegian Season Question Changes Everything
This is where I want to get specific for us in Norway, because the answer to "how much does this actually matter" is genuinely different right now in early April than it was in January.
We are almost into April. The light is back, and not just in terms of hours. The quality is shifting. The sun is climbing higher each day, the UV index is building steadily, and on clear days in Drammen or Oslo or Bergen you are getting a real solar spectrum outdoors in ways that simply do not happen during mørketid. If you get outside in a t-shirt or shorts for 20 to 30 minutes at midday right now, you are getting a meaningful dose of red and near-infrared light from the sun itself. For free. Every single day.
The sun is an incomparably more powerful source of these wavelengths than any panel I sell. The irradiance is extraordinary. It hits your whole body simultaneously. It is full spectrum. And right now in Norway, that resource is returning.
So why does the clothing question still matter in April?
A few reasons. For targeted work, like a joint, a specific area of skin, or muscle recovery after training, the sun is not pointing at your knee for 12 focused minutes. The panel is. For early mornings before you get outside, for cloudy days, and for anything below the waist that you are not routinely sunbathing in April weather, the panel remains useful. But the context is different from winter, and I think it is worth being honest about that.
In mørketid, from October through to February or March, your panel may be doing the heavy lifting for your entire photonic environment. During those months, getting 50 percent of your dose through leggings is the difference between some benefit and none at all, especially if exposing skin in a cold room is genuinely uncomfortable. At that point, knowing your tights are costing you half your dose matters a lot. You might extend the session, move closer, or do a short direct-skin portion before covering up again.
In April, with the sun returning, the stakes of a partially attenuated indoor session are somewhat lower. You are filling in gaps with the panel, not replacing an absent sun. But the synthetic fabric question has no season. That applies in July as much as in December.
One more thing about summer in Norway, because it comes up with customers every year. People who discover red light therapy during mørketid often abandon it entirely in June and July, partly because they feel dramatically better and partly because Norway in summer is hard to argue with and you are not spending much time indoors. That is completely understandable and in many cases totally fine. But for anything targeted, anything relating to joint recovery or specific skin work, summer sun is a supplement, not a replacement for focused application. The sun covers everything broadly. The panel can be precise.
The Glowing Hand Demonstration
One more thing worth addressing, because I get asked about it regularly.
If you shine a red light therapy panel at your hand in a dim room, you can see red light glowing through your fingers and palm. People observe this and conclude that light must pass through tissue pretty effectively, so surely a thin layer of fabric is not that much of a barrier.
What you are actually seeing is a specific demonstration of the optical properties of blood and shallow tissue. Red wavelengths do pass through skin better than shorter wavelengths. This is exactly why pulse oximeters work. But transmission and therapeutic absorption are not the same thing. The photons that made it all the way through your hand and came out the other side were the ones that kept scattering. The ones that got absorbed along the way are the ones that did the biology.
Fabric has different optical properties from tissue. It scatters more aggressively. The glowing hand trick is a party trick, not evidence that a layer of nylon doesn't cost you anything.
The Simple Rule
Bare skin, every time, if you can manage it. Red and near-infrared light do their work at the mitochondrial level, and they need to arrive with enough energy to be absorbed by cytochrome c oxidase. Every layer of fabric between you and the panel reduces the signal.
If gym tights or athletic wear are genuinely unavoidable for a particular session, know that you are taking a meaningful dose penalty, and either adjust for it with more time or closer distance, or direct-expose the key areas briefly before covering up. Understand it is a compromise, not an equivalent.
If the fabric is synthetic and tight against the skin, you have a double reason to think about swapping where possible, not just for light therapy sessions but more broadly.
And if you are in Norway right now as April arrives, go outside in as little as the weather will allow and let the sun do some of the work. The panel is a precision tool. The sun is the source. Use both.
For panels, see the range at https://lighttherapy.no/collections/red-light-panels.
For targeted, joint, and portable options where direct skin contact is easier to maintain, see https://lighttherapy.no/collections/portable-and-specialist.
References
Hamblin, M.R. (2017). Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS Biophysics, 4(3), 337-361. https://doi.org/10.3934/biophy.2017.3.337
Wunsch, A. & Matuschka, K. (2014). A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomedicine and Laser Surgery, 32(2), 93-100. https://doi.org/10.1089/pho.2013.3616
FAQ
Does red light therapy work through clothing? Not meaningfully, no. Fabric absorbs and scatters red and near-infrared wavelengths before they reach the skin in a useful dose. Even a single layer of fabric can cut your effective dose by 30 to 80 percent depending on material and colour. Skin contact is always the better choice.
What about thin gym tights or compression leggings? They reduce the dose significantly, even if they don't block it completely. Depending on the colour and material, you may be getting as little as half the intended dose, possibly less. Over time, that can be the difference between seeing results and quietly wondering why you're not. Take them off for the session where you can.
Is synthetic fabric a specific problem for light therapy? Yes, for two reasons. First, it blocks light less predictably than natural fibres. Second, synthetic fabric creates its own issues at the skin surface including static, microplastic contact, and interference with the skin's electrical interface. Natural fibres are a better choice if any fabric needs to be near the treatment area.
Does the clothing question matter more in winter than summer in Norway? Both, but differently. During mørketid the panel may be your primary source of therapeutic light, so dose losses through clothing matter a great deal. In April and into summer, the sun compensates for a lot, but targeted panel work is still valuable, and the synthetic fabric issue applies year-round regardless of season.
Virker rødlysterapi gjennom treningstights? Det slipper gjennom litt lys, men dosen kan reduseres med 40 til 70 prosent avhengig av materiale og farge. Det er som å gi kroppen halv dose og lure på hvorfor du ikke ser resultater. Bar hud gir alltid best effekt.
Er syntetisk stoff et eget problem? Ja. Syntetiske fibre som polyester og nylon blokkerer lys mer enn naturlige materialer og skaper statisk elektrisitet mot huden. Fra et kvantebiologisk perspektiv forstyrrer dette hudens elektriske grensesnitt. Naturlige fibre er et bedre valg om du trenger noe mellom deg og panelet.
Bør jeg slutte med panelet om sommeren? Ikke nødvendigvis. Solen i april og utover er utrolig verdifull, og du bør absolutt bruke den. Men solen peker ikke presist mot kneet ditt i 12 minutter. For målrettet behandling av ledd, muskler eller hud er panelet fremdeles et nyttig verktøy gjennom hele året.
Disclaimer: This post is for educational purposes only and does not constitute medical advice. If you have a medical condition, please consult a qualified healthcare professional before beginning any light therapy protocol.