Is Your Red Light Panel Actually Working? The Irradiance Question
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Is Your Red Light Panel Actually Working? The Irradiance Question
Most red light panels sold in Norway (and globally) are either using solar meters to generate inflated irradiance figures, or publishing manufacturer numbers they never actually verified. A panel claiming "100+ mW/cm² at 30cm" is almost certainly measured incorrectly. Real spectrometer measurements of quality panels typically show 20 to 40 mW/cm² of therapeutic wavelengths at 30cm — which is still enough to achieve a therapeutic dose, but only if you know the actual number and use it correctly. Without accurate irradiance data (irradians), you are either under-dosing and seeing no results, or overdosing past the point where the research shows benefits disappear.
You're researching rødlysterapi panels. You visit a few websites. They all claim the same thing: "100+ mW/cm² at 30cm distance!" or even "150 mW/cm² at 6 inches!" Sounds impressive. Sounds powerful. Sounds like you're getting therapeutic dosing.
Here's the problem: they're either lying, making it up, or using the wrong measurement equipment.
And if you buy based on those numbers, you're either getting zero benefit or overdosing into the biphasic response zone where benefits disappear. I have seen this happen to customers repeatedly. They come to me after months of consistent use, frustrated that nothing is happening, and the first thing I do is check what they're actually getting in their sessions.
Let me explain why irradiance data matters more than almost anything else when buying red light therapy devices (rødlysterapi paneler), and why most sellers in Norway and globally are misleading you.
What Irradiance Actually Means
Irradiance is power density. It's measured in milliwatts per square centimeter (mW/cm²), and it tells you how much light energy is hitting your skin per unit area at a given distance.
Why does this matter? Because every single research study on fotobiomodulasjon uses specific irradiance values to achieve specific effects. Too little? Nothing happens. Too much? You go over the peak of the dose-response curve and benefits disappear or reverse.
Think of it like cooking. The recipe says bake at 180°C for 30 minutes. If your oven is actually running at 120°C, your food won't cook properly. If it's running at 250°C, you'll burn everything. The temperature matters. Irradiance is your "temperature" for red light therapy. Get it wrong, and nothing works correctly — regardless of how good the panel looks or how expensive it was.
The Solar Meter Problem
Here is how most red light panel sellers generate their impressive-sounding numbers: they use solar meters (solarmåler).
Solar meters are designed for measuring sunlight or grow lights. They measure a broad sweep of visible light — roughly 400nm to 700nm and often well beyond. They were never designed to measure the narrow-band therapeutic output of red and near-infrared LEDs. When you point one at a red light panel, it picks up the red wavelengths you want, plus ambient room lighting, reflections off walls, and anything else emitting photons nearby. It gives you a combined reading and has no way to distinguish which photons are therapeutically relevant.
So when a seller claims "150 mW/cm² at 30cm" measured with a solar meter, they are giving you a completely useless number. That's like measuring your oven temperature by including the heat from your boiler, the sun through the window, and the toaster on the counter. It sounds precise. It tells you nothing.
The correct tool is a spectrometer (spektrometer) — a device that measures irradiance at specific, individual wavelengths across the spectrum. When I test a panel's 660nm output, I am measuring actual 660nm photons hitting the sensor, not 660nm plus everything else. That is the number that tells you something real about what your cells are receiving.
What Real Irradiance Looks Like
Here is what spectrometer-measured irradiance actually looks like for well-built panels — the kind of numbers you should expect when someone is being straight with you:
| Distance | Combined red + NIR (spectrometer measured) |
|---|---|
| 5cm | 150 to 200+ mW/cm² |
| 15cm | 80 to 120 mW/cm² |
| 30cm | 20 to 40 mW/cm² |
| 45cm | 10 to 20 mW/cm² |
Notice something? These are considerably lower than what most sellers claim. That is not because the panels are weak — it is because these are real measurements of actual therapeutic wavelengths, not solar meter readings inflated by ambient light and off-spectrum output.
When another Norwegian seller claims "100+ mW/cm² at 30cm," they are almost certainly doing one of four things: using a solar meter, publishing manufacturer specs they never tested, measuring at an unrealistically close distance, or making the number up entirely. I know which applies to most sellers here because I have tested panels that customers brought to me asking why they were not getting results.
The good news is that 20 to 40 mW/cm² at 30cm is perfectly adequate for most therapeutic protocols — research studies have shown positive effects across a range of conditions at these power densities. The point is not that lower numbers mean a weaker panel. The point is that you need to know your actual number so you can use the device correctly.
The Biphasic Dose Response: Why This Actually Matters
This is the concept that turns the irradiance question from a technical curiosity into something that directly affects whether your sessions work.
Red light therapy follows what researchers call a biphasic dose response — sometimes referred to as the Arndt-Schulz curve. There is an optimal dose range where cellular benefits are maximised. Below that range, insufficient stimulation occurs. Above it, benefits decrease or disappear entirely, and at high enough doses, cellular function can actually be suppressed. This is not theory. It has been documented in cell studies, animal models, and human trials for decades. Hamblin and Huang at Harvard's Wellman Center published the definitive reviews of this phenomenon — you can read the original 2009 paper here and the 2011 update here.
The implication for anyone buying a panel is direct: without accurate irradiance data, you have no idea where you are on that curve. You are flying blind.
Say you read a study showing that 850nm light at 40 mW/cm² for 10 minutes produces a measurable benefit for knee pain recovery. You want to replicate that at home. You buy a panel claiming "100+ mW/cm² at 30cm" — but it is actually delivering 15 mW/cm² of therapeutic wavelengths at that distance, because the seller used a solar meter. You stand 30cm away for 10 minutes thinking you're hitting the research dose. You're getting less than half of it. Nothing happens. You conclude red light therapy doesn't work.
Or the reverse scenario: the panel really is powerful, but the seller's inflated numbers lead you to use it closer than you should for longer than you should. You overdose past the biphasic peak. Cellular function is suppressed rather than enhanced. You feel worse than when you started.
Both scenarios happen. I have had customers land in both situations. The fix, in every case, is accurate data from the start.
What Happens When You Have the Right Data
When you buy from me, you get actual spectrometer-measured irradiance at multiple distances, a specific wavelength breakdown for your device, and the research parameters that show what studies used for the results you are interested in. Not because I enjoy running measurements — though honestly, I do find this stuff interesting — but because it is the only way to give you anything genuinely useful.
Here is the practical part. Every panel varies in irradiance from its centre outwards. Everyone's biology is different. Giving you a one-size protocol of "10 minutes at 30cm" would be pointless without knowing what your specific device is delivering at 30cm in the first place, and without accounting for your particular goals and situation.
What I give you is the foundation: measured data and research context. Then you experiment within those parameters to find what works for your body. Closer for higher intensity over smaller areas. Further away for lower intensity over larger areas, for longer sessions. Adjust time to adjust dose. Pay attention to how your body responds. The research on fotobiomodulasjon consistently shows this personalised approach beats rigid protocols every time.
This level of tested, verified data exists at no other red light therapy store in Norway. I know because I have checked. Most give you nothing. Some give you manufacturer specs they never verified. None provide spectrometer measurements from actual testing.
Why Norway Makes This Particularly Important
For us in Norway, this is not just an abstract consumer protection issue. Most of us use our rødlysterapi paneler year-round, but the stakes are highest during mørketid — October through to March — when the panel may be doing the heavy lifting for photonic input that the sun normally handles.
If you are relying on a panel as your primary source of red and near-infrared light during those months, and it is delivering half the dose you think it is, you are missing the benefit during exactly the period you need it most. Getting this right matters.
The red light therapy panel collection at LightTherapy.no lists spectrometer-measured irradiance data for every device. If you have questions about which panel fits your specific situation and goals, get in touch directly — I'll give you the measured numbers and help you work out what protocol makes sense.
FAQ
What is irradiance in red light therapy and why does it matter? Irradiance (irradians) is the measure of light power per unit area hitting your skin, expressed in mW/cm². It is the single most important variable for determining whether you are getting a therapeutic dose. Too low and the biological response doesn't occur. Too high and you can go past the biphasic peak where benefits reverse. Every research study uses specific irradiance values — without knowing yours, you cannot replicate what those studies found.
What is a good irradiance for a red light therapy panel? Quality panels measured correctly with a spectrometer typically deliver 80 to 120 mW/cm² at 15cm and 20 to 40 mW/cm² at 30cm for therapeutic wavelengths. Research studies have shown positive effects at power densities throughout this range. The key is that you know the real number for your device at your treatment distance so you can adjust session time accordingly.
Why do sellers claim 100+ mW/cm² at 30cm if that's inaccurate? Almost always because they are using a solar meter rather than a spectrometer. Solar meters are cheap, widely available, and will show a much higher reading than a spectrometer because they capture all visible light plus reflections and ambient sources, not just the therapeutic wavelengths the LEDs are actually producing. Some sellers genuinely do not know the difference. Others do and use it anyway. Either way, the number is meaningless for therapeutic dosing.
What is the biphasic dose response in red light therapy? It is the well-documented phenomenon where low-to-moderate doses of red and near-infrared light produce beneficial cellular effects, but high doses reduce or eliminate those effects. Published first by Hamblin and colleagues at Harvard, and described using the Arndt-Schulz curve, it means that more is not better once you pass the optimal window. This is why accurate irradiance data is essential — without it you cannot know whether you are in the therapeutic range or past it.
Does Norwegian mørketid affect how important irradiance accuracy is? Yes, practically speaking. During mørketid, from October through to late February or March, most of us are relying on our panel as a primary source of red and near-infrared light. If that panel is delivering half the dose you believe it is, you are significantly under-dosing during the period you most need the benefit. Getting the data right matters more when the panel is carrying the load the sun normally handles.
Hva er irradians og hvorfor er det viktig ved rødlysterapi? Irradians (irradiance) er målet på lyskraft per flateenhet (mW/cm²) som treffer huden din ved en gitt avstand. Det er den viktigste variabelen for å avgjøre om du faktisk får en terapeutisk dose. For lav irradians gir ingen biologisk respons. For høy irradians kan du overstige det bifasiske terapeutiske vinduet der fordelene reverseres. Alle forskningsstudier bruker spesifikke irradiansverdier — uten å kjenne din faktiske irradians kan du ikke replikere studieresultatene hjemme.
Kan jeg bruke et solarmåler til å sjekke panelet mitt? Ikke på en meningsfull måte. Solarmålere er kalibrert for bredspektret sollys og gir oppblåste avlesninger for terapeutiske LED-er — typisk det dobbelte eller mer av faktisk terapeutisk utgang. For å få pålitelige tall trenger du et spektrometer kalibrert for de spesifikke bølgelengdene rødt og nær-infrarødt lys. Hvis en selger bare kan tilby solarmålermålinger, vet du at tallene ikke forteller deg det du trenger å vite.
References
Huang YY, Chen AC, Carroll JD, Hamblin MR. Biphasic Dose Response in Low Level Light Therapy. Dose-Response. 2009;7(4):358-383. PMC Full text
Huang YY, Sharma SK, Carroll JD, Hamblin MR. Biphasic Dose Response in Low Level Light Therapy — an Update. Dose-Response. 2011;9(4):602-618. PMC Full text
Hamblin MR. Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation. Photochemistry and Photobiology. 2018;94(2):199-212. PMC Full text
Questions about irradiance measurements or which panel specifications make sense for your goals? Contact me directly. I will provide actual spectrometer-measured data and specific parameters for your situation. Because that is what serious red light therapy actually requires.