Red light is not automatically the same as red light. There can be big differences between two devices that both emit red light – in terms of effect as well as price. When both are switched on, these differences are often not visible. The crucial components are those that are barely visible when purchasing: the lenses, the driver, and the cooling.
This page explains the seven factors that actually determine the effect. For each factor, you will also find a question that you can use to check it yourself – for any provider, including us.
If you're currently comparing and have little time, this is the short version. The reasoning for each line is below.
| Factor | What matters | Market standard | heilys® |
|---|---|---|---|
| 01Wavelengths | The right ones, not the most | 2 (660 + 850 nm) | 6, selected according to CCO curve, study data and penetration depth · tolerance ± 5 nm |
| 02Control | Precisely controllable and easy to use | hardwired, one switch | each wavelength individually dimmable · 6 presets + 12 custom · touch display, app, and one-button remote control |
| 03Irradiance | Within the effective window, not at maximum | Specification without distance and measurement method | 82 mW/cm² at 15 cm (spectrometer) · 182 (solarmeter) — both published |
| 04Dosage | Adjustable, because too much is as ineffective as too little | fixed power | continuously dimmable, timer, time and distance specified per application |
| 05Homogeneity | No hotspots, even illumination | one lens type for everything | Gen-Panels: two lenses, 60° Red / 30° NIR · FaceMask 2.0: narrower LED spacing |
| 06Light Quality | True flicker-free, low EMF, pulsing only where harmless | "flicker-free" without specifying the technology | DC driver → 0 Hz · EMF at ambient levels · pulsing only on NIR |
| 07Proof | Independently tested, not self-proclaimed | Self-declared | German Institute for Product Testing: Grade 1.1 · CE, RoHS, WEEE · 5 years warranty |
The light output of a panel is limited. Each additional wavelength receives a share of a total budget that does not increase. If a device uses ten wavelengths, it distributes the same energy across more channels. This includes wavelengths for which there are few studies. This is not an additional advantage, but a greater distribution of existing power.
The right question is therefore not "how many?", but "by what criteria were they selected?" Three criteria are decisive:
The absorption curve of cytochrome c oxidase has peaks and valleys. 830 nm is at a peak value. If light is applied to a weak area of the curve, it costs energy without delivering comparable value.
There's a reason why 660 nm appears in over 400 studies, while neighboring wavelengths have only been examined in a fraction of them. Weak evidence may make the data sheet longer, but it doesn't automatically make the result better.
Red light reaches about 1-3 mm, near-infrared about 3-7 mm. A device that only covers one of these two depths can therefore only achieve one type of application.
Red light works via absorption, not heat. Between 600 and 900 nm - the therapeutic window - light hits the enzyme cytochrome c oxidase in the mitochondria, increasing ATP production there.
Outside this range, less useful things happen: Short-wave light is scattered more strongly in the top millimeters. Infrared above 1000 nm is absorbed by water and primarily generates heat.
Most panels use 660 and 850 nm. The reason is simple: these LED types were originally produced in large quantities for plant lighting and are therefore inexpensive. This is the obvious, but not automatically the best-justified, choice.
heilys® uses six wavelengths with a manufacturing tolerance of ± 5 nm. Together, they cover around 82% of the CCO absorption curve (Tran et al., 2024).
Six is not just a number meant to sound good here. It is the result of the three filters mentioned.
| Wavelength | Depth | Studies | Why it's included |
|---|---|---|---|
| 630 nm | 1–3 mm | 200+ | Skin, collagen formation, anti-inflammatory |
| 660 nm | 1–3 mm | 400+ | best-studied wavelength ever |
| 670 nm | 1–3 mm | 150+ | ATP production, retina, neuroprotection |
| 810 nm | 3–7 mm | 300+ | deep tissue, muscles, brain |
| 830 nm | 3–7 mm | 250+ | Peak value of CCO activation |
| 850 nm | 3–7 mm | 180+ | Tendons, joints, immune modulation |
Here, two requirements meet that can easily get in each other's way. Nevertheless, both must be met.
Photobiomodulation is a young field of research. A device with a fixed factory setting reflects the state of research from its production year - and permanently remains at that state.
Added to this is the individual factor: skin type, body structure, age, goal, and tolerance differ. Only if settings can be readjusted and saved can one find out what works for their own application.
Many technically good devices fail here. If you have to go through three menu levels for an application, it quickly won't get done after a long day at work.
Red light is applied regularly over weeks. The user interface does not determine the effect of the light itself, but it does determine whether the device will be used regularly at all.
Standard panels are often hardwired: one switch, everything on. At the other end are devices with such overloaded apps that in the end only one mode is used anyway.
For precision: Each of the six wavelengths is individually dimmable. In addition, there are 6 well-founded presets, 12 freely configurable programs, and lifelong software updates.
For everyday use: Touch display, app, and a remote control with a quick-start button. One press is enough, and the last saved setting starts.
Full control when you need it - and a button when you don't.
The checking question: How many steps do I need to start my usual application? If it's more than one, ask yourself: will I really do these daily?
Light works in the cell via a signal. When light hits cytochrome c oxidase, a small and controlled amount of reactive oxygen species is briefly produced. It is precisely this signal that triggers adaptation: more ATP, better cellular respiration, and regeneration.
If the intensity is too high, the cell produces more ROS than its antioxidant systems can neutralize. The signal turns into oxidative stress. The cell then doesn't ramp up, but switches into a protective mode. Excess energy can cause harm where regeneration should actually be supported. Too high intensity can therefore reverse the desired effect.
| Application | Sensible Irradiance |
|---|---|
| Skin, anti-aging, wound healing | 20–50 mW/cm² |
| Muscles, joints, deep tissue | 70–100 mW/cm² |
| Target range universal device | 40–100 mW/cm² |
| over 100 mW/cm² | no proven additional benefit, but ROS excess and heat |
For context: The midday sun delivers a total of around 100 mW/cm². Of this, about 20-30 mW/cm² are within the therapeutic window. A device that advertises with 200 mW/cm² thus delivers many times what is naturally intended in this range.
Both values are measured correctly. Only one describes what is therapeutically effective. A solarmeter captures the entire spectrum and also includes parts outside the therapeutic window. The factor between the two measurements here is 2.2. If one provider states 180 mW/cm² and another 80 mW/cm², the same panel could be behind it.
This does not mean that a weak device is sufficient. The intensity falls with the square of the distance. A panel with 30 mW/cm² at 15 cm is practically ineffective at 50 cm.
Reserve in the device, moderate intensity in application. What you cannot regulate downwards, you cannot meaningfully dose.
We measure with a spectrometer, state the distance, and additionally publish the solarmeter value. This way, you can compare our data with other providers, even if our number appears smaller as a result.
The 82 mW/cm² is not a compromise downwards, but a conscious choice: enough reserve for different distances, without unnecessarily overwhelming the cells.
Irradiance describes how quickly energy arrives. Dosage, on the other hand, describes how much energy arrives overall.
The cells receive light, but the amount remains below the threshold at which enzyme activity measurably changes. The effect is then not just weaker - it may not even occur.
This is a common reason why people give up after a few weeks: too great a distance, too short an application, or too weak a device.
Here, the same mechanism as with too high intensity applies, but over time: the ROS signal can tip into oxidative stress. The cell then down-regulates instead of up-regulating.
Therefore, simply applying for twice as long does not automatically result in more effect - in the worst case, even less.
Between "too little" and "too much" lies an effective window. You don't necessarily notice if you're outside it: it doesn't hurt and isn't visible.
Therefore, time and distance are not just non-binding recommendations, but part of the application.
Starting: In the first week, 2-3 minutes per area, every other day. Then increase to 3-5 applications per week, maximum 20 minutes per area.
| Target | Dose | Distance | Duration |
|---|---|---|---|
| Skin, Anti-Aging | 3–15 J/cm² | 45–60 cm | approx. 8 min. |
| Joint pain | 10–40 J/cm² | 15–30 cm | approx. 10 min. |
| Muscle regeneration | 20–50 J/cm² | 15–30 cm | approx. 12 min. |
| Energy and vitality | 10–30 J/cm² | 30–60 cm | approx. 10 min. |
| Wound healing | 10–40 J/cm² | 15 cm | approx. 7 min. |
| Sleep and recovery | 3–15 J/cm² | 30–45 cm | approx. 7 min. |
| Eyes (670 nm) | 3–15 J/cm² | 30 cm | 1–5 min., morning |
Reference values at approx. 80 mW/cm². "10 minutes daily" without specifying the distance is not a complete dosage — without distance, the dose cannot be determined.
A panel is not just a single light source, but consists of hundreds of individual LEDs. With uneven illumination, there is not one dose, but many different ones. One skin area can receive many times the energy that arrives only two centimeters away. In that case, the dose calculation from Factor 04 is no longer reliable.
Two optics: 60° for red wavelengths (630/660/670 nm) and 30° for near-infrared wavelengths (810/830/850 nm).
The Gen300 features 306 LEDs arranged so that the light cones of both optics overlap. Red and infrared light simultaneously reach the same skin area - without gaps or hotspots.
The dual-lens design is not an extra, but the prerequisite for six wavelengths to work together effectively.
Here, a different approach is used. Since the mask lies directly on the face, the distance between the individual LEDs has been reduced.
More closely spaced light points result in significantly more uniform illumination at short distances.
The goal remains the same: In the end, every part of the skin should receive the same dose.
Three properties all depend on the same component - the power supply unit - yet are hardly ever found on a data sheet.
Flicker is a visual effect: the brightness of the light fluctuates, usually in sync with the mains frequency. Above a certain frequency, this is no longer consciously perceived. However, the visual system still registers the fluctuation. Sensitive individuals may react with restlessness, eye strain, or headaches.
The term "flicker-free" is used very generously. Many manufacturers only mean that the frequency is so high that the flicker is above the threshold of conscious perception.
Invisible flicker is still flicker. A higher frequency does not eliminate the brightness fluctuation, but only hides it. True flicker-free operation is only possible with a DC driver. This supplies the LEDs constantly instead of switching them on and off. The result is 0 Hz - not just a low value, but no flicker frequency.
Therefore, the crucial question is not just "Is it flicker-free?", because almost everyone answers yes to that. It is: "Does the device operate with direct current, and what is the flicker frequency in Hertz?"
Pulsing is deliberately generated flicker. The LEDs are switched at a fixed frequency, usually between 10 and 50 Hz.
There is visible light that pulsates at 10 to 50 Hz. This is precisely the frequency range that can trigger seizures in photosensitive individuals. With a large-area panel that occupies a large part of the field of vision, this is not a purely theoretical risk. Pulsed visible red light therefore does not belong in a panel.
With small devices that lie directly on the skin at specific points, the situation is different: there, the light source is on the skin and not in the field of vision.
Every power supply generates an electromagnetic field. For red light applications, you are often 15 to 60 cm from the device - and often daily.
We explicitly do not derive any health claims from this. For us, a different standard is appropriate.
Every living space already has an electromagnetic background noise from house installations, appliances, and power supplies.
A well-designed red light device should not significantly increase this existing level. This is technically feasible. And what is feasible should be implemented.
heilys® Gen-Panels use DC drivers. The flicker frequency is 0 Hz.
Pulsing is only possible with the NIR spectrum and can be selected in the app between 10 and 50 Hz. Near-infrared is invisible, so the risk of photosensitive reactions due to pulsed visible light is eliminated. The visible red wavelengths in the panel always run continuously - intentionally and without exception.
Regarding EMF, our values at the application site are at the level of normal background noise in a residential environment. The device therefore adds practically nothing to the environment.
LEDs lose light output when their junction gets hot. They also age faster. Then your dose calculation might be correct in the first minute, but not later.
Passive: silent and cheaper, but limited in the heat that can be dissipated. This is useful for small devices.
Active: technically more complex and not completely silent, but keeps performance stable. Above a certain power class, active cooling is practically indispensable - a 480-watt panel cannot be effectively passively cooled.
We use active cooling where performance demands it: in all Gen-Panels and FullBody-Panels as well as in Gen30 and Gen50. The smaller devices manage with passive cooling.
The fans run quietly: approx. 36 dB at 15 cm and approx. 33 dB at 50 cm - roughly in the range of whispering.
100,000 hours LED lifespan · 5 years warranty · 30-day return policy · CE, RoHS, WEEE DE 19301058 · Developed and tested in Germany.
Independently tested
The heilys® Gen300 was rated 1.1 by the German Institute for Product Testing. To the test report →
Which wavelengths are precisely present - and by what criterion were they selected?
What is the manufacturing tolerance in nanometers for this?
What is the irradiance, at what distance, and with what measuring device?
Can I control individual wavelengths, save my own settings - and how many steps does it take to start an application?
How is uniform illumination achieved: via different lenses or via LED spacing?
Does the driver operate with direct current and what is the flicker frequency in Hertz?
Is visible light pulsed - and what is the EMF in relation to the background noise in the room?
How is it cooled, how loud is it, and who has independently tested the device?
We answer all eight questions on this page. If another provider can do the same - very good. That's precisely the point: you shouldn't just believe us, but be able to compare the devices yourself.
All Gen-Panels have the same six wavelengths, the same app control, and the same dimming function. They differ only in irradiance area and LED count — that is, how much body surface area you can treat simultaneously.
Red light does not suppress melatonin production – unlike blue light. What this means for your evening, you can read under Sleep & Recovery. Learn more →
