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 effectiveness as well as price. When both are switched on, these differences are often not visible. The crucial factors are components that are hardly visible at the time of purchase: the lenses, the driver, and the cooling system.
This page explains the seven factors that truly determine the effectiveness. For each factor, you will also find a question that allows you 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 | Standard on the market | 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 adjustable 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 type of lens 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 safe | "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-reported data | German Institute for Product Testing: Grade 1.1 · CE, RoHS, WEEE · 5-year 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 only a few studies. This is not an additional benefit, but rather a greater distribution of the existing power.
The right question, therefore, is 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 providing comparable value in return.
There's a reason why 660 nm appears in over 400 studies, while neighboring wavelengths have only been investigated in a fraction of those. Weak evidence makes the data sheet longer, but doesn't automatically improve the result.
Red light reaches approximately 1-3 mm, near-infrared about 3-7 mm. A device that only covers one of these two depths can accordingly only achieve one type of application.
Red light works via absorption, not via 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-wavelength light is scattered more strongly in the uppermost 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 here is not just a number meant to sound good. 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 | ||||||||||||||||||||||||||||||||||||||
| 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 |
| above 100 mW/cm² | no proven additional benefit, but ROS excess and heat |
For context: the midday sun delivers approximately 100 mW/cm² in total. Of this, about 20-30 mW/cm² lie within the therapeutic window. A device advertising 200 mW/cm² thus delivers many times what is naturally provided in this range.
Both values are measured correctly. Only one describes what is therapeutically effective. A solarmeter captures the entire spectrum and also includes components outside the therapeutic window. The factor between the two measurements here is 2.2. So, if one provider states 180 mW/cm² and another 80 mW/cm², it could be the same panel.
This does not mean that a weak device is sufficient. Intensity drops 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 effectively dose.
We measure with a spectrometer, state the distance, and additionally publish the solarmeter value. This way, you can compare our specification with other providers, even if our number appears smaller.
The 82 mW/cm² is not a downward compromise, but a deliberate choice: enough reserve for different distances, without unnecessarily overworking 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 begin.
This is a common reason why people give up after a few weeks: too great a distance, too short an application, or a device that is too weak.
Here, the same mechanism as with too high intensity applies, just over time: The ROS signal can tip into oxidative stress. The cell then downregulates instead of upregulates.
Therefore, simply applying for twice as long does not automatically lead to more effect – in an unfavorable case, even less.
Between "too little" and "too much" lies an effective window. Whether you're outside it isn't necessarily noticeable: it doesn't hurt and isn't visible.
That's why time and distance are not just non-binding recommendations, but part of the application.
Starting: For the first week, 2-3 minutes per area, every other day. Then increase to 3-5 applications per week, with a maximum of 20 minutes per area.
| Goal | 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., in the 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. A skin area can receive many times the energy that reaches it just two centimeters away. In this case, the dose calculation from factor 04 is no longer reliable.
Two optics: 60° for the red wavelengths (630/660/670 nm) and 30° for the near-infrared wavelengths (810/830/850 nm).
The Gen300 has 306 LEDs arranged so that the light cones of both optics overlap. Red and infrared light reach the same skin area simultaneously - without gaps or hotspots.
The double-lens design is not an extra, but the prerequisite for six wavelengths to work together effectively.
Here, a different approach is used. Because 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 characteristics are all dependent 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, it is no longer consciously perceived. However, the visual system still registers the fluctuation. Sensitive people may react with restlessness, eye strain, or headaches.
The term "flicker-free" is used very liberally. 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 merely hides it. True flicker-freedom is only possible with a DC driver. This supplies the LEDs constantly, instead of switching them in rhythm. The result is 0 Hz - meaning not just a low value, but no flicker frequency at all.
The crucial question is therefore 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 intentionally generated flickering. The LEDs are switched at a fixed frequency, usually between 10 and 50 Hz.
There is visible light that pulses at 10 to 50 Hz. This is exactly the frequency range that can trigger seizures in photosensitive individuals. With a large-area panel that occupies a large part of the field of view, this is not a purely theoretical risk. Pulsed visible red light therefore does not belong in a panel.
For small devices that are placed directly on the skin, 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 away from the device - and often daily.
We explicitly do not make any health claims based on this. For us, a different standard is useful.
Every living space already has an electromagnetic background noise from house installations, devices, 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 also be implemented.
heilys® Gen panels work with DC drivers. The flicker frequency is 0 Hz.
Pulsing is only possible in 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 from visible pulsed light is eliminated. The visible red wavelengths always run continuously in the panel - consciously and without exception.
For EMF, our values at the application site are at the level of the normal background noise of a residential environment. The device thus adds virtually 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 no longer afterwards.
Passive: silent and cheaper, but limited in terms of heat dissipation. This makes sense for small devices.
Active: technically more complex and not entirely silent, but maintains stable performance. Above a certain power class, active cooling is practically indispensable - a 480-watt panel cannot be effectively passively cooled.
We use active cooling where power 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 present exactly - and by what criterion were they selected?
With what manufacturing tolerance in nanometers is this done?
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 exactly what it's about: 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 irradiation area and number of LEDs — that is, in how much body surface you can treat at once.
Red light does not suppress melatonin production – unlike blue light. Read more about what this means for your evening under Sleep & Recovery. Learn more →
