Incandescent vs LED Lights in Red Light Therapy


Red Light Therapy has been investigated in thousands of research studies over the last 50 years. Until the early 2000’s, most studies used lasers as the light source, but more recently, LED lights have become popular due to their affordability, safety, and ease of at-home use. LED lights are now widely used in Red Light Therapy devices, including the devices we make at Fringe.
Other light sources, such as incandescent lights, are also sometimes promoted for use in Red Light Therapy, but it’s important to recognize that incandescent lights are not equivalent to LED’s when it comes to reaping the well-recognized benefits of this powerful healing modality.
In this article, we’ll explore the characteristics of LED and incandescent lights, how the two light types can (and cannot) be used in Red Light Therapy, and what to look for in a Red Light Therapy device.
Comparison of LED and Incandescent Lights
LED lights have many important characteristics that are superior to incandescent lights, including:
Characteristics | LED | Incandescent |
Energy Efficiency | 80-90% more efficient than incandescent, as most energy is converted to light | Very inefficient – 90 to 95% of energy is lost as heat, and only 5 to 10% is converted to light |
Lifespan | 25,000 to 50,000 hours (10 to 25x longer than incandescent) | 1,000 to 2,000 hours (needs frequent replacement |
Heat Output | Minimal heat emission, stays cool to the touch | High heat emission, can become too hot to touch |
Long-Term Cost | Lower long-term cost due to energy savings and longer lifespan | Higher long-term cost due to frequent replacements and high energy use |
Durability | Shock-resistant, does not break easily | Fragile, glass can break easily |
Environmental Impact | Eco-friendly, no toxic materials, low energy consumption | Higher energy use, shorter lifespan, increases waste |
There are also some areas where LED’s can be inferior to incandescent lights, including:
Characteristics | LED | Incandescent |
Flicker Potential | Some LEDs flicker which can cause eye strain | No flicker; provides continuous, steady light |
EMF Emission | May emit higher EMF’s due to electronic drivers | Minimal EMF emission, since it does not use electronic drivers |
Blue Light Exposure | Can be quite high | Low, more natural warm light |
However, NONE of these characteristics are necessarily an issue with Red Light Therapy devices.

Why we don’t NECESSARILY need to be concerned about these limitations (Flicker, EMF, Blue Light Exposure) with Red Light Therapy devices:
- Many Red Light Therapy devices do not flicker – a reputable company will demonstrate this using third party testing (we do!)
- EMF emission – it’s absolutely true that a LOT of Red Light Therapy devices emit way too many EMF’s, but they don’t have to. At Fringe, we’ve designed our panels so that the electronic driver is 3 feet away from the panel, so there is almost no EMF emission from the panel itself. And our wraps are battery powered; batteries create energy through chemical reactions, which generate negligeable EMF’s.
- Blue Light Exposure – Red Light Therapy devices contain red and near infrared LED’s, which don’t emit blue light (of course, blue light LED’s are also an option…!)
What about Blue Light Therapy using LED’s? Isn’t blue light from LED lights harmful?
- This is true but isn’t the whole story.
- Blue light from devices like ipads, phones, etc. is found in a very narrow spectrum of wavelengths. This is “foreign” to our body, as it is different than the blue light that comes from the sun.
- In contrast, blue light used in Blue Light Therapy emits a wider spectrum of wavelengths that closely mimics the distribution of blue light in sunlight. This light spectrum has been found to be antimicrobial, which is why it is used for applications like acne.
- No matter what, though, it’s still important to avoid getting blue light in the eyes.

Is light from an incandescent light the same as from an LED?
- Incandescent lights produce light in a “full spectrum”, including red and near (and also far) infrared light. This is what makes the light from incandescents “warm” in terms of color, and also generates a lot of heat, making them hot to the touch. It’s also why these lights are used for things like heating terrariums. In order to make an incandescent light exclusively red, a red film or coating is placed on the glass that filters out other colors allowing only the red (and sometimes infrared) wavelengths to pass through. The filament inside still produces other colors, but they’re mostly blocked by the coating.
- LED lights used in Red Light Therapy will produce light in the red (if using red diodes) or near infrared (if using near infrared diodes) spectrums. Many devices include both types of diode, and the type of light is produced by using a semiconductor material that naturally produces red or near infrared light. Red Light Therapy doesn’t use white LED lights like you would find in a house lamp.
- Red and near infrared light are the same in terms of wavelength no matter what the source. The difference is that incandescent lights produce full spectrum light and then block the other light from being emitted, while LED lights (red or near infrared) emit ONLY the light in that color spectrum.
If the red and near infrared light is the same, can incandescent lights be used instead of LED’s in Red Light Therapy?
- Incandescent lights CAN be used to activate the eye to brain pathway that is responsible for some of the benefits of Red Light Therapy. In this pathway, photoreceptors in the retina are activated and influence the function of the suprachiasmatic nucleus in the brain. This helps regulate the circadian cycle and also has an influence on mood and stress hormones. These lights are great for lighting up a room.
- Incandescent lights CANNOT be used as easily as LED’s to activate the light to tissue pathway that is responsible for the majority of benefits of Red Light Therapy. In this pathway, light enters through the skin (or other tissue) and activates photoreceptors in cells, such as cytochrome c oxidase in mitochondria. To achieve this benefit, the skin/tissue has to be close (6 inches or less) away from the light source. Because incandescent lights get hot and are fragile, they aren’t a substitute for durable LED’s that don’t generate much heat. Incandescent bulbs also generate scattered light, which doesn’t allow for good skin/tissue penetration. There is limited research showing that under some circumstances, incandescent lights may activate this pathway, but their functional limitations do not make them a substitute for LED’s.
- Most of the benefits of Red Light Therapy (reduced inflammation, faster tissue healing, reduced oxidative stress) comes from the light to tissue pathway. Incandescent lights do not work to activate this pathway effectively.
- It’s also important to note that almost none of the benefits of Red Light Therapy that have been observed in thousands of research studies over the last 50 years used incandescent light, with most studies using laser or LED light.
How do I know if my Red Light Therapy device is safe to use?

Here are some things to look for:
- Use of red and near infrared light in evidence-based spectrums. Fringe Red Light Therapy devices use red light at 660nm and near infrared light at 850nm, which have been demonstrated in many research studies to be beneficial.
- No flicker.
- Low to no EMF’s.
- Low irradiance (this is also called power or intensity. And yup, you want this low. A lot of companies are selling products that are quite high intensity, and this can potentially be harmful). Irradiance in the range of 20-40mW/cm2 mimics the sun, and has been shown in multiple research studies to be both safe and effective.
- A good company will prove these things by sharing analyses done by third party testing. Don’t trust them if they don’t prove it.
Why choose Fringe Red Light Therapy devices?
- We use evidence-backed wavelengths of red and near infrared light.
- Our devices are no flicker and generate low to no EMF’s.
- We use a safe and effective sun-like intensity of light, at between 20 and 40mW/cm2.
- All of our products are tested by an independent third party lab, and we share this analysis with our consumers.
- Our products are created by a team of medical professionals who carefully review and use published scientific evidence to inform how we manufacture.

Take home message:

- Incandescent lights are a great option for lighting up a room, creating a warm and ambient red light that may have benefits related to activation of the eye to brain pathway which helps to regulate the circadian rhythm and mood.
- Incandescent lights cannot be used as a substitute for LED lights to activate the tissue to cell pathway that is responsible for benefits including reduced inflammation, decreased oxidative stress, and improved tissue healing.
- Of the thousands of research studies on Red Light Therapy, only a small number used incandescent lights, so their clinical efficacy has not been clearly demonstrated.
- High-quality Red Light Therapy devices will use both red and near infrared LED lights and will be no flicker, generate low to no EMFS, and deliver light at a sun-like intensity that is both safe and effective for everyone, including kids and pets.
about the author
Dr. Genevieve Newton, DC, PhD spent close to 20 years as a researcher and educator in the field of nutritional sciences before joining Fringe as its Scientific Director. Gen’s job is to “bring the science” that supports Fringe’s products and education. She is passionate about all things Fringe, and is a deep believer in healing body, mind and spirit using the gifts of the natural world.
The contents in this blog; such as text, content, graphics are intended for educational purposes only. The Content is not intended to substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your healthcare provider.

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