What is Red Light Therapy?

What is red light therapy?

Because I have spine and joint issues, I am always looking for ways to reduce pain. “Red Light Therapy” promises relief from head to toe. What is “Red Light Therapy,” and does it work?

Red Light Therapy is the use of red and infrared energy to help the body heal. It does work, with scores of studies backing it up. Users find improvements in skin, muscles, joints, bones and the brain.

It’s not the heat that heals. The body accepts the light photons, and uses them to create cellular energy.

Red Light Therapy is not “laser” therapy, although the names can be very confusing (I’ll show you how to separate one from the other).

Is Red Light Therapy Actually Red?

Red light therapy uses light in the red and the infrared spectrum. You can see red, but infrared is invisible.

The “red” in red light therapy refers to both the red color and the infrared energy that we cannot see. When we say “red,” the “and infrared” is implied. Red Light Therapy means “therapy using red light” and “therapy using infrared energy.”

Why is Red Light Therapy “Light”?

Light is a form of energy. Our cells are able to absorb this energy. When the body’s cells receive the right kind of light, it starts a healthy chain reaction.

Does Red Light Therapy Use Laser Light?

Red Light Man red light
Red Light Man red light

Red Light Therapy designed for home use does not use lasers.

Most consumer red light devices use light-emitting diodes (LED) bulbs.

Lasers are much too strong for home use. They can cause permanent eye damage and burns.

The red light therapy devices available to consumers today evolved from laser therapy devices invented in 1967. The slow evolution from laser to LED created naming confusion that is prevalent today.

For example, Low Level LASER Therapy (LLLT) is a poor attempt at saying “it’s like a laser, but with less energy.” LLLT refers to a non-laser light source, so it is just a confusing term. So are “cold laser” and “soft laser,” which also refer to non-laser treatments.

Scientists changed the “Laser” to “Light,” creating “Low Level LIGHT Therapy.” This is a much more accurate name for red light therapy.

Does Red Light Therapy Use Heat?

Red Light Therapy is the therapeutic use of non-thermal light. Infrared can produce heat, but red light therapy does not include infrared for its heat production quality. The cell’s photoreceptors accept red and infrared photons without a heating effect.

As the light therapy field grew, organizations interested in nailing down the correct name grew as well. The North American Association for Light Therapy and the World Association for Laser Therapy.

They settled on “Photobiomodulation,” which is the ability to change biology by applying non-ionizing, non-thermal light.

Non-ionizing light is too weak to damage DNA. Non-thermal light is too weak to heat tissue.

Photobiomodulation excludes infrared heat and laser light, as both are thermal modalities.

Photobiomodulation includes all non-thermal light modalities: red light therapy, blue light therapy, etc, as well as infrared when used for its photon energy rather than its heating ability.

The names below refer to red, blue, and other therapeutic light therapy modalities that use low energy rather than lasers.

Photobiomodulation subsumes “cold,” “low-level” and “low intensity” previous names for non-ionizing, non-thermal light therapy.

Non-Laser, Non-Thermal Therapies (any use of “laser” in an error in the term):

  •   Photobiomodulation is the standardized term that includes Color Light and Infrared therapy
  • Red Light Therapy
  • Blue Light Therapy
  • Amber Light Therapy
  • Orange Light Therapy
  • Low Level Light Therapy
  • Low Intensity Laser Therapy
  • Low Level laser Therapy
  • Low Power Laser Therapy: Incorrect use of
  • Cold Laser
  • Soft Laser

Laser, Non-Laser, Thermal, or Non-Thermal Energy Therapies

  • Photodynamic Therapy
  • Photobiostimulation
  • Laser Biostimulation


Can Red Light Therapy Give You a Tan?

No, red light therapy cannot tan your skin. The skin has a tanning response when exposed to ultraviolet (UV) radiation. Tanning lights and the sun emit the UV frequency.

UV radiation is dangerous, as it causes skin cancer. Red Light Therapy devices do not emit UV rays.

How are UV, Red, and Infrared Energies Different?

UV and Infrared light are invisible to the human eye. Red is visible.

Another way to differentiate UV, red, and infrared light is by their wavelengths.

A wavelength is the distance between cycles of energy from peak to peak.

Frequency is how many times the energy wavelength peaks in one second.

The more peak-to-peak cycles the energy has in one second, the shorter the wavelength.

Shorter wavelengths have more energy.

Longer wavelengths carry less energy.

UV has more energy than red light. Red light has more energy than infrared energy.

A nanometer is one billionth of a meter. UV, red, and infrared wavelengths are each only in the hundreds of nanometers wide.

Infrared has the longest wavelength at between 750 and 1,000 nanometers.

Red has slightly shorter wavelengths at 620 to 750 nm.

Ultraviolet has the shortest wavelengths of the three, between 10 and 380 nm.

Visible Light Spectrum
Visible Light Spectrum (source)
UV, Light, and Infrared Wavelengths*
Electromagnetic Field
750-1,000 nm (1 millimeter)
620-750 nm
590-620 nm
570-590 nm
495-570 nm
450-495 nm
380-450 nm
10-380 nm

(source, source)

Different sources cite different wavelengths because multiple factors affect the measurements. Indigo is not separate from blue. You will often see ultraviolet as high as 400 nm.

How Does Red Light Therapy Work?

Pulsaderm Handheld Red Light
Pulsaderm Handheld Red Light

Red light therapy is a photochemical process. The light gives the body photon energy. The body transforms that into chemical process that bring more energy to the treatment area.

So long as the user applies the right dosage, the body’s chromophore molecules accept the red light’s photon energy.

These chromophores then induce a molecular hydrogen and oxygen exchange.

That exchange stimulates the cell’s power production organelles known as mitochondria. The mitochondria transform adenosine diphosphate (ADP) to Adenosine Triphosphate (ATP).

The treatment area fills with energy, which promotes the body’s self-healing mechanisms.

Do Red Light Bulbs Heal the Body?

A red light bulb will not induce a therapeutic effect unless it emits the correct frequency and energy onto the correct body area for the therapeutic amount of time. While not out of the question, the chances are very low that even an array of red light bulbs will create a healing effect.

In fact, it is possible to fail getting a healing effect from a red light device designed to emit the right frequency and energy. If any of these variables is incorrect, the light will not deliver the right dose.

Red light alone does not heal the body. Healing also requires the correct time, the correct distance of the light from the body, a specific size for the treatment area, and the specific red light frequency for the job at hand.

These factors combine to form the Red Light Therapy’s dosage.

Distance: The dose increases when you are closer to the light, and decreases as you move away from the light.

Time: The dose increases with time, but then hits a peak therapeutic value. Any more time after that point either does not help, or can actually harm the area.

Wavelength: The red light therapeutic window includes wavelengths between 620 and 1,000 nm (billionths of a meter). There are wavelength sweet spots that have maximum therapeutic effect. A light bulb that emits red color will only emit frequencies in the sweet spot by chance, not by design.

Treatment area size: The joule is a unit of energy. Joules are measured in milliwatts. The light delivers a power density in milliwatts per square centimeter. If the milliwatts per square centimeter ratio is too low, the chromophores will not receive the photons. Too much power density will result in either no response or will actually inhibit rather than stimulate cellular activity. (source, source)

Are Home Red Light Devices as Good as Laser Devices?

Tendlight applies to wrist
Tendlight applies to wrist

Home red light devices can be just as effective as laser devices, so long as all the requirements for a therapeutic response are met (source).

Lasers produce coherent light waves. These waves peak and trough in sync with each other. They cannot interfere with each other, so they neither amplify nor cancel each other out.

LED waves are not coherent, so scientists theorized they would be less effective for healing.

As it turns out, laser light loses its coherence when applied to the body. A laser’s coherence properties are irrelevant to its therapeutic usefulness.

LED is just as effective as laser in improving wound healing duration.

Does Red Light Therapy Really Work?

Joovv Solo light box
Joovv Solo light box

Yes, red light therapy really works on a number of biological problems.

When the correct dosage is applied, red light induces a photochemical, energetic response. It induces the body to make more energy.

Because almost all cells have the ability to make energy, the therapy is healing for the entire body.

The correct dosage is essential for red light therapy to work.

These therapeutic results depend on applying the right amount of energy for the right amount of time.

You cannot just sit in front of a red light bulb to achieve therapeutic effects.

Area of Concern Red Light Therapeutic Effects
skin wounds Accelerates healing (source, source, source)
ischemic heart injury Improved recovery (source)
injured optic nerve Slows degeneration (source)
pediatric bone marrow transplant Prevent oral mucositis (digestive tract side effects) (source)
dermal abrasion Wound area reduction (source)
acne Decreased symptoms, especially in combination with blue light therapy (source)
carpal tunnel syndrome Reduces pain, increases motor function (source)
psoriasis inflammation In combination with blue light and curcumin, slows growth of disease (source)
hippocampus Increase brain-derived neurotropic factor (BDNF), decreases oxidative stress (source)
facial skin improved complexion, increased collagen (source)
hair stimulates hair growth (source)
muscles faster fatigue recovery (source)
memory both prevents and recovers from age-related memory loss (source)
eyes inhibits eye diseases caused when the eye cleans out bacteria (source) (source)
brain improves attention span in traumatic brain injury patients (source)
hip reduces pain after hip replacement (source)


Does Red Light Therapy Have Negative Side Effects?

Red Light Therapy has no known negative side effects. Improper use can cause minor problems.

There is no evidence if RLT is safe during pregnancy.

RLT might cause pain when applied to very dark skin, tattoos or the head.

It is possible to over stimulate the thyroid. Light manufacturers suggest avoiding pointing the device at the thyroid area without physician consultation.

(source) (source)  (source)  (source) (source) (source)

Laser light easily damages the eyes. Low energy red light devices are too weak to damage the eyes or the skin.

Used properly, red light therapy can improve macular degeneration.

Used improperly, red light can overwhelm the eye’s cones that absorb color light, creating a temporary light blindness effect.

Some evidence suggests that red light therapy promotes cell proliferation, which cancer patients should avoid (source). This is a small set of the evidence, and so this is still an open question. Temporary and mild red light side effects include:

  • headaches
  • fatigue
  • irritability
  • insomnia
  • illusions
  • abdominal bloating

About Caroline Bogart

Hello. My name is Caroline Bogart. I am a programmer, writer, and web developer. I build free websites for animal rescues. I was once featured in the Boston Globe. I am obssessed with all things EMF.

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