NIR

NIR (near-infrared light) is an invisible part of the light spectrum with wavelengths of 800 to 1,000 nm that penetrates deeply into muscles, joints, and organs and stimulates mitochondria to produce more energy.

NIR is an abbreviation of the English term Near Infrared, meaning near-infrared light. It is electromagnetic radiation with wavelengths in the range of 800 to 1,000 nm, located just beyond visible red light. The human eye cannot perceive it, but for mitochondria in cells it is biologically as active as red light-  and in many ways even more effective, as it penetrates much deeper into tissues.

NIR light is an integral part of photobiomodulation and red and infrared light therapy. All Mitochondriak® devices combine red spectrum (630 to 670 nm) with NIR spectrum (810 and 850 nm), covering both superficial and deep tissues within a single therapy.

Why NIR is important and how it differs from red light

Red light and NIR light act through the same mechanism-the activation of the enzyme Cytochrome C oxidase (CCO) in mitochondria. The key difference lies in the depth of tissue penetration. [R]

Red light (for example 633 nm) penetrates to a depth of approximately 6.3 mm, which is sufficient for treating the skin, subcutaneous tissue, and superficial muscles. Deep red light (705 nm) penetrates to a depth of 7.5 mm and more, reaching muscles, joints, tendons, bone tissue, and internal organs. With higher device output and longer exposure times, the wavelength of 850 nm can penetrate almost the entire superficial muscle layer and reach deeper structures of the body.

For the average user, this has one practical implication: if you want to therapeutically affect superficial tissues (skin, scalp, wound healing), red light is sufficient. If you want to target deep tissues (joints, ligaments, muscles, spine, thyroid gland), the NIR component is essential.

Key NIR wavelengths and their biological effects

Not all NIR wavelengths act the same. From a therapeutic perspective, the most thoroughly studied are:

810 nm
The 810 nm wavelength is among those most strongly absorbed by Cytochrome C oxidase. Studies associate it with increased ATP production, reduced oxidative stress, and support for nerve tissue regeneration. It is used in protocols for muscle, joint, and neurological indications.

850 nm
The 850 nm wavelength has the greatest penetration depth among NIR wavelengths used in therapeutic devices. It penetrates deeper into muscle mass, joint capsules, and organs than 810 nm. This is why 850 nm is the standard choice for treating deep tissues, back pain, joint problems, and internal organs such as the thyroid gland. Near-infrared light can penetrate the entire body-this fact is used in practice, for example, in eye exposure (vision improvement) from the back of the head.

Mitochondriak® devices operate using the synergy of red and NIR light simultaneously. The red component (630 to 670 nm) covers superficial tissues, while the NIR component (810 and 850 nm) penetrates deeper-resulting in comprehensive therapy in a single step.

How NIR light works in cells

The mechanism of NIR is identical to that of photobiomodulation: photons of NIR light are absorbed by Cytochrome C oxidase in the mitochondrial respiratory chain. This absorption accelerates electron flow, increases the mitochondrial membrane potential, and thereby stimulates ATP synthase to produce more ATP.

In addition to its direct effect on mitochondria, NIR light also releases nitric oxide (NO) from hemoglobin and Cytochrome C oxidase. The released NO dilates blood vessels, increases blood flow, and improves the supply of oxygen and nutrients to tissues. Research has recorded an increase in blood flow of up to 200 percent for 20 minutes after NIR exposure. [R]

At the cellular level, NIR:

• increases ATP production in mitochondria
• reduces oxidative stress and inflammation
• supports collagen synthesis and tissue regeneration
• modulates the immune response
• releases nitric oxide and improves microcirculation

What NIR light is used for

Thanks to its depth of penetration, NIR light has a broader range of applications than red light alone. The most well-documented areas include:

Joints, muscles, and the musculoskeletal system
NIR light penetrates directly into joint capsules, tendons, and deep muscle tissue. Systematic reviews covering hundreds of clinical studies document significant pain reduction in knee osteoarthritis, back pain, tendinopathies, and postoperative conditions. [R]

Muscle recovery and athletic performance
NIR applied before or after physical activity reduces levels of creatine kinase and lactate in the blood, accelerates recovery, and extends time to exhaustion during repeated performance.

Thyroid gland
The thyroid gland lies at a shallow enough depth in the neck to be reached by NIR light. Clinical studies have reported improved thyroid function and reduced need for replacement therapy in patients with hypothyroidism after repeated NIR light therapy.

Cognitive function and the nervous system
Transcranial application of NIR light (directly on the scalp) is the subject of intensive research in relation to depression, Alzheimer’s and Parkinson’s disease, and traumatic brain injuries. A 2025 systematic review classifies NIR stimulation as an effective non-pharmacological method comparable to psychopharmacological treatment for several psychiatric conditions, with penetration depth reaching up to 40 mm. [R]

Skin and healing
While red light is more effective for surface skin treatment, NIR complements its effect in deeper dermal layers and supports healing of deeper wounds, scars, and inflammatory conditions.

Related terms

• Photobiomodulation - scientific term for red and NIR light therapy
• Red light (RED) - visible part of the spectrum (620 to 700 nm), partner to NIR for superficial tissue treatment
• ATP - cellular energy whose production is stimulated by NIR light via CCO
• Cytochrome C oxidase (CCO) - mitochondrial enzyme, primary photoreceptor for both NIR and red light
• Nitric oxide (NO) - signaling molecule released during NIR therapy, responsible for vasodilation and improved blood flow
• Mitochondria - target organelles of NIR light in every cell of the body
• Pulsing - device mode in which NIR light is delivered in pulses, enhancing certain biological effects
• LLLT (Low Level Laser Therapy) - an older term for low-power laser therapy, now included under photobiomodulation; it used the same NIR wavelengths

Frequently asked questions about NIR light

What does NIR mean?

NIR stands for Near Infrared, meaning near-infrared light. It is electromagnetic radiation with wavelengths of 800 to 1,000 nm, located just beyond the visible red spectrum. The human eye cannot perceive it, but it is biologically active and stimulates mitochondria similarly to visible red light, while penetrating much deeper into tissues.

What is the difference between red light and NIR?

Both types of light act through the same mechanism (activation of Cytochrome C oxidase in mitochondria), but differ in penetration depth. Red light (620 to 800 nm) primarily reaches the skin, subcutaneous tissue, and superficial muscles. NIR light (800 to 1,000 nm) penetrates deeper-into muscles, joints, tendons, bones, and internal organs. For comprehensive full-body therapy, both types are best used in combination.

Is NIR light dangerous?

No. NIR light in the range of 800 to 1,000 nm is safe and non-ionizing when properly dosed-it does not cause thermal damage and does not contain UV radiation. The Arndt–Schulz law applies: excessively high intensity or overly long exposure may be less effective, but not toxic. Mitochondriak® devices are designed to operate within a therapeutic window safe for home use.

Why can’t NIR light be seen?

The human eye is sensitive to light in the range of approximately 380 to 700 nm. NIR light (800 to 1,000 nm) lies beyond this range, which is why we cannot see it. Nevertheless, it is biologically active-the mitochondrial enzyme Cytochrome C oxidase absorbs it and triggers a cascade of energy and regenerative processes. Some cameras and sensors (for example on smartphones) detect NIR light as a faint reddish glow.

Which NIR wavelength is the most effective?

From a therapeutic perspective, the most studied wavelengths are 810 nm and 850 nm. The 810 nm wavelength shows strong absorption by Cytochrome C oxidase and is recommended for neurological and muscular applications. The 850 nm wavelength has greater penetration depth and is more suitable for joints, the thyroid gland, and deep internal tissues. Mitochondriak® devices include both wavelengths.

How long does NIR light therapy take?

Standard therapy lasts 10 to 20 minutes at a distance of 5 to 30 cm from the body. For deep tissues (joints, organs), it is advisable to be closer to the device and extend exposure to 15 to 30 minutes. The recommended frequency is 3 to 5 times per week. Exact parameters depend on the specific device and indication.

How is NIR different from regular infrared (thermal) radiation?

Near-infrared light (NIR, 800 to 1,000 nm) is a therapeutic spectrum that acts on mitochondria without significant thermal effect-low energy, but a strong biological signal. Mid and far infrared radiation (above 1,400 nm) acts primarily through heat, warming the tissue. Standard infrared heaters and sauna panels use far-infrared radiation—the biological mechanism is different and is not synonymous with photobiomodulation.

Summary

NIR (near-infrared light, 800 to 1,000 nm) is an invisible, biologically active part of the light spectrum that penetrates deeply into muscles, joints, organs, and nervous tissue. It activates Cytochrome C oxidase in mitochondria, increases ATP production, releases nitric oxide, and reduces inflammation. In combination with red light, it forms the basis of photobiomodulation and is part of every Mitochondriak® device.

Want to try NIR therapy at home? Explore our red and infrared light therapy devices or read more about how infrared light penetrates the entire body.

Scientific studies and sources

• NIR light in bone-related diseases - tissue penetration depth at 705 nm: 7.5 mm. PMC. 2020. PMC7546009
• Henderson TA, Morries LD. Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain? Neuropsychiatric Disease and Treatment. 2015. PMC4552256
• Near-Infrared Stimulation in Psychiatry Disorders — systematic review, NIR penetration up to 40 mm depth. MDPI Brain Sciences. 2025. doi.org/10.3390/brainsci
• Umbrella review of RCT meta-analyses on photobiomodulation - pain, inflammation, joints. Systematic Reviews. 2025. PMC12326686