What Is Photobiomodulation? The Science Behind Red And Near-Infrared Light Therapy

Photobiomodulation (PBM) is the clinical term for red and near-infrared light therapy. Light in the red and near-infrared range, roughly 600 to 1,100nm, is absorbed by cells and stimulates mitochondria, increasing ATP production, helping regulate oxidative stress, and supporting tissue repair. Some devices also use amber light at 590nm. PBM was once called low-level laser therapy (LLLT). Both lasers and LEDs are used today.

The science behind it is well studied.

When this light reaches your cells, tiny structures called mitochondria absorb it. This boosts the energy your cells make, lowers inflammation, and speeds up repair. In other words, photobiomodulation therapy gives your cells a little extra fuel to do their jobs better.

This article explains what PBM is, how it works step by step, and what the research actually shows. You will also learn how to tell a real treatment device from a gadget that only looks the part.

Photobiomodulation Is the Clinical Term You Need to Know

Photobiomodulation is simply the scientific name for red and near-infrared light therapy. The word breaks down into three easy parts. "Photo" means light, "bio" means life, and "modulation" means to change or adjust. Put together, it means using light to gently adjust how living cells behave.

The Name Comes From Older Research

The term photobiomodulation grew out of an older field once called Low-Level Laser Therapy, or LLLT. For years, researchers used that name because early devices relied on lasers. But as the science matured, the old name no longer fit every device.

In September 2014, a joint nomenclature consensus between the North American Association for Photobiomodulation Therapy (NAALT) and the World Association for Photobiomodulation Therapy (WALT) agreed on "photobiomodulation" as the standard term. The consensus was published in 2015, and the term was added to MeSH, the National Library of Medicine's medical vocabulary, the same year. The name needed to cover both lasers and LEDs, since both can be effective at the right dose.

Why Does This Matter When You Shop?

Knowing this term helps you spot devices backed by real evidence. Many products claim to offer "red light therapy," but not all of them are equal. When you see that phrase, look for the deeper science of PBM and published clinical studies behind it.

For example, iRESTORE's hair growth devices hold FDA 510(k) clearance to promote hair growth in androgenetic alopecia, within specified Norwood-Hamilton, Ludwig, and Fitzpatrick ranges. A 510(k) clearance means the FDA reviewed the device and found it substantially equivalent to a legally marketed device for that specific use. A term on a box is easy to print. A clearance ties a device to a specific, reviewed use.

The Science of How Photobiomodulation Works

Photobiomodulation works by turning light into cellular energy through four simple steps. The whole process happens inside your cells. PBM is not a heat-based therapy, though higher-powered panels can feel warm at close range. 

Let's walk through each step in plain language.

Step 1: Light Enters Your Skin

First, light has to get past your skin to reach your cells. Different wavelengths travel to different depths. Red light (roughly 600 to 700nm) is mostly absorbed in the outer layers of the skin, which makes it well suited to skin concerns. Near-infrared light (roughly 700 to 1,100nm) travels further, into tissue beneath the skin. Exact depth depends on wavelength, power, and the individual. 

The 810 to 850nm range is generally considered the deepest-penetrating part of what researchers call the "optical window," and 850nm is widely studied for muscles and joints. 940nm and 1,060nm are also used for deeper tissue, though they are less studied than 810 to 850nm. Some data suggest wavelengths around 1064nm penetrate well, but the evidence is mixed.

Step 2: Your Cells Absorb the Light

Next, a special protein inside your cells catches the light. Its name is cytochrome c oxidase, or CCO for short. It sits inside the mitochondria, the part of the cell that makes energy.

CCO is the leading explanation for how cells absorb this light. It contains copper and iron centers that absorb red and near-infrared photons, with absorption peaks around 620 to 680nm and 760 to 830nm. It is not the only proposed mechanism. Researchers have also proposed other light absorbers, such as water, light-gated ion channels, and light-sensitive proteins called opsins, especially at longer wavelengths.

Step 3: Your Cells Make More Energy

Then, something useful happens. Once CCO absorbs the light, it speeds up the cell's energy production line. The result is more ATP, the fuel your cells run on.

More ATP means more energy for healing, growth, and calming inflammation. Research led by Michael Hamblin helped explain this core mechanism in detail. Think of ATP like charging a phone battery. A fuller battery lets the cell do more work.

Our guide on how red light therapy panels work breaks down this cellular process in more detail.

Step 4: Helpful Chain Reactions Begin

Finally, a few smaller effects kick in. The light triggers the release of nitric oxide, which widens blood vessels and improves blood flow. It also fine-tunes other cellular signals involved in repair and inflammation.

These secondary effects explain why PBM helps with so many different issues. Here is the key idea to remember: photobiomodulation does not force your cells to do anything new. It simply gives them more energy to do what they are already built to do.

What Wavelengths Are Used in Photobiomodulation?

The wavelengths used in photobiomodulation usually range from roughly 600 to 1,100nm, and each one targets a different depth. Some devices also include amber light at 590nm. Shorter red wavelengths stay near the surface. Longer near-infrared wavelengths travel further into tissue. The right wavelength depends on your goal.

Here is a simple breakdown of commonly used wavelengths:

In general, longer wavelengths travel further, up to around 850nm. Beyond that, water absorption rises, so depth gains are less certain. That is why a skin device and a body device often use different wavelengths. Many devices combine two or more wavelengths to cover several depths at once.

What Does the Research Show?

Research strongly supports photobiomodulation for several specific applications, while others are still being studied. PBM is not one of those trends with no science behind it. In fact, thousands of peer-reviewed studies on PBM are now indexed on PubMed, the largest medical research database in the world. Still, the evidence is stronger for some uses than others.

Where the Evidence Is Strongest

The strongest evidence supports PBM for preventing oral mucositis, painful mouth sores caused by cancer treatment. It is backed by clinical practice guidelines from MASCC/ISOO, the leading international cancer supportive care societies.

Pain relief is another well-supported area. Reviews of randomized trials show PBM can ease musculoskeletal pain. For hair, the evidence supports FDA-cleared devices, including iRESTORE's hair growth devices, that promote hair growth in androgenetic alopecia.

Where the Evidence Is Strong and Growing

Other uses have good support that continues to develop. Skin rejuvenation is a clear example. Studies show red light can support collagen and improve skin texture, which is why iRESTORE's skin devices build on this research.

Wound healing has a long research history, including NASA-funded studies on LED light in the early 2000s, though results vary by wound type and study design.

In eye health, the Valeda Light Delivery System received FDA De Novo marketing authorization for dry age-related macular degeneration (AMD) in November 2024, following the LIGHTSITE III trial. This is a prescription device used in eye clinics and is unrelated to iRESTORE products.

Photobiomodulation vs Red Light Therapy: Is There a Difference?

There is no real difference between photobiomodulation and red light therapy in everyday use. The two terms describe the same thing. "Red light therapy" is the friendly name you see on product boxes. "Photobiomodulation" is the term used in scientific research papers.

That said, there is one small technical point worth knowing. Photobiomodulation covers both visible red light and near-infrared light. The phrase "red light therapy" can sometimes suggest only red light. So PBM is the slightly broader and more accurate term.

You may also still see the older term LLLT, short for Low-Level Laser Therapy. It described laser-only devices from an earlier era. The name changed to reflect that both lasers and LEDs are used. At the right dose, both can be effective. For more on this, see our breakdown of laser vs LED for hair growth.

Photobiomodulation at Home: What to Look For in a Device

A good home photobiomodulation device comes down to three things: the right wavelengths, enough power, and proof that it works. Many products look the same on the outside. But the details under the hood decide whether you get real results or just a warm glow. Here is what to check before you buy.

The Three Factors That Decide If a Device Works

Three things matter: the right wavelengths, the right dose, and a regulatory status that matches what the device claims to do. Let's break down each factor in plain terms.

First, check the wavelength. The most studied ranges are around 630 to 660nm for red and 810 to 850nm for near-infrared. Other wavelengths, such as amber (590nm), 940nm, and 1,060nm, are used for specific goals but have less research behind them.

Second, check the dose. Irradiance, measured in mW/cm², tells you how much light reaches your skin per second. Clinical studies use a wide range of irradiances depending on the target and the device. The iRESTORE Apex Pro 1500 and Apex Elite 2160 deliver 200 mW/cm² at 15cm (about 6 inches).

Irradiance is only part of the picture. Total dose, measured in joules per square centimeter (J/cm²), depends on irradiance and session time together. PBM follows a biphasic dose response: too little light does little, and too much can reduce the benefit. More is not always better. Follow the session time and distance recommended for your device.

Third, check that the device's regulatory status matches its claims. Some devices are FDA 510(k) cleared, meaning the FDA found them substantially equivalent to a legally marketed device for a specific use. Others are FDA-registered under a 510(k)-exempt classification, meaning the FDA does not require a 510(k) review for that device type, and its claims must stay within that classification. 

Neither label is a guarantee of results. What matters is that the claim on the box matches the status behind it.

What iRESTORE's Devices Deliver?

We match each device's wavelengths, power, and regulatory status to a specific job.

• iRESTORE Apex Elite 2160 and Apex Pro 1500: Eight wavelengths (590, 630, 660, 810, 830, 850, 940, and 1,060nm) at 200 mW/cm² at 15cm. FDA-registered, Class II, 510(k)-exempt, for the temporary relief of minor muscle and joint pain and stiffness, and a temporary increase in local blood circulation.

• iRESTORE Sculpt LED Belt: 630nm, 850nm, and 940nm. FDA 510(k) cleared for non-invasive body circumference reduction.

• iRESTORE Elite: 300 lasers and 200 LEDs, using 625nm, 655nm, and 680nm. FDA 510(k) cleared to promote hair growth in androgenetic alopecia, within specified Norwood-Hamilton, Ludwig, and Fitzpatrick ranges.

Key Takeaways

Photobiomodulation is simpler than its long name suggests. If you remember just a handful of points, remember these.

• Photobiomodulation (PBM) is the clinical name for red and near-infrared light therapy. The terms mean the same thing.

• The main action happens in your mitochondria. A protein called cytochrome c oxidase absorbs the light and helps your cells make more ATP, their fuel.

• Wavelength affects depth. PBM uses roughly 600 to 1100nm. Red light targets the skin's outer layers. Near-infrared, especially 810 to 850nm, travels further into tissue.

• The science is real and growing. The strongest evidence supports oral mucositis prevention, musculoskeletal pain, and FDA-cleared hair growth devices.

• Match the claim to the status. Check whether a device is FDA-cleared or FDA-registered, and that its claims fit that status.

• PBM is not a heat-based therapy. It works through light absorbed by cells, which sets it apart from infrared saunas, though powerful panels can feel warm.

Conclusion

Photobiomodulation may sound like a complicated lab term, but the idea behind it is simple. Specific colors of light reach your cells, and they convert that light into energy. With more energy, cells are better supported in doing the repair work they already do.

What makes PBM worth your attention is the science behind it. This is not a passing wellness fad. Decades of research, from early NASA wound studies to recent clinical trials, give it a real foundation. The honest takeaway is that the evidence is strong for some uses, growing for others, and still early for a few. Knowing the difference helps you set fair expectations.

When you shop, let the facts guide you instead of the marketing. Check the wavelength, ask about the dose, and confirm the device's regulatory status matches what it claims to do. With that knowledge, you can choose with confidence and skip the gadgets that only look the part.

Frequently Asked Questions

What is photobiomodulation in simple terms?

Photobiomodulation is the use of red and near-infrared light to wake up your cells. The light reaches tiny structures called mitochondria, which then make more energy. With that extra energy, your cells are better supported in their normal repair and recovery processes. It's light used as a gentle tool to help your body do work it's already built to do.

What's the difference between photobiomodulation and red light therapy?

Nothing functionally. "Red light therapy" is the consumer-facing name on product boxes. "Photobiomodulation" is the term used in research and the medical literature, and has been a MeSH term since 2015. The only nuance: photobiomodulation explicitly covers both red and near-infrared wavelengths, while "red light" can sound like it's red-only.

What does cytochrome c oxidase have to do with red light therapy?

Cytochrome c oxidase (CCO) is a protein inside your mitochondria and the leading explanation for how cells absorb red and near-infrared light. Its absorption peaks sit around 620 to 680nm and 760 to 830nm, and it is not a strong absorber at longer wavelengths like 1,060nm. Once CCO absorbs the light, it supports ATP production, the fuel your cells run on. Other light absorbers have also been proposed, so CCO is considered the primary pathway, not the only one.

How long does it take to see results from photobiomodulation?

It depends on the goal and the device. For skin, we recommend consistent use for at least 8 to 12 weeks. For iRESTORE hair growth devices, most users see visible results in 3 to 6 months of consistent use. Individual results vary.

Is photobiomodulation FDA-approved or just FDA-registered?

"FDA-approved" applies to drugs and high-risk devices, not PBM devices. PBM devices are typically either FDA 510(k) cleared or FDA-registered. An FDA-registered, 510(k)-exempt device belongs to a classification the FDA does not require to go through 510(k) review, and its claims must stay within that classification. Always check that a product's claims match its status.

Does light color (red vs blue vs green) matter for photobiomodulation, or just wavelength?

Wavelength is what matters, not the color name. Red and near-infrared light (roughly 600 to 1,100nm) are used for PBM, with cytochrome c oxidase absorbing most strongly around 620 to 680nm and 760 to 830nm. Blue light (around 405 to 420nm) works through a different mechanism, targeting acne-causing bacteria, and penetrates less deeply. Green and other visible wavelengths are less studied for PBM.

Disclaimer: The iRESTORE blog is for informational purposes only and is not intended to replace professional medical advice or treatment. Please do not ignore professional guidance because of information you’ve read here. If you have concerns about your hair, skin, pain, or overall health, we encourage you to consult a qualified healthcare professional.