Near-infrared light is becoming one of the most important technologies in non-invasive brain wellness.

It is being integrated into headbands, helmets, headphones and other cognitive wearables designed around mental performance, recovery, mood and healthy ageing. Unlike EEG systems, which measure electrical brain activity, these devices actively deliver light to the head.

The concept appears simple: position near-infrared emitters close to the scalp and direct the light towards the brain.

The engineering is far more complex.

Before light can reach cortical tissue, it must pass through skin, blood, muscle, connective tissue, hair and bone. Most of the applied energy is absorbed or scattered before reaching the intended target. The small portion that remains depends on the wavelength, treatment location, anatomy, device fit and optical design.

This is why an effective transcranial photobiomodulation device cannot be built by selecting a popular wavelength and placing LEDs inside a headset.

It must be developed around a clearly defined biological target.

What is near-infrared light?

Near-infrared, commonly abbreviated as NIR, sits just beyond visible red light in the electromagnetic spectrum.

Humans cannot see it, so an active NIR device may appear to emit little or no light. That does not mean the device is switched off. The energy is simply outside the range visible to the human eye.

Near-infrared light should not be confused with far-infrared heat therapy.

Far-infrared systems are generally designed to create a thermal effect. Photobiomodulation uses lower-intensity light to initiate photochemical and biological responses without intentionally heating the target tissue.

Within PBM research, commonly studied brain-focused wavelengths include approximately 750, 810, 850, 940 and 1064 nanometres. However, there is no universally superior wavelength for every neurological or cognitive application.

Each wavelength interacts differently with tissue, water, blood and cellular photoacceptors. Device developers therefore need to select a wavelength based on the intended target, delivery method and supporting evidence.

The broader difference between visible red and near-infrared light is explained in Red Light vs Near-Infrared (NIR): When to Use Which, and Why.

What is transcranial photobiomodulation?

Transcranial photobiomodulation, or tPBM, is the delivery of red or near-infrared light through the scalp towards the brain.

The device may target a specific region, such as the prefrontal cortex, or distribute light across a larger area of the head. Some systems also include intranasal emitters, although the route, target and contribution of intranasal delivery remain areas of ongoing investigation.

Depending on the intended application, tPBM may be delivered through:

• Headbands
• Helmets or caps
• Headphones
• Forehead applicators
• Handheld devices
• Multi-position wearable systems

The goal is not to heat the brain or electrically stimulate neurons. It is to provide controlled light energy that may influence cellular metabolism, circulation and signalling within illuminated tissue.

A wider introduction to these biological mechanisms is available in Photobiomodulation for Brain Health: How Light Supports Cognitive Function.

How does near-infrared light reach the brain?

When near-infrared light reaches the head, several things happen at once.

Some energy is reflected from the skin. Some is absorbed by blood, water, pigment and superficial tissue. Another portion is scattered in different directions. Only a relatively small amount continues through the skull towards brain tissue.

Human cadaver research has shown that 750 and 940 nm light can be detected several centimetres inside the head. However, transmission varied substantially between treatment locations and individuals. The researchers also found that soft tissue and blood-rich muscle layers can be as important as skull thickness in determining how much light passes through.

This has major implications for product development.

A device may deliver the same energy at the skin across the entire head, yet the amount reaching the brain may differ by location. The forehead, temples and top of the head do not have identical tissue structures.

User anatomy also varies.

Differences in skin, blood flow, subcutaneous tissue, skull geometry, hair and device pressure can all influence optical delivery. A fixed protocol will therefore not produce exactly the same intracranial exposure in every user.

Applied dose is not the same as brain dose

A common mistake is to treat the energy measured at the scalp as though the same amount reaches the brain.

It does not.

A device may apply a defined dose in Joules per cm² at the treatment surface. That figure describes incident energy at or near the skin. It does not tell the manufacturer exactly how much energy is absorbed by the cortex.

The pathway can be represented as several different measurements:

1. Optical output at the emitter
2. Irradiance at the device surface
3. Incident dose at the scalp
4. Energy transmitted through superficial tissue
5. Energy transmitted through the skull
6. Energy distributed within brain tissue

These values are not interchangeable.

For most commercial devices, direct measurement inside the living human brain is not practical. Manufacturers may therefore use a combination of optical testing, published tissue data, anatomical modelling and Monte Carlo simulations to estimate delivery.

Even then, the result remains an estimate rather than a universal value.

This distinction is explored more broadly in Understanding Joules per cm²: The Science of Optimal Light Therapy Dosing.

What happens when NIR reaches brain tissue?

Near-infrared light may interact with several cellular pathways.

Cytochrome c oxidase, an enzyme within the mitochondrial respiratory chain, is frequently discussed as an important photoacceptor. Mitochondria use oxygen and nutrients to produce adenosine triphosphate, or ATP, which supplies energy for cellular activity.

Neurons have particularly high energy requirements. They need continuous energy to maintain electrical gradients, release neurotransmitters and communicate with other cells.

By influencing mitochondrial and cellular signalling, tPBM may support:

• ATP production and cellular metabolism
• Nitric oxide signalling
• Local blood flow and oxygen delivery
• Redox balance
• Inflammatory signalling
• Cellular resilience and repair

The effect is more nuanced than simply “giving the brain more energy.” PBM can influence different pathways depending on the wavelength, dose, cellular state and treatment context.

For a deeper explanation of this foundation, read Photobiomodulation and Mitochondrial Health: The Foundation of PBM.

Why the prefrontal cortex receives so much attention

Many brain-focused PBM studies apply light to the forehead.

Part of the reason is practical. The forehead is relatively easy to access, and there is no hair blocking direct optical contact. It also provides a route towards the prefrontal cortex, which is involved in attention, working memory, decision-making and impulse control.

A 2026 randomized controlled study applied 1064 nm laser tPBM to the right prefrontal cortex. In adults with ADHD, active treatment was associated with improved performance on selected attention and impulse-control measures, alongside increased prefrontal oxygenation measured using fNIRS. The authors described the findings as promising but called for repeated-session studies and further validation.

That is an important distinction.

One positive study does not establish a universal treatment protocol. It shows that a specific wavelength, device, location, dose and study design produced measurable outcomes in a defined population.

An LED headset using a different wavelength or optical configuration cannot automatically claim the same results.

What does the current human evidence show?

Human tPBM research is expanding, but it remains a developing field.

Studies have investigated areas such as attention, memory, mood, traumatic brain injury, cognitive decline and neurological recovery. The protocols differ significantly, including the wavelengths used, treatment locations, session frequency, pulsing patterns and participant populations.

A 2025 proof-of-concept study used an 810 nm LED headset combined with an intranasal applicator in people with a history of repetitive head acceleration events. Improvements were reported across selected measures of attention, memory and cognition after several weeks. However, the study did not use the robust randomized, sham-controlled design required to establish treatment efficacy, and the authors explicitly called for stronger clinical trials.

More recent work has also explored 1064 nm tPBM and prefrontal oxygenation. These findings strengthen interest in the technology, but they do not yet identify one universal wavelength or dose for cognitive performance.

The responsible conclusion is therefore not that tPBM has been proven to enhance every aspect of brain function.

The evidence shows promising biological and cognitive signals that justify continued product development and clinical investigation.

Is 810 nm the best wavelength for the brain?

810 nm is one of the most frequently discussed wavelengths in transcranial PBM.

It is used in several research devices and sits within a range where tissue absorption and scattering may allow useful penetration. It is also widely available in LED components, making it practical for wearable product development.

But calling 810 nm the “best” or “gold standard” oversimplifies the science.

Other studies have used 850, 940 and 1064 nm. Human cadaver measurements have demonstrated transmission at 750 and 940 nm, while controlled human cognitive research has used 1064 nm.

The most suitable wavelength depends on:

• The intended tissue target
• Whether LEDs or lasers are used
• The treatment location
• Irradiance and total dose
• Optical beam characteristics
• Supporting scientific evidence
• Thermal and electrical constraints
• Intended claims

A product should therefore not select 810 nm simply because competing devices use it.

The choice needs to be supported by the complete treatment strategy.

LEDs versus lasers for transcranial PBM

Both LEDs and lasers can deliver near-infrared light.

Lasers produce a more directional and coherent beam. They can concentrate optical energy within a defined area and are frequently used in laboratory research.

LEDs spread light over a wider angle. They are generally easier to integrate into consumer wearables, can cover larger treatment areas and may reduce cost and design complexity.

Neither technology is automatically more effective.

The correct choice depends on the required beam profile, treatment area, device classification, safety controls and form factor.

An LED helmet may provide broad coverage across multiple head regions. A laser applicator may deliver more concentrated energy to a smaller target. The treatment protocol and evidence need to match the finished device.

Manufacturers must also account for optical uniformity. A headset can contain dozens of LEDs while still producing uneven exposure if emitter spacing, angle and distance are not engineered properly.

Hair is a major optical barrier

Hair can absorb, block and redirect near-infrared light before it reaches the scalp.

This creates one of the most practical challenges in brain-wearable design.

A device tested on an uncovered forehead may deliver consistent output. The same emitter placed over dense hair may provide far less energy to the skin.

Product developers can respond in several ways:

• Targeting low-hair or hair-free areas
• Designing emitters that move through or separate hair
• Using direct-contact optical elements
• Increasing coverage rather than only nominal power
• Including positioning guidance
• Detecting poor contact through sensors
• Developing protocols for specific treatment locations

Simply increasing output is not always the correct solution. Higher power can introduce heat, battery and safety challenges without solving inconsistent optical contact.

Fit affects treatment consistency

The physical fit of a tPBM device is part of its optical system.

When the product shifts, the angle and distance between the emitters and scalp change. This alters the amount and distribution of energy reaching the treatment surface.

A headset must therefore balance stability with comfort.

Too little pressure may create inconsistent contact. Too much pressure can make repeated sessions uncomfortable and reduce adherence. Different head sizes and shapes further complicate the design.

Adjustability should not only make the device fit more users. It should help maintain the intended optical position.

This is especially important for systems targeting a defined brain region. Moving an emitter a few centimetres can change the anatomical area being illuminated.

Continuous versus pulsed delivery

Near-infrared devices may deliver light continuously or in pulses.

Pulsed systems cycle the light on and off according to a selected frequency and duty cycle. This reduces the average power delivered over time and may influence thermal behaviour or biological signalling.

Some brain-focused devices use frequencies such as 10 Hz or 40 Hz. However, the existence of these protocols in research does not prove that a particular pulsing frequency is optimal for every application.

Pulsing changes several variables simultaneously:

• Average irradiance
• Peak irradiance
• Total energy
• Duty cycle
• Thermal load
• Timing of exposure

OEMs therefore need to report pulsed output accurately. Quoting only peak power can make the treatment appear stronger than the average energy actually delivered.

A pulsing protocol should be selected because it supports the intended use and evidence strategy, not simply because it creates another marketable mode.

Thermal management still matters

PBM is intended to create a photobiological rather than thermal effect.

The device itself can still become warm.

LEDs, drivers, processors, batteries and wireless components all generate heat. In a helmet or headband, these components sit close to the skin and may operate for several minutes at a time.

Thermal management may require heat-spreading materials, ventilation, temperature sensors, session limits and automatic shut-off controls.

The challenge is not only avoiding unsafe temperatures. The product must remain comfortable enough for repeated use.

A technically compliant device that feels hot, heavy or restrictive will struggle to achieve consistent user adherence.

The role of cognitive wearables and connected systems

The next generation of tPBM products may combine light delivery with sensing.

A connected brain wearable could use information from EEG, fNIRS, heart rate variability, sleep data or cognitive assessments to help schedule treatment or select between validated protocols.

This would move tPBM from fixed sessions towards more contextual use.

However, adaptive treatment creates additional responsibilities. The sensor must produce reliable data. The algorithm must interpret it correctly. The available intervention must remain within validated limits.

The opportunity is explored in How Light Therapy Is Powering the Next Generation of Cognitive Wearables.

For a wider introduction to the category, read What Are Cognitive Wearables? A Complete Guide for OEMs.

What OEMs need to define before development

A brain-focused PBM project should begin with the intended outcome, not the LED specification.

Before hardware development starts, the product team should define:

• The intended user
• The targeted treatment area
• The intended biological or cognitive objective
• Whether the product is wellness or medical
• The wavelength and delivery technology
• The applied dose and session duration
• The expected frequency of use
• How fit and positioning will be controlled
• Which claims the evidence can support

These decisions influence the optical system, electronics, mechanical design, software and regulatory pathway.

They also prevent a common development failure: building an impressive prototype first and trying to define its purpose afterwards.

Evidence must match the finished device

General research into tPBM can help establish scientific plausibility.

It does not automatically validate a commercial product.

The final device has its own emitter layout, wavelength tolerance, irradiance, pulse settings, form factor, treatment location and software. Even small changes can affect delivery.

A product claiming a medical or therapeutic outcome may therefore require device-specific performance data and clinical evidence.

Claims should remain proportionate to what has actually been tested. Clinical Evidence and Claims: What Light Therapy Brands Need to Know explains why evidence, intended use and product development need to remain aligned.

Conclusion

Near-infrared light creates a promising route for non-invasive interaction with the brain.

A portion of the applied energy can pass through the scalp and skull and reach cortical tissue. Once there, it may influence mitochondrial activity, circulation and cellular signalling. Human research has reported encouraging results across selected cognitive and neurological applications, but protocols remain varied and further controlled studies are still needed.

For OEMs, the real challenge is not selecting a fashionable wavelength.

It is controlling how the light is delivered.

Wavelength, dose, treatment location, hair, anatomy, fit, heat and user behaviour all influence the final result. The strongest products bring these variables together in one coherent system built around a defined biological objective.

At Light Tree Technology, we help brands develop advanced transcranial and wearable photobiomodulation devices from early research through optical engineering, prototyping, regulatory preparation and scalable production.

Looking to develop a near-infrared brain wearable?

Build the optical system, treatment protocol and product experience around the intended outcome from the beginning.

Start your project with Light Tree Technology.

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