iMediSync uses 850 nm near-infrared light for transcranial photobiomodulation (tPBM) in its iSyncWave and iSyncMe systems. But why 850 nm? And how does it compare with the increasingly marketed 1064–1070 nm range?

The answer is more nuanced than simply assuming that a longer wavelength penetrates deeper and is therefore better.

Research suggests that 850 nm and 1064–1070 nm represent two somewhat different approaches to brain photobiomodulation. Longer wavelengths may benefit from reduced optical scattering, while 850 nm sits within a particularly important biological range for mitochondrial photobiomodulation and cytochrome-c oxidase absorption.

Just as importantly, wavelength is only one part of a brain-PBM protocol. Where the light is delivered, how much energy reaches the tissue, whether the light is pulsed, the pulse frequency, and how treatment targets are selected may all influence the biological response.

Key Takeaways: 850 nm vs. 1070 nm

850 nm is within one of the most established biological windows for photobiomodulation. Reviews of PBM mechanisms identify approximately 800–850 nm as an important near-infrared absorption region for mitochondrial cytochrome-c oxidase (CCO), a key component of cellular respiration.[1,2]

1070 nm scatters less, but that does not automatically mean more useful energy reaches the brain. Longer wavelengths around 1064–1070 nm benefit from lower tissue scattering, but water absorption also increases at longer near-infrared wavelengths. Computational studies therefore do not agree that 1064–1070 nm universally produces greater cortical energy deposition.[3–5]

850 nm performs competitively in brain dosimetry models. A Harvard/Massachusetts General Hospital-associated Monte Carlo study comparing 670, 810, 850, 980 and 1064 nm found 810 nm produced the greatest modeled brain deposition, with 1064 and 850 nm following closely behind.[3]

850 nm has direct human brain evidence. Controlled human studies using 850 nm have reported measurable changes in EEG activity, attention and cognitive performance.[6–8]

There is now published research using iMediSync's own 850 nm technology. A 2026 Neurotherapeutics study used iSyncMe to deliver 850 nm PBM across 19 International 10–20 locations with frequency-specific stimulation during home use.[9]

The practical conclusion is not that 1070 nm "doesn't work." Research clearly indicates that it can produce biological effects.

The more important point is:

There is currently no compelling evidence showing that 1070 nm is inherently superior to 850 nm for brain photobiomodulation.

And there are several reasons why 850 nm remains particularly compelling.

Why Is 850 nm Used for Photobiomodulation?

Photobiomodulation uses red or near-infrared light to influence biological processes rather than simply heating tissue.

One of the leading proposed mechanisms involves cytochrome-c oxidase, or CCO, an enzyme within mitochondrial complex IV that plays a critical role in cellular respiration.

CCO contains several chromophores capable of absorbing light. Reviews of the photobiomodulation literature identify an important near-infrared absorption region around 800–850 nm. One major review describes light between approximately 600 and 850 nm as acting primarily through the mitochondrial electron transport chain and identifies an oxidized CCO absorption band in approximately the 800–870 nm region.[1]

Another review of PBM parameters notes that a substantial portion of optical absorption between 800 and 850 nm has been attributed to CCO under experimental conditions.[10]

This makes 850 nm biologically interesting for reasons beyond its ability to simply travel through tissue.

What Happens After Mitochondria Absorb Near-Infrared Light?

The classical PBM model proposes that absorption of near-infrared photons can influence mitochondrial respiration.

Proposed downstream effects include:

• changes in cytochrome-c oxidase activity,

• modulation of mitochondrial membrane potential,

• changes in oxygen consumption,

• altered ATP production,

• transient reactive oxygen species signaling,

• nitric oxide-related signaling,

• and downstream cellular signaling pathways.

The important distinction is that 850 nm is positioned directly within the wavelength range where this mitochondrial mechanism has been most extensively studied.[1,2]

Does 1070 nm Penetrate Deeper Than 850 nm?

This question sounds simple.

It isn't.

Longer wavelengths generally experience less optical scattering in biological tissue. That gives 1064–1070 nm a legitimate theoretical advantage and is one reason these wavelengths have attracted attention for transcranial PBM.

But scattering is only one source of attenuation.

Light traveling from an LED or laser toward the cortex must pass through skin, connective tissue, skull, cerebrospinal fluid and other tissues. Along the way, photons can be scattered or absorbed.

And water absorption becomes increasingly important as wavelength moves above the traditional 800–850 nm PBM region.

A 2026 systematic review of CNS photobiomodulation specifically challenged the assumption that 1064 nm automatically possesses a major penetration advantage. The authors noted that water absorption at 1064 nm is substantially higher than around 808 nm and argued that this can offset part of the benefit gained from reduced scattering.[11]

This is why simulations of brain PBM have produced conflicting answers.

A comprehensive 2024 systematic review of 97 brain-PBM studies highlighted this disagreement directly: some modeling studies have favored approximately 1064 nm because of lower scattering, while others have found shorter NIR wavelengths capable of producing greater or broader cerebral photon delivery.[5]

What Happens When 850 nm Is Included in the Same Model?

This is particularly relevant.

Researchers associated with Massachusetts General Hospital, Harvard Medical School and Northeastern University modeled 670, 810, 850, 980 and 1064 nm using Monte Carlo simulations.

They found:

1. 810 nm generally produced the greatest modeled brain energy deposition.

2. 1064 nm and 850 nm followed closely behind.

3. 670 and 980 nm generally produced lower deposition.

The study found that 850 nm typically deposited somewhat less energy than 1064 nm in certain targets, but the result depended strongly on anatomy and the amount of cerebrospinal fluid between the light source and target. When little CSF separated the emitter and target, 850 nm approached the performance of 810 nm.[3]

A later study using 18 MRI-based head models spanning childhood through older age produced a similar picture: 810 nm generated the highest modeled energy deposition, followed by 1064 and 850 nm, while both generally outperformed 670 and 980 nm.[4]

That is considerably different from saying:

"1070 nm penetrates deeper, therefore 1070 nm is better."

The actual optical picture depends on wavelength, anatomy, tissue composition, emitter position and device parameters.

850 nm vs. 1070 nm: Different Biological Tradeoffs

The most useful comparison may not be which wavelength can theoretically travel the farthest.

It may be what happens to those photons once they arrive.

A major brain-PBM review summarizes the distinction clearly: CCO absorption is stronger around 800–850 nm than at 1064–1072 nm, while the reduced scattering of longer wavelengths may allow photons to travel farther through some tissues.[1]

That creates a genuine tradeoff.

850 nm

Strong interaction with the traditional mitochondrial PBM absorption region, combined with useful penetration into cranial tissue.

1070 nm

Reduced scattering that may improve propagation through some tissues, but weaker CCO absorption and greater contribution from other chromophores and mechanisms.

Neither characteristic alone determines the biological outcome.

Does 850 nm Actually Affect the Human Brain?

Yes. This is where the case for 850 nm becomes much stronger than an optical-model discussion alone would suggest.

850 nm PBM and EEG

Jahan and colleagues studied 30 healthy adults using 850 nm LED photobiomodulation over the right prefrontal cortex.

The researchers recorded 19-channel EEG before and after active or sham stimulation and administered an attention task.

The active PBM condition produced a significant improvement in reaction time, and the researchers observed changes in brain electrophysiological activity.[6]

That matters because it demonstrates that 850 nm isn't simply capable of crossing tissue in a computer model.

It can produce measurable changes in human cortical electrophysiology.

850 nm PBM and Mild Cognitive Impairment

Another randomized controlled trial studied 42 older women with mild cognitive impairment.

Participants received either active or sham treatment, with active treatment consisting of five sessions of 850 nm PBM over the right frontal pole.

Researchers reported significant treatment-by-time effects in:

• MMSE scores,

• reaction time,

• percentage of correct responses,

• and attention efficiency measures.

The authors concluded that their 850 nm protocol positively affected cognitive and attentional performance.[7]

This doesn't establish that every 850 nm device will reproduce those results. PBM outcomes depend heavily on dose and protocol.

But it does establish something important:

850 nm has direct controlled human evidence supporting biological effects in the brain.

Pulsing Matters Too: 850 nm at 40 Hz and 100 Hz

Wavelength gets most of the attention in marketing.

But wavelength is only one parameter.

Tang and colleagues conducted a randomized sham-controlled study involving 56 healthy adults comparing continuous and pulsed photobiomodulation.

The study used 660 nm and 850 nm, with participants receiving:

• sham stimulation,

• continuous-wave PBM,

• 40 Hz pulsed PBM,

• or 100 Hz pulsed PBM.

Researchers collected 32-channel EEG and assessed attention, memory and subjective sleepiness.

Under certain conditions, pulsed PBM was associated with improvements in neurocognitive measures and changes in EEG activity, including increased gamma-band power during stimulation.[8]

That finding highlights an important point:

Two devices using the same wavelength are not necessarily delivering the same neuromodulatory intervention.

Pulse frequency, irradiance, exposure time, anatomical location and treatment schedule all matter.

Wavelength Alone Is Not a PBM Protocol

A 2024 systematic review screened more than 2,000 publications and ultimately evaluated 97 brain-photobiomodulation studies.

The authors found substantial variation in:

• wavelength,

• device design,

• stimulation location,

• irradiance,

• energy density,

• continuous versus pulsed operation,

• treatment duration,

• and treatment schedule.[5]

That is important when comparing commercial PBM devices.

Simply asking whether a headset uses 850 nm or 1070 nm overlooks much of what determines the delivered intervention.

Consider two hypothetical devices.

One could use 1070 nm but deliver one fixed stimulation pattern across the entire scalp.

Another could use 850 nm while controlling:

• which cortical locations receive light,

• the pulse frequency delivered to those locations,

• treatment duration,

• and protocol selection based on EEG information.

Those are fundamentally different approaches to brain stimulation.

The iMediSync Approach: Measure First, Then Target

This is where iMediSync approaches photobiomodulation differently.

iSyncWave and iSyncMe integrate EEG measurement with 850 nm near-infrared photobiomodulation across the International 10–20 system.

Rather than treating the head as one uniform target, the system places PBM emitters alongside the same anatomical locations used for 19-channel EEG.

iSyncMe incorporates 19 850 nm LEDs, corresponding to the standard EEG locations, with programmable pulse frequencies from 1–45 Hz.

This creates the possibility of a workflow in which clinicians can:

Measure → Analyze → Target

1. Record EEG activity.

2. Analyze the EEG using quantitative EEG tools.

3. Identify relevant cortical regions and patterns.

4. Design PBM stimulation around selected regions and pulse frequencies.

This is fundamentally different from choosing a wavelength and illuminating the entire head using one fixed protocol.

850 nm iSyncMe PBM Has Now Been Studied in Humans

In 2026, researchers from Yonsei University College of Medicine, Samsung Medical Center, Seoul National University and other institutions published a randomized study in Neurotherapeutics evaluating transcranial PBM and transauricular vagus nerve stimulation in 60 participants with subclinical alcohol use.

The tPBM condition used iSyncMe.

The device delivered 850 nm near-infrared light across 19 International 10–20 locations.

Instead of using one uniform stimulation frequency, the protocol consisted of three sequential phases:

• 10 Hz stimulation over parietal and occipital regions,

• 15 Hz whole-brain stimulation,

• 18 Hz frontal stimulation.

Participants self-administered treatment at home five times per week for five weeks.[9]

The researchers reported significant reductions in craving and alcohol-use measures in the tPBM condition compared with the taVNS-only condition. The study was a randomized comparative trial rather than a sham-controlled PBM trial, so the findings should be interpreted within that design.[9]

For iMediSync, the study is particularly important because it demonstrates published human research using the actual architecture behind the system:

850 nm + 19 cortical locations + frequency-specific stimulation + home use.

What About Research Supporting 1064–1070 nm?

There is legitimate research supporting 1064 and 1070 nm.

Human studies have reported changes in cerebral oxygenation, mitochondrial redox state, EEG activity and cognitive performance following stimulation in this wavelength range.

Longer wavelengths also scatter less through biological tissues, providing a plausible physical rationale for deeper propagation.

One particularly interesting human experiment compared 800 nm, 850 nm and 1064 nm laser PBM on the forearm and measured oxygenated hemoglobin and oxidized CCO.

All three wavelengths produced significant biological changes. In that experiment, the 1064 nm condition produced effects that persisted longer.[12]

But there is an important limitation when using that experiment to argue for 1070 nm brain superiority:

the experiment was conducted on the human forearm, not through the human scalp and skull into the brain.

It therefore demonstrates biological activity at 1064 nm, but does not establish superiority over 850 nm for transcranial brain PBM.

Is 1070 nm Better Because It Is a Longer Wavelength?

Not necessarily.

This is one of the most common oversimplifications in discussions of PBM.

Longer wavelength does generally reduce scattering.

But total brain delivery depends on both scattering and absorption, along with anatomy and the optical properties of each tissue encountered.

Research models produce different conclusions depending on their assumptions.

The 2024 comprehensive review of brain-PBM devices explicitly noted that simulations disagree on whether 1064 nm or shorter NIR wavelengths provide superior penetration.[5]

A 2026 systematic review went further, arguing that the increasing absorption of longer NIR wavelengths by water means that the commonly assumed penetration advantage of 1064 nm may be substantially smaller than often presented.[11]

Meanwhile, studies directly modeling 850 nm consistently place it among the better-performing wavelengths for cerebral energy deposition.[3,4]

So the scientifically defensible conclusion is:

1070 nm has a scattering advantage. That does not establish a universal brain-delivery advantage.

Why 850 nm Remains a Compelling Wavelength for Brain PBM

Taken together, several features make 850 nm particularly attractive.

1. It falls within a major mitochondrial PBM absorption region.

The CCO-centered mechanism of PBM is particularly well established around 800–850 nm.[1,2]

2. It still provides substantial transcranial penetration.

Monte Carlo brain models place 850 nm among the strongest wavelengths tested for cerebral energy deposition.[3,4]

3. It avoids some of the increased water absorption encountered at longer NIR wavelengths.

This can partially offset the reduced scattering advantage associated with 1064–1070 nm.[11]

4. It has direct human EEG evidence.

850 nm stimulation has been associated with measurable changes in electrophysiological activity in controlled human studies.[6,8]

5. It has randomized human cognitive research.

Studies have reported changes in attention and cognitive outcomes following 850 nm transcranial stimulation.[6–8]

6. It can be combined with frequency-specific stimulation.

Pulsed 850 nm research suggests that stimulation frequency may itself influence neurophysiological effects.[8]

7. It now has published research using iMediSync technology.

The 2026 Neurotherapeutics study provides a direct example of 850 nm being delivered using iSyncMe across 19 cortical locations in a structured, frequency-specific protocol.[9]

850 nm vs. 1070 nm: Which Is Better for Brain Photobiomodulation?

At this point, the scientific literature does not justify declaring one wavelength universally superior for every PBM application.

1070 nm has a legitimate advantage in reduced optical scattering and has demonstrated biological effects in human research.

But the idea that 1070 nm must therefore be the better brain-PBM wavelength is not supported by the totality of the evidence.

850 nm offers a particularly compelling combination of:

strong mitochondrial relevance + favorable brain dosimetry + direct human EEG evidence + controlled cognitive research + compatibility with pulsed, frequency-specific neuromodulation.

For iMediSync, wavelength is also only the beginning.

The larger concept is to combine 850 nm near-infrared PBM with 19-channel EEG/qEEG information, anatomical targeting through the International 10–20 system, and programmable stimulation frequencies.

Instead of asking only:

"Which wavelength goes deepest?"

A more useful question may be:

What wavelength, dose, location and stimulation pattern are being delivered—and why were those parameters selected for this brain?

That is where brain photobiomodulation is likely headed: away from one-size-fits-all illumination and toward measurable, targeted and individualized neuromodulation.

Frequently Asked Questions

Does 1070 nm penetrate deeper than 850 nm?

1070 nm generally experiences less optical scattering. However, longer wavelengths also encounter greater water absorption, and simulations of transcranial PBM do not consistently show that 1064–1070 nm delivers more useful energy to cortical targets. Studies that include 850 nm place it among the strongest wavelengths for modeled brain deposition.[3–5,11]

Does 850 nm reach the brain?

Modeling studies support transcranial delivery of 850 nm light, and human experiments have demonstrated measurable EEG and cognitive changes after 850 nm stimulation.[3,4,6–8]

Why is 850 nm important for mitochondria?

Cytochrome-c oxidase has important absorption features within approximately the 800–850 nm region. CCO-centered mitochondrial photobiology is therefore particularly well established in this wavelength range.[1,2,10]

Is 1070 nm ineffective?

No. Human and laboratory studies demonstrate biological effects from 1064–1070 nm PBM. The evidence simply does not establish that those wavelengths are universally superior to 850 nm for transcranial applications.

Does pulse frequency matter in photobiomodulation?

Potentially. A randomized sham-controlled human study comparing continuous and pulsed PBM found different neurocognitive and EEG responses under pulsed conditions, including protocols using 850 nm.[8]

What wavelength does iMediSync use?

iSyncWave and iSyncMe use 850 nm near-infrared LEDs integrated across 19 EEG locations. The systems support programmable PBM pulse frequencies, allowing stimulation protocols to be designed around specific regions and frequencies.

References

1. Salehpour F, Mahmoudi J, Kamari F, Sadigh-Eteghad S, Rasta SH, Hamblin MR. Brain Photobiomodulation Therapy: A Narrative Review. Molecular Neurobiology. 2018;55:6601–6636. DOI: 10.1007/s12035-017-0852-4.

2. Fernandes F, Oliveira S, Monteiro F, et al. Devices used for photobiomodulation of the brain: a comprehensive and systematic review. Journal of NeuroEngineering and Rehabilitation. 2024;21:53. DOI: 10.1186/s12984-024-01351-8.

3. Cassano P, Tran AP, Katnani H, et al. Selective photobiomodulation for emotion regulation: model-based dosimetry study. Neurophotonics. 2019;6(1):015004. DOI: 10.1117/1.NPh.6.1.015004.

4. Yuan Y, Cassano P, Pias M, Fang Q. Transcranial photobiomodulation with near-infrared light from childhood to elderliness: simulation of dosimetry. Neurophotonics. 2020;7(1):015009. DOI: 10.1117/1.NPh.7.1.015009.

5. Fernandes F, et al. Devices used for photobiomodulation of the brain—a comprehensive and systematic review. The review discusses conflicting simulation evidence concerning 810–850 nm and 1064 nm penetration and emphasizes the importance of device configuration and dosimetry. DOI: 10.1186/s12984-024-01351-8.

6. Jahan A, Nazari MA, Mahmoudi J, Salehpour F, Salimi MM. Transcranial near-infrared photobiomodulation could modulate brain electrophysiological features and attentional performance in healthy young adults. Lasers in Medical Science. 2019;34(6):1193–1200. DOI: 10.1007/s10103-018-02710-3.

7. Papi S, Allahverdipour H, Jahan A, Dianat I, Jafarabadi MA, Salimi MM. The effect of transcranial photobiomodulation on cognitive function and attentional performance of older women with mild cognitive impairment: a randomized controlled trial. Przegląd Menopauzalny. 2022;21(3):157–164. DOI: 10.5114/pm.2022.119794.

8. Tang L, Jiang H, Sun M, Liu M. Pulsed transcranial photobiomodulation generates distinct beneficial neurocognitive effects compared with continuous wave transcranial light. Lasers in Medical Science. 2023;38:203. DOI: 10.1007/s10103-023-03865-4.

9. Kwon M, Park M, Kim M, et al. The effectiveness of transcranial photobiomodulation therapy (tPBM) and transauricular vagus nerve stimulation (taVNS) on reducing alcohol craving. Neurotherapeutics. 2026;23(4):e00937. DOI: 10.1016/j.neurot.2026.e00937.

10. Review of light parameters and photobiomodulation efficacy: dive into complexity. Review discussing CCO absorption and the importance of wavelength-dependent PBM effects.

11. Cronshaw M, Parker S, Lynch E, Dixon W, Hing AK, Grootveld M. Photobiomodulation Therapy and Central Nervous System Disorders: A Systematic Review of Delivery Routes, Mechanisms, Parameters and Clinical Evidence. Photonics. 2026;13(5):488. DOI: 10.3390/photonics13050488.

12. Pruitt T, et al. Photobiomodulation at Different Wavelengths Boosts Mitochondrial Redox Metabolism and Hemoglobin Oxygenation: Lasers vs. Light-Emitting Diodes In Vivo. Metabolites. 2022;12(2):103. DOI: 10.3390/metabo12020103.

This article discusses emerging photobiomodulation research. In the United States, iMediSync's PBM functionality is not FDA-cleared for the diagnosis or treatment of disease.