In recent years, LED light therapy has moved beyond the realm of skin rejuvenation and muscle recovery, capturing the attention of neuroscientists, clinicians, and wellness enthusiasts alike. Now, a growing body of research is exploring the potential of specific LED light therapy wavelengths to penetrate the skull and positively influence brain health.
However, not all light is the same, and the effectiveness of this approach depends on one key factor: whether the wavelengths can actually reach brain tissue.
Explore which wavelengths show the most promise and how they can help support treatment for a variety of brain-related health conditions with our experts at Rojo Light Therapy UK.
To appreciate how LED light therapy may benefit the brain, it’s essential to understand the physical challenge at hand: how light penetrates biological tissue, particularly the skull and surrounding layers.
When applying LED light therapy to the head, photons must pass through several layers:
Each of these layers reflects, scatters, or absorbs light to varying degrees.
Bone, in particular, can significantly decrease the reach for shorter wavelengths like blue or green light. That’s why only certain red and near-infrared wavelengths (typically 600–1100nm) have been shown to penetrate deeply enough to influence cortical structures.
Research shows that longer wavelengths in the near-infrared range (NIR), especially 800–1100nm, penetrate tissue more deeply than shorter red wavelengths (600–700nm).
One of the most cited studies on this topic, conducted by Wan et al. (1981), used cadaver skulls to determine that light around 810nm and 1064nm reached brain tissue at significantly higher rates than other wavelengths.
Another study conducted by Jagdeo et al. (2012) also demonstrated that NIR light could pass through human scalp and skull with measurable energy densities, suggesting the feasibility of transcranial photobiomodulation for clinical use.
The so-called "optical window," which ranges from approximately 600nm to 1100nm is where light penetration into the body is optimal. Outside this range, light is either absorbed too readily by melanin and blood (at shorter wavelengths) or by water (at longer infrared wavelengths), leaving little left to reach brain cells.
Wavelengths like 630nm and 660nm are commonly used in skin and surface-level therapy. They do show some penetration and can reach a few millimetres into soft tissue, but their effectiveness diminishes sharply when it comes to deeper structures like the cortex.
That said, when used in combination with near-infrared light, red wavelengths may still play a supportive role in modulating inflammation in the scalp and superficial vasculature.
Both animal studies and cadaver models have shown that wavelengths in this range can effectively penetrate the skull and reach cortical and even subcortical brain tissue.
The 810nm LED light therapy wavelength is the most commonly used in clinical studies involving neurodegeneration, traumatic brain injury (TBI), and cognitive decline. But apart from that, it is particularly noteworthy because it strikes a balance between strong tissue penetration and high mitochondrial absorption.
In one placebo-controlled study published in Neuropsychiatric Disease and Treatment showed that participants with mild traumatic brain injury experienced improvements in attention, executive function, and mood following a series of treatments with 810nm LED devices.
While the field is still evolving, clinical and preclinical studies suggest that transcranial photobiomodulation (tPBM) may support brain recovery, improve mental clarity, and slow the progression of neurodegenerative disease.
Let’s look at the brain-related conditions where LED light therapy has demonstrated the most potential.
Several early-stage clinical trials have shown that near-infrared light, particularly in the 810nm range, may help improve memory, attention, and executive function in people with MCI or early Alzheimer’s.
In one randomised, placebo-controlled trial in 2017, participants treated with near-infrared light (via transcranial and intranasal LED devices) over 12 weeks showed statistically significant improvements in cognition compared to the control group.Â
Improvements were particularly noticeable in word recall, clock drawing, and verbal fluency.
These results suggest that LED light therapy may help stimulate the healing activity of the mitochondria in the neurons most vulnerable to Alzheimer's-related damage.
Red and near-infrared light has also been used in patients with TBI and concussion, where symptoms often include memory loss, irritability, fatigue, and foggy thinking.
A case series by Naeser et al. in 2014 used 810nm LED therapy on veterans with chronic TBI. After a series of sessions, most participants reported improvements in working memory, verbal learning, and reduced PTSD symptoms.Â
Imaging studies also showed increased cerebral blood flow and connectivity in previously underactive regions of the brain.
Research has also shown that LED light therapy may have mood-regulating effects, particularly in those with treatment-resistant depression.
Researchers believe that the increased ATP production and modulation of inflammatory markers stimulated by the therapy can help restore activity in underperforming regions of the brain related to emotional regulation.
This has been demonstrated in a small 2018 study from Massachusetts General Hospital where researchers used 810nm light on the forehead in patients with major depressive disorder.
Results showed reduced depressive symptoms and improved sleep without adverse side effects.
From mild cognitive decline and brain fog to more complex neurological conditions like TBI and Parkinson’s, LED light therapy is an emerging tool in the broader toolkit of brain health strategies. And while it’s not a replacement for clinical care, its non-invasive nature, safety profile, and growing evidence base make it a promising complementary approach.
Discover more applications of LED light therapy in our blog, or check out our range of scientifically supported, high-performance LED light therapy devices for highly-effective at-home LED light therapy treatment benefits.
