Light Therapy Shows Promise for Long COVID Brain Fog in Rigorous Trial

TORONTO, ON – January 14, 2026

A rigorously designed clinical trial has provided a potential beacon of hope for the millions suffering from the cognitive dysfunction, or “brain fog,” associated with long COVID. The study, published today in The Lancet’s eClinicalMedicine, found that a non-invasive, home-based light therapy device significantly improved objective cognitive performance in adults under 45. These preliminary findings represent one of the first scientifically credible signals of an effective, scalable intervention for a debilitating condition that currently has no approved treatments.

Conducted in the U.S., the randomized, double-blind, sham-controlled trial investigated a form of near-infrared light stimulation known as intranasal and transcranial photobiomodulation (itPBM). The intervention was delivered using the Vielight Neuro RX Gamma, a device developed by Toronto-based medical technology company Vielight Inc., which also funded the study.

A Crippling Condition Meets a Novel Approach

For countless individuals, recovering from a COVID-19 infection is not the end of their ordeal. A significant percentage develop post-COVID-19 condition (PCC), or long COVID, with symptoms that can persist for months or years. Among the most common and disruptive of these is brain fog, a type of cognitive impairment that affects attention, memory, and executive function. It can derail careers, disrupt education, and severely diminish quality of life, leaving many feeling like strangers in their own minds.

The economic toll is staggering. Recent estimates from the Brookings Institution suggest that long COVID could be keeping up to 4 million Americans out of the workforce, costing the economy over $200 billion annually in lost wages. This massive unmet medical and societal need has left patients and clinicians scrambling for solutions, often relying on symptom management, coping strategies, or off-label use of medications with limited evidence.

“Long COVID brain fog doesn’t just affect individuals. It impacts families, employers, healthcare systems, and mental well-being,” said Dr. Lew Lim, founder of Vielight Inc. and corresponding author of the study. “Our objective was to rigorously evaluate whether a non-invasive, home-based intervention could produce objective signals of cognitive improvement, particularly in people still early in their working lives.”

Under the Light: A Study Built on Rigor

What sets this pilot study apart is its high-quality design, a standard often seen in pharmaceutical trials but less common for device-based interventions. The trial enrolled 43 adults with persistent cognitive symptoms and randomized them to receive either the active light therapy or a visually identical sham device for eight weeks. Crucially, the study was double-blind, meaning neither the participants nor the investigators knew who received the real treatment.

Instead of relying solely on subjective patient reports, the study’s primary goal was to measure objective changes in cognitive performance using a validated digital testing battery. The results were compelling: participants under the age of 45 who used the active device showed statistically significant improvements in their composite cognitive scores compared to those using the sham device. The most consistent gains were seen in tasks related to attention.

In the full study group, which included participants up to age 65, those receiving the active treatment still showed greater improvement than the sham group, though the difference did not reach the threshold for statistical significance. The therapy was well-tolerated, with high adherence to the at-home treatment schedule and no serious adverse events reported.

“From a neuroscience perspective, this study stands out for its rigorous sham-controlled design and use of objective cognitive endpoints,” commented Dr. Reza Zomorrodi, a neuroscientist and senior author affiliated with the Centre for Addiction and Mental Health (CAMH) and the University of Toronto. “While the findings are preliminary, the improvements observed, particularly in attention, are consistent with known mechanisms of network-level modulation and neuroplasticity.”

The Science of Photobiomodulation

Photobiomodulation (PBM) is not a new concept, but its application to brain health is a rapidly advancing frontier. The therapy uses low-level red or near-infrared light to stimulate cellular function. The photons are primarily absorbed by an enzyme within the mitochondria, the powerhouses of the cell, called cytochrome c oxidase. This process is believed to enhance energy (ATP) production, improve oxygen utilization, and increase cerebral blood flow.

By boosting brain metabolism and reducing inflammation, PBM may help support the brain's natural repair mechanisms. The Vielight Neuro RX Gamma device delivers this light both through the scalp (transcranially) and via a clip placed inside the nose (intranasally), a unique pathway to target deeper brain structures. While still considered an emerging field, PBM is also being investigated for a range of other neurological conditions, including traumatic brain injury, depression, and Alzheimer’s disease.

Cautious Optimism and the Path Forward

Experts not involved with the research have reacted with cautious optimism, noting that while the results are promising, the study's small size means larger, more definitive trials are essential. The lack of a clear winner for treating long COVID brain fog makes any positive signal from a rigorously designed trial significant.

The study’s authors are in full agreement, stressing that their work is a first step. They have outlined plans for future research, including larger trials to validate the findings across broader populations, exploring different treatment durations and dosing strategies, and integrating biomarkers like brain imaging and blood tests to understand who is most likely to benefit and why.

Long COVID remains a complex, multi-faceted illness, and it is unlikely that a single intervention will be a silver bullet for everyone. However, for the millions struggling to reclaim their mental clarity, this study offers a tangible sign of progress and a potential new avenue for recovery.

“Long COVID is a complex and heterogeneous condition,” Dr. Lim added. “No single intervention will work for everyone. People with long COVID brain fog are trying to get their lives back - back to work, back to thinking clearly, back to functioning. What this study shows is that a simple, home-based brain intervention can produce objective signals of improvement, and that is something worth paying attention to.”