Can Light Therapy Help the Brain Recover from Injury and Stroke?
Possibly. This review found that photobiomodulation with near-infrared light improved brain function and reduced inflammation in animal models of traumatic brain injury, and animal work suggests it may even stimulate the growth of new brain cells. Small clinical studies in people with chronic brain injury have reported improvements in executive function, working memory, and sleep.
Red light therapy, also known as low-level laser therapy (LLLT) or photobiomodulation (PBM), uses specific wavelengths of red and near-infrared light to promote healing and reduce inflammation.
Traumatic brain injury (TBI) is approaching global epidemic levels, and stroke remains one of the leading causes of disability worldwide. For both conditions, there is a critical shortage of treatments that actively promote brain recovery. Photobiomodulation (PBM) uses red or near-infrared light (600-1100 nm) to stimulate healing, protect tissue, and improve blood flow. This review examines the full range of evidence for PBM in brain injury and stroke recovery.
What the Research Shows
The review covers several categories of evidence. In animal models of acute TBI, PBM consistently improved neurological function, learning, memory, and reduced inflammation and cell death in the brain. In healthy human volunteers, including university students and elderly women, PBM increased regional cerebral blood flow and tissue oxygenation, and improved memory, mood, and cognitive function. In clinical studies of patients with chronic TBI effects, PBM improved executive function, working memory, and sleep. Functional MRI imaging showed that PBM changed activation patterns in brain networks known to be damaged by TBI, specifically the default mode network and salience network. In animal studies, there is also evidence that PBM can stimulate neurogenesis (growth of new brain cells), increase BDNF synthesis (a protein crucial for brain cell survival and growth), and encourage synaptogenesis (formation of new connections between brain cells). For acute stroke, the human results are mixed: earlier trials were encouraging, but the largest trial, NEST-3, was stopped early because it was unlikely to show a benefit.
Dr. Kumar’s Take
The animal evidence that PBM can stimulate neurogenesis and BDNF production matters. The adult brain can grow new cells under the right conditions, and PBM may be one of those conditions. The improvements in executive function and working memory reported in chronic TBI patients also matter, because these are the cognitive abilities that allow people to plan, organize, and function independently. Functional MRI showing changes in brain network activation after PBM points to a measurable effect, though the human studies so far are small.
Beyond Symptom Relief
What sets PBM apart from most TBI and stroke treatments is that animal studies suggest it may promote actual brain repair, not just symptom management. By stimulating neurogenesis and synaptogenesis, PBM may help rebuild some of the neural architecture damaged by injury. By increasing BDNF, it supports the survival and growth of existing neurons. And by improving cerebral blood flow and tissue oxygenation, it creates a better environment for the brain to heal itself.
Practical Takeaways
- Red light therapy has shown improvements in executive function, working memory, and sleep in patients with chronic TBI effects.
- In healthy volunteers, PBM improved memory, mood, and cognitive function while increasing cerebral blood flow.
- In animal studies, PBM stimulated neurogenesis and BDNF production, which may support brain repair rather than just symptom relief.
- Near-infrared light delivered via lasers or LEDs can reach brain tissue through the skull, though only a small fraction of it gets through.
FAQs
How long after a brain injury or stroke can PBM still help?
The review includes studies of patients with chronic TBI effects, meaning months to years after the initial injury. The evidence suggests that PBM can still provide meaningful improvements even in chronic cases. The brain retains some capacity for repair and reorganization throughout life.
Can PBM help with the emotional and psychological effects of brain injury?
Possibly. The review reports improved mood in healthy volunteers, not specifically in brain injury patients. Since PBM also shows promise for depression and anxiety as standalone conditions, it may help with some of the emotional symptoms that commonly accompany brain injury and stroke recovery.
What type of PBM device is best for brain recovery?
The best device and dose are not settled. The review notes some consensus that near-infrared wavelengths around 800 to 900 nm penetrate the scalp and skull, while other groups have used longer wavelengths. Transcranial and intranasal LED devices can be used at home for long-term treatment.
Bottom Line
Red light therapy may offer both neuroprotective and neuroregenerative effects for brain injury and stroke recovery. Early evidence shows improvements in cognitive function, blood flow, and brain network activation, with the potential to stimulate actual brain repair through neurogenesis and synaptogenesis. For anyone dealing with the effects of brain injury or stroke, PBM is a promising but still experimental option worth discussing with a doctor.
