Learn about the effectiveness of Light Therapy for treating Parkinson’s
In clinical trials for Parkinson’s disease (PD), light therapy, or the use of light as a treatment for PD symptoms, shows the most promise for sleep disorders, but has varied success for other motor and non-motor symptoms of PD.
Light therapy encompasses a broad category of treatments involving different types of light and delivery systems. Past research and ongoing clinical trials are helping to clarify how and where this approach may fit into PD care.
To better understand what we currently know and what remains uncertain, this overview explores:
- Why might light therapy be helpful in PD?
- What are the variables to consider when thinking about light therapy?
- Which symptoms of PD may experience relief with light therapy?
- Are there any currently available devices for light therapy to treat PD symptoms?
- What clinical trial data supports the use of light therapy in PD?
- What newer and ongoing clinical trials are shaping the field?
- What do we still not know about light therapy for PD?
Why might light therapy work in PD?
Several biological mechanisms continue to be investigated for why light therapy might deliver positive effects on PD symptoms.
Three leading theories include:
- Circadian rhythm regulation: Light influences the body’s internal clock through the suprachiasmatic nucleus. Since circadian disruption is common in PD, light therapy may help restore normal rhythms, including sleep. Blue light appears especially effective in this role.
- Dopamine system modulation: Light exposure may influence dopamine signaling which can potentially improve motor symptoms.
- Mitochondrial function and cellular energy: Near-infrared light is absorbed by components of the mitochondria, which may enhance energy production and reduce cellular stress. Since mitochondrial dysfunction plays a role in PD, this is an important area of interest.
The many variables of light therapy for Parkinson’s
There is a long list of variables to consider when thinking about how light can be delivered as a treatment, and each variable can affect its therapeutic potential.
What part of the light spectrum is being used?
Three main wavelengths continue to be studied:
- Full spectrum light, also called white light
- Near-infrared light (NIR), typically in the range of 700 to 1300 nanometers
- Blue light (around 460 to 480 nanometers), which is thought to most strongly influence circadian rhythm (the body’s own biological clock)
How is the light being delivered?
Delivery methods vary depending on the wavelength:
- White light is typically delivered through the eyes using light boxes or screens
- Near-infrared light is not visible and is delivered more directly using specialized systems
Additional delivery approaches include:
- Wearable helmets designed to allow light to penetrate the scalp and skull
- Intranasal delivery systems
- Implanted light-emitting devices targeting deeper brain structures
Newer studies are increasingly focusing on non-invasive and at-home delivery systems, which reflect how the therapy would realistically be used if proven effective.
What is the brightness of the light?
Many clinical trials continue to use brightness levels in the range of 10,000 Lux for white light therapy.
For context:
- Moonless night: ~0.0001 Lux
- Overcast day: ~100 Lux
- Daylight: ~10,000 Lux
What is the length and frequency of treatment?
Past and current trials typically use:
- 30 to 60 minutes per session
- Once or twice daily exposure
- Treatment durations ranging from weeks to many months
More recent trials are also examining long term, daily use over a year or more, which is especially important for a chronic condition like PD.
Which symptoms of PD may respond to light therapy?
A range of PD symptoms have been studied in relation to light therapy.
Symptoms most commonly investigated include:
- Sleep disorders and circadian rhythm disruption
- Depression and anxiety
- Fatigue
- Motor symptoms such as movement and coordination
Recent studies continue to support sleep improvement as the most consistent benefit, particularly with bright light therapy. There is also increasing evidence that motor and non-motor symptoms may improve, but the results are varied across different studies.
Available light therapy devices
Because light therapy delivered via the eyes or skin is generally low risk, many devices are already commercially available.
These include:
- White light boxes
- Wearable light delivery systems
- Red and near-infrared (NIR) light devices
Of note, red light therapy which is visible to the human eye (wavelengths 620-750 nm) is a very popular wavelength for use in health-related devices, particularly skin conditions. While there have been some studies regarding red light and Parkinson’s disease, red light (620–750 nm) penetrates tissue less deeply than NIR (700-1300 nm). NIR light can penetrate the skull and reach deeper brain structures more effectively, which is why it is used more frequently in clinical trials for neurological conditions.
It is important to note that these devices are often marketed for other conditions such as sleep disorders, depression, or skin health, and there are still no widely approved devices specifically indicated for PD. Despite this, newer investigational devices designed specifically for PD are now being tested in advanced clinical trials.
Past clinical trial data on light therapy for Parkinson’s
Earlier clinical trials laid the foundation for current research.
- Most studies were small and used varying parameters
- White light trials used intensities between 1,000 and 10,000 Lux
- Exposure times ranged from 30 minutes to 1.5 hours
- Timing varied between morning, evening, or twice daily
Across these studies:
- Many showed improvements in sleep, mood, and some motor symptoms
- Results were promising but inconsistent
- Differences in study design made comparisons difficult
Near-infrared light studies also showed early signals of benefit in mobility, cognition, and balance, despite the small sample sizes.
Updated clinical trial landscape
Newer studies have built on the findings of older studies and include larger population sizes and longer trial durations, making potential results more actionable.
Recent studies have moved beyond short pilot trials:
- A 72-week randomized controlled trial reported improvements in mobility, balance, and quality of life, especially when light therapy was combined with exercise
- The Celeste phototherapy device is being studied in a Phase 3 clinical trial
- A randomized, double-blind Phase 2 daylight exposure trial in 2024 compared natural and enhanced daylight exposure for 60 individuals and both groups showed improvement in deep sleep quality compared to the control group suggesting that even natural light modulation may have therapeutic benefits
- A long-term (five year) clinical follow-up on photobiomodulation in PD published in 2026 continues to analyze an ongoing multi-site photobiomodulation therapy on a small cohort to show sustained improvement in mobility, balance, cognition, and smell maintained over five years with continued treatment with no serious safety concerns. Larger studies are still needed to confirm these findings.
Expansion of at home treatment models
Many current trials are designed around real-world application by incorporating daily use for 30 to 60 minutes, at-home treatment settings, and long-term adherence and safety monitoring. This reflects a shift toward making light therapy a practical and scalable intervention if proven effective.
What we still do not know about light therapy treatment for Parkinson’s
Despite progress, key questions remain:
- Which type of light therapy works best for specific symptoms
- Optimal treatment parameters such as intensity, timing, and duration
- Which patients are most likely to benefit
- Long-term effectiveness across large populations
The evidence continues to build that light therapy may play a role in managing symptoms of PD. Some of the strongest leads continue to support its use for sleep disturbances, while newer research suggests possible benefits for motor and other non-motor symptoms. It is important to manage expectations as light therapy remains an investigational approach, and additional large-scale clinical trials are needed to define its role in standard care.
Tips & Takeaways
- A variety of PD symptoms may respond to light therapy, including sleep, mood, fatigue, and motor function
- Bright light therapy has the most consistent evidence, particularly for sleep improvement
- Near-infrared therapies look promising but are still under investigation
- Clinical trials have expanded significantly, including long-term and Phase 3 studies
- At-home treatment models are becoming a major focus of research
- Light therapy may work through circadian regulation, dopamine signaling, and mitochondrial support
- More research is needed to determine optimal treatment protocols and long-term effectiveness
This blog was written by Clark Jones, PhD, and was reviewed, edited, and approved by Dr. Rebecca Gilbert.