Exploring light therapy for Parkinson’s

Light is a form of energy with many jobs, from helping plants to grow, to allowing us to see. There’s a huge spectrum of light, from light that we can see, called visible light, to some that we can’t, such as infrared and ultraviolet light.

What is light therapy?

Exploring whether light can be used in medicine is not a new idea, but it is becoming a more active area of research. There are many different types and ways of using light therapy. But generally, light therapy involves using light to create a response in the body to treat or improve a symptom or condition.

What light therapy is being explored for Parkinson’s?

For Parkinson’s, different types of light therapy are being investigated. They include bright light therapy and infrared light therapy.

Bright light therapy

Bright light therapy is an approved treatment for Seasonal Affective Disorder (SAD). SAD is a type of depression that people can experience in the winter months, when there is limited exposure to the sun. Bright light therapy involves exposing an individual to a bright light which mimics sunlight. It’s thought that the bright light affects hormone production in the brain, and can improve wellbeing and day time sleepiness.

In Parkinson’s, many people experience non-movement symptoms which include sleep difficulties and low mood. Researchers are exploring bright light therapy as a possible solution:

• A 2024 study investigated the effect of natural daylight on quality of sleep in people with Parkinson’s. They also looked at the effect of the light on people’s internal body clocks, as this can impact sleep. 60 participants took part, and were exposed to either daylight, or an enhanced version of daylight. 
  The results showed that both therapies improved deep sleep in people with Parkinson’s. These early results suggest that exposure to daylight in a controlled manner could be effective for improving sleep in Parkinson’s.

Read the published paper in The Lancet.

• A much smaller study, involving 23 people, also explored whether bright light therapy could improve symptoms of Parkinson’s, compared to dim light in a crossover trial. The researchers also wanted to understand how light might be helping, specifically looking at how the eyes and the brain communicate. The results showed that bright light therapy improved excessive daytime sleepiness, anxiety and overall quality of life for people with Parkinson’s.

Read the published paper in Biomed Central Psychiatry.

Bright light therapy has also been explored for depression in Parkinson’s. As many as 3 in 10 people with Parkinson’s will experience depression, and specialist care is a huge unmet need.

• One study carried out in 2019 involved 83 people with Parkinson’s. Participants were treated with either bright light or a control light for 3 months. They found that bright light therapy wasn’t more effective in reducing symptoms of depression than the control light, but that mood and sleep improved in both groups.

Read the published paper in Neurology.

More research is needed to better understand the potential of bright light therapy to treat non-movement symptoms of Parkinson’s. At the moment, it is not an approved treatment for the condition.

Infrared light therapy

Another type of light therapy being explored is called photobiomodulation (PBM), or infrared light therapy. This treatment uses infrared or near-infrared light, which is light with a much longer wavelength than the light that we can see.

Our bodies can absorb different wavelengths of light. Longer wavelengths, like those of infrared light, are thought to be better absorbed by specific parts of our cells. This includes structures that produce energy inside cells, called mitochondria. So some researchers think that infrared light could help our cells produce more energy, which may protect and restore cells in our body.

This is particularly interesting for conditions like Parkinson’s, where brain cells become damaged over time. Infrared light therapy is being explored to see whether it can offer protection to these struggling brain cells. Research is still in the early stages, but studies have shown that infrared light therapy may have the potential to improve symptoms of the condition.

Ongoing research

In August 2025, results were published from the largest study to date that has explored the effectiveness of infrared light therapy combined with exercise to improve symptoms of Parkinson’s. The trial took place in 3 stages and used light therapy devices manufactured by SYMBYX Biome, a registered company based in Australia.

In stage 1, 63 people were randomly assigned either infrared light therapy or placebo light therapy 3 times a week for 8 weeks. In stage 2, all participants received infrared light therapy for 8 weeks, and in stage 3, participants could choose to either continue treatment or receive no treatment for up to 48 weeks. During all stages, participants also took part in vigorous exercise.

The results showed that there was no significant difference between participants after stages 1 and 2. However, after stage 3, those who had continued with the treatment had improved mobility and balance, as well as reduced anxiety, compared to participants who had stopped the treatment.

These early findings indicate that infrared light therapy, combined with an exercise programme, may help manage symptoms of Parkinson’s. However, this study makes it hard to know the benefit that the light itself might have had. And we already know that exercise by itself can be beneficial for people with Parkinson's. We need further research to explore how light therapy might be adding to this.

Read the full published paper in The Journal of Clinical Medicine.

In 2026, 2 more studies will start in collaboration with SYMBYX Biome: 

• At the University of Leeds, researchers aim to investigate how infrared light therapy may affect the gut and will look specifically at human gut cells in the lab. In Parkinson’s, many people experience problems with their gut. This study may help us understand how infrared light therapy could help manage these problems.
• At the University of Newcastle, a clinical trial involving 80 people with Parkinson’s will test the effectiveness of infrared light therapy on Parkinson’s symptoms. The study is not yet recruiting participants. Join the Research Support Network to stay up to date as the trial starts.

Can I use a light therapy device?

Although light therapy is thought to be safe, it’s not an approved treatment for Parkinson’s. More research, including larger and controlled clinical trials, is needed to understand the benefits to people with Parkinson’s, as well as to help understand the long term impact of this type of therapy.

However, light therapy devices are on the market. Many are marketed to people with Parkinson’s and often come with a hefty price tag. Without research evidence, it’s not possible to know whether these devices will be helpful.Our Tech Guide features reviews from community members about how they’re finding light therapy devices, to help you make an informed decision about whether they might be for you. You can read these on the Tech Guide pages.

If you need support or have any questions, please get in touch with the Research team at [email protected].