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Photoreceptor-directed Light Therapy in Parkinson’s Disease

Study Rationale: Non-motor symptoms including sleep disturbances are common and enormously impact on the quality of life in people with Parkinson’s disease. Sleep disruption affects motor function and can occur before motor symptoms. Bright Light Therapy can successfully reduce these symptoms, however new therapeutic lighting approaches are required to fully harness the beneficial effects of light. We recently demonstrated that melanopsin cells in the eye that provide the main light signal to the brain for initiating sleep, are impaired in PD. Selectively illuminating these cells is the next advance in understanding the effects of light in PD and for developing therapeutic recommendations.

Hypothesis: We will determine the underlying pathways from the eyes that lead to sleep disruption in people with PD using our newly developed lighting technology that selectively illuminates melanopsin cells to improve non-motor and motor behaviours in PD.

Study Design: In the morning or evening during 4-weeks, people with Parkinson’s disease will view a light that increases or decreases their melanopsin activity in the eye. Because both lights have the same (white) appearance, we can use a study design where both, the investigators and participants are unaware of their light treatment condition. We determine melanopsin cell function using non-invasive methods (pupillometry) established in our laboratory and monitor sleep and motor behaviors before and after light intervention. Together the measured battery of sleep and motor function parameters and their change after light treatment will facilitate new recommendations for light therapy.

Impact on Diagnosis/Treatment of Parkinson’s Disease: The study results will impact on the non-invasive treatment of sleep disturbances. Our lighting technology might reduce the non-motor and motor symptoms and positively affect conventional drug treatment regimens and lead to reduced dosage and/or use, as well as reduce the wear-off effects of drugs.

Next Steps for Development: The results will inform phase III clinical trials that assess optimum conditions for light therapy to maximize efficacy. We will transfer the knowledge to industry partners to produce PD specific lights. The outcomes will empower participants to take control of their symptoms by using personalized lighting within their homes.

Trial Phase: Phase II (proof of concept)


  • Beatrix Feigl, MD, PhD

    Brisbane QLD Australia

  • Andrew James Zele, PhD

    Brisbane QLD Australia

  • Graham Kerr, PhD

    Brisbane QLD Australia

  • Simon Lewis, MD

    New South Wales Australia

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