Efficacy and safety of light therapy for Parkinson disease

To the Editor:Parkinson disease(PD)is the second most common neurodegenerative disorder associated with significant disability and negative impact on quality of life(QoL),affecting 2%to 3%of the population≥65 years of age.^([1])Although the disorder is defined by motor features including asymmetric tremor,bradykinesia,and rigidity,various non-motor features are typically seen,including cognitive impairment,depression,sensory symptoms,autonomic dysfunction,and sleep disturbances.Due to the complexity,PD is challenging to treat.There are currently no effective treatments to prevent or halt the progression of PD.