Light Therapy Treatment in Parkinson's Disease Patients With Daytime Somnolence

Study objectives are to determine the efficacy, safety and tolerability of bright light treatment in Parkinson's Disease (PD) patients with daytime sleepiness. Thirty PD patients will be enrolled and equally randomized to bright light or dim-red light treatment. Objective (actigraphy) and subjective (sleep logs/scales) sleep measures will be collected through the baseline and intervention phases of the study. The primary outcome measure will be the change in the Epworth Sleepiness Scale (ESS) comparing the bright light treatment with dim-red light treatment. Secondary outcome measures will include the Multiple Sleep Latency Test (MSLT), global Pittsburgh Sleep Quality Index (PSQI) score, Parkinson's Disease Sleep Scale (PDSS) score, and actigraphy measures. A variety of exploratory analyses will examine the effects of bright light treatment on fatigue, depression, quality of life, cognition, and motor disability. Hypothesis: Bright light exposure will diminish daytime sleepiness and improve night-time sleep in PD patients with daytime sleepiness.