The quality of life of patients with Parkinson's disease and their caretakers is mainly influenced by so called non-motor symptoms. This includes neuropsychiatric consequences of the disease like depression and sleeping problems. The incidence of depressed mood in patients with Parkinson is approximately 50%, the incidence for sleeping problems is 90%. These symptoms are often overlooked and even if recognized, inadequately treated. The treatment of mood and sleep disturbances in Parkinson patients is hampered by adverse effects, incomplete responses to the usual treatments and the absence of specific treatment options for these symptoms in Parkinson's disease. On the basis of the hypothesis of disturbed functioning of the suprachiasmatic nucleus in Parkinson's disease it is expected that stimulation of this nucleus by bright light therapy will result in improved functioning on multiple different domains: mood, sleep, motor functions, quality of life and circadian rhythms. Because there are virtually no side effects and the possibility of home treatment, light therapy is expected to be highly appreciated by the patients.
The purpose of this clinical trial is to investigate whether light therapy is a suitable treatment option for depression and insomnia in Parkinson's disease.