Effect of bright light on mood and sleep in Parkinson's disease

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 primary aim of this study is to measure the effect of light therapy on mood
in depressed Parkinson patients. In addition, we measure the effect of light
therapy on sleep, motor functions, circadian rhythms and quality of life.

Double blind placebo controlled intervention study (RCT) with six months of
follow-up.

Treatment consists of twice daily exposure to bright light; 30 minutes in the
morning and evening for the time of three months. Halve of the patients are
exposed to high intensity light (10.000 Lux), the other halve to low intensity
light (200 Lux).

Light therapy is a very safe treatment and knows very little adverse effects.
The most important risk, retina damage, will be prevented by complying with
internationally handled exclusioncriteria, to make sure that patients with an
increased light sensitivity are excluded from participation. Light treatment
will be conducted at the patient's home for a period of three months, twice
daily for 30 minutes. During the exposure to the light treatment patients can
sit inside a chair and, for example, read a book. At six specific timepoints
during the study patients are invited to the neuropsychiatric Parkinson
outpatient clinic of of the VU Medical Center for a clinical interview, filling
in of questionnaires and saliva research. Furthermore, at six timepoints
patients are instructed to wear an actometer on the wrist for a period of one
week.