Sleep disturbances are common in Parkinson's disease and include excessive daytime sleepiness that has been reported in up to 50% of patients. Relatively little therapeutic research has addressed the problem of excessive daytime sleepiness and current treatment is largely aimed at reducing the dose of dopaminergic medication while trying to maintain sufficient motor control which unfortunately often fails. Apart from degeneration of dopaminergic neurons, a decrease in cholinergic projections to the brain arousal areas may be at least partly responsible for the occurrence of excessive daytime sleepiness in Parkinson's disease. Smoking in narcoleptic patients diminishes sleep attacks and excessive daytime sleepiness , thus one may hypothesize that nicotinergic stimulation of the brain arousal areas may improve excessive daytime sleepiness in Parkinson's disease. Therefore the effect of varenicline, an alpha4beta2 nicotinic receptor partial agonist, on excessive daytime sleepiness in Parkinson's disease will be studied in a placebo-controlled cross-over study.
The effect of varenicline, an alpha4beta2 nicotinic receptor partial agonist on excessive daytime sleepiness in Parkinson's disease will be studied in a randomized, double blind, placebo-controlled clinical trial with a within-subject crossover design.