Effects of parkinsonian medication on sleep

Patients suffering from Parkinson's disease (PD) often report about sleep disorders and excessive daytime sleepiness. To some extent, motor disabilities or neural degeneration of sleep modulating structures may be responsible for these effects. Depressive disorders also contribute to the occurrence of insomnia and daytime sleepiness. Nevertheless, dopaminergic, anticholinergic, and other drugs used in PD have a great impact on sleep/wakefulness mechanisms. They may indirectly improve or worsen sleep by changing motor symptoms such as akinesia, hyperkinesia, or tremor. Although their is only little information on the complex regulation of vigilance, it is well known that monoaminergic and cholinergic drugs could influence it directly. Data from animal experiments and clinical experiences led to the hypothesis of a biphasic influence on sleep by dopaminergic substances: small doses of L-Dopa e. g. appear to improve sleep whilst higher doses led to insomnia. Different dopaminergic receptor types or changes in receptor sensitivity may explain these phenomena. Dopaminergic and anticholinergic drugs suppress REM sleep. Recently, initial data on 'sleep attacks' after pramipexole or ropinirole treatment were published. Our preliminary results using 24 h polygraphic recordings showed excessive daytime sleepiness in patients taking ropinirole and L-Dopa which disappeared when changed to ropinirole monotherapy. Sleepiness did never appear as an irresistible attack. Current hypotheses on this topic are reviewed.