Excessive daytime sleepiness and unintended sleep in Parkinson's disease

Patients with Parkinson's disease and parkinsonian syndromes (eg, dementia with Lewy body disease, multisystem atrophy, and Shy-Drager syndrome) suffer from daytime sleepiness. This sleepiness is common and very real, often approaching levels observed in the prototypical disorder of sudden-onset sleep, namely narcolepsy/cataplexy. Physicians need to be vigilant in assessing parkinsonian patients for sleepiness because treatment can dramatically enhance quality of life and prevent the significant morbidity and mortality that attends daytime sleepiness. Male patients with advanced disease, cognitive impairment, drug-induced psychosis, and orthostatic hypotension are most at risk for developing pathologic sleepiness. Because primary sleep disorders can coexist with parkinsonism (eg, sleep apnea, insufficient or interrupted sleep), these potential causes should be carefully assessed with polysomnography and treated appropriately. Dopaminomimetics exacerbate sleepiness in a small subset of patients in a dose-dependent fashion. Nonetheless, the primary pathologies involved in parkinsonism appear to be the greatest contributors to daytime sleepiness. Sleepiness in parkinsonism, especially a narcolepsy-like phenotype, may necessitate treatment with wake-promoting agents such as bupropion, modafinil, or traditional psychostimulants.