Sleep-wake disturbances in Parkinson's disease: current evidence regarding diagnostic and therapeutic decisions

Sleep disorders have been frequently reported in patients with Parkinson's disease (PD). However, there is insufficient evidence to guide precise recommendations on some diagnostic and treatment strategies. Here, we review clinical studies dealing with sleep abnormalities in PD and present clinical recommendations. Previous studies describing insomnia, excessive daytime sleepiness, narcolepsy-like episodes, circadian changes, sleep-disordered breathing, rapid eye movement sleep behavior disorder, vivid dreams and restless legs syndrome are evaluated. Longitudinal studies associating sleep disorders with PD onset or clinical deterioration are rare: only one longitudinal study associated daytime sleepiness with PD onset. Evidence suggests that clinical investigations must include direct questioning about depressive symptoms, nocturnal cramps, pain, nocturia and nighttime off periods. A patient interview must be conducted regarding sleep symptoms, including nightmares, abnormal behavior during sleep, snoring, restless legs syndrome and daytime sleepiness. Initial evidence indicates that light therapy improves motor function and depression. Advice on sleep hygiene, the treatment of concomitant depression and the careful use of dopaminergic drugs and hypnosedative agents should be considered. To date, very few controlled studies are available to make a recommendation for the management of sleep-wake disturbances in PD.