Sleep disturbances in Parkinson's disease

Sleep disturbance is one of the major sources of dissatisfaction with the quality of life among patients with Parkinson's disease (PD). Nowadays it is clear that parkinsonian symptoms, tremor and rigidity, are alleviated during sleep. The prevalence of sleep disturbances is difficult to ascertain; reports vary from 98% to 74% to 81% to 73%, including patients suffering from excessive daytime sleepiness. Gender does not seem to play a clear role, although females may be more affected. Difficult sleep maintenance (light and fragmented sleep) and difficulties with sleep initiation are the earliest and most frequent sleep disorders observed in PD. Other common sleep-associated complaints include parasomnias and excessive daytime sleepiness (EDS)-that is, inappropriate and undesirable sleepiness during waking hours. Surveys of the general population have shown that between 0.5% and 5% complained of EDS; even in a large study in an elderly population, about 20% of the subjects reported 'usually sleepy in the daytime'. EDS is more common in PD. PD itself is one of the causes of sleep disturbance. Alteration of sleep-wake regulation may result from the disease process involving neuronal loss of locus coeruleus, substantia nigra, retrorubral nucleus, and pedunculopontine nucleus. The severity of parkinsonian symptoms influences the degree of sleep disturbance. Other common sleep-related motor complaints, including nocturnal akinesia, dystonia, and painful cramps, are observed in parkinsonian patients who developed motor fluctuations (on-off phenomenon, wearing off) during the day Depression is another common cause of sleep disturbance. Other common disturbances are nocturia, fragmentary nocturnal myoclonus, periodic leg movements of sleep, restless legs syndrome (RLS), and nocturnal akathisia. In this paper, the preliminary results of our survey on sleep disturbances in PD patients are also reported.