The significant impact of Parkinson disease on sleep was clearly noted in James Parkinson’s remarkable description of the illness in his 1817 monograph, “An Essay on the Shaking Palsy.” He correctly noted that the motoric symptoms of Parkinson disease, such as severe nocturnal emergent tremor or nocturnal immobility, have great potential to interrupt sleep. Today, we are aware that the sleep-Parkinson disease interaction takes many other forms, including the effect of Parkinson drugs or Parkinson-associated behavioral symptoms (depression and psychosis) on sleep, and the (mostly beneficial) effect of sleep on the symptoms of the disease. The authors highlight the common sleep disorders found in Parkinson disease, looking at both the potential etiologies and treatment options. One of the most striking sleep problems in Parkinson disease is excessive daytime sleepiness, which is in part due to medication side effects, but also highly correlated with age and duration of disease. We have also learned that many sleep disorders that are moderately common in the general population, such as restless legs syndrome and REM sleep behavior disorder, could be more prevalent among Parkinson patients, the latter condition sometimes antedating clinical Parkinson disease by years. Finally, this update discusses the role of circadian disruption in the development of Parkinson disease, an exciting new area of research and potential intervention.
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• REM sleep behavior disorder is 1 of the most common sleep disorders associated with Parkinson disease and sometimes antedates the motoric features of Parkinson disease by years.
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• Daytime sleepiness and fatigue are common complaints in Parkinson disease patients, especially in the elderly and in men.
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• Circadian dysfunction is an important emerging component of sleep dysfunction in Parkinson disease, with recent demonstration of changes in melatonin release patterns and potential benefits seen from timed bright light exposure.
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• The common notion that parkinsonian tremor disappears entirely during sleep is not completely true as tremor can re-emerge, sometimes significantly, during sleep arousals.
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• Bedtime dosages of dopaminergic medications, especially long-acting preparations, are very useful to combat nocturnal re-emergent parkinsonian symptoms, such as high-amplitude tremor or severe akinesia, while in bed, which can significantly disrupt sleep.
Historical note and terminology
In 1817 James Parkinson, a medical practitioner from the township of Shoreditch, published his remarkable monograph entitled “An Essay on the Shaking Palsy.” In this monograph he described 6 patients he had observed with a unique neurologic disorder that would later come to bear his name. In the first 6 lines of this monograph, he confirmed the prominent clinical features of this condition much as we know them today:
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. . . involuntary tremulous motion, with lessened muscular power, in parts not in action and even when supported. . . with a propensity to bend the trunk forwards, and to pass from a walking to a running pace. . . the senses and intellects being uninjured.
In addition to its classical features, Parkinson was also well aware of the syndrome’s interaction with sleep. On page 7 of his 63-page monograph he noted, “The tremulous motion of the limbs occurs during sleep, and augment until they awaken the patient and frequently with much agitation and alarm.” Commenting on the potential severity of tremor in advanced Parkinson patients, Parkinson goes on to state, “but even when exhausted nature seizes a small portion of sleep, the motion becomes so violent as not only to shake the bed-hangings, but even the floor and sashes of the room” (74). Parkinson’s vivid and concise descriptions of this syndrome and its accompaniments remain among the most remarkable and venerated accomplishments in clinical neurology. Although he coined the Latinized term “paralysis agitans” in place of shaking palsy, both terms have gradually disappeared in favor of Parkinson disease, the title that honors the master clinician. Today, even those conditions that clinically resemble Parkinson disease, although they are histologically different, are referred to collectively as the Parkinson syndromes.