Sleep disturbances are common in Parkinson's disease and can appear prior to the onset of motor symptoms, scientists say.
Up to 70 per cent of Parkinson's disease (PD) patients experience sleep problems that negatively impact their quality of life, researchers said.
Some patients have disturbed sleep/wake patterns such as difficulty falling asleep or staying asleep, while other patients may be subject to sudden and involuntary daytime sleep "attacks."
In the extreme, PD patients may exhibit REM-sleep behaviour disorder (RBD), characterised by vivid, violent dreams or dream re-enactment, even before motor symptoms appear.
A review in the Journal of Parkinson's Disease discusses the underlying causes of sleep problems in PD, as well as medications, disease pathology, and comorbidities, and describes the most appropriate diagnostic tools and treatment options.
Lead author Wiebke Schrempf, Technische Universitat Dresden, Faculty of Medicine Carl Gustav Carus, Department of Neurology, Division of Neurodegenerative Diseases, Dresden, Germany and colleagues describe some of the complexities associated with treating sleep problems in PD patients, such as the worsening of sleep problems by dopaminergic medications used to treat motor symptoms.
Lower doses of levodopa or dopamine agonists are able to improve sleep quality partly by reducing motor symptoms such as nighttime hypokinesia (decreased body movement), dyskinesia (abnormal voluntary movements), or tremor (involuntary shaking), which interfere with normal sleep.
However, the same medications may also cause excessive daytime sleepiness. The report describes how changing medication, dose, duration of treatment, or timing of administration can improve outcomes.
Sleep problems may also be harbingers of future neurodegenerative disease, researchers said.
Patients with RBD exhibit intermittent loss of normal muscle relaxation during REM sleep and engage in dream enactment behaviour during which they may shout, laugh, or exhibit movements like kicking and boxing.
"RBD seems to be a good clinical predictor of emerging neurodegenerative diseases with a high specificity and low sensitivity, whereas other early clinical features of PD, such as olfactory dysfunction and constipation, are less specific," said Schrempf.
"These early clues may help identify PD patients before motor symptoms appear, when disease-modifying therapies may be most beneficial," Schrempf said.