By Lucy Piper, Senior MedWire Reporter
Sleep patterns in patients with Parkinson's disease are affected by age, disease severity, and dopamine agonists, German research indicates.
The researchers from Paracelsus-Elena-Klinik in Kassel found that increased age leads to less sleep and a raised risk for rapid eye movement (REM) sleep behavior disorder (RBD); severe disease increases motor phenomena; and dopamine agonists reduce periodic leg movements in sleep (PLMS), but increase awakenings.
They note, however, that their findings displayed only a low explanation of variance, which implies that "factors not accounted for in this analysis play a major role in the destruction of physiological sleep in Parkinson's disease patients."
Among 351 sleep-disturbed but otherwise unselected Parkinson's disease patients whose sleep patterns were investigated using video-supported polysomnography, the average sleep efficiency was a total sleep time of 66% of time spent in bed, and the sleep latency was 18 minutes.
The patients, aged an average of 67 years, showed a mean 27 awakenings per night and were in REM sleep for just 16% of the total sleep time.
In addition, the amount of slow wave sleep was lower than normal, at 6% of total sleep time for men and 13% for women.
Average scores on PLM indices were increased, at 29 for all PLM, 29 for PLMS, and 24 for PLM during wakefulness. The rates of sleep-related breathing disorder and RBD were 37% and 51%, respectively.
As reported in Sleep Medicine, linear regression analysis showed that age was associated with a decrease in sleep efficiency and slow wave sleep, as well as an increase in the number of awakenings.
Higher disease severity, based on Hoehn & Yahr stages, for which the average among the patients was 3 out of a possible 5, was associated with more PLMS, suggesting an intensification of PLMS as the disease progresses, the researchers note. This sleep disturbance was lessened by dopamine agonists, but they in turn increased awakenings. Dopamine agonists also significantly decreased REM sleep.
Neither disease duration nor levodopa dosage influenced sleep efficiency, slow wave sleep, awakenings, or PLMS.
RBD occurrence was significantly associated with older age and a higher dose of levodopa, with the effects of disease duration and disease severity no longer significant after taking age into account.
Friederike Sixel-Döring and team found that the patients' perceived their sleep to be moderately to severely impaired, according to the Parkinson's disease sleep scale, but neither age, disease duration, disease severity, nor dopaminergic medication significantly influenced overall sleep quality or any single sleep item.
They conclude: "Apart from age, disease severity and dopamine agonists as disease-inherent interdependent factors impact the macrostructure of sleep in PD [Parkinson's disease] patients."
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