RBD tied to broader motor, psychiatric problems in Parkinson’s disease

People with Parkinson’s disease with REM sleep behavior disorder (RBD) showed a broader pattern of motor, psychiatric, and daily-function problems than those with insomnia or sleep apnea, according to a large database study.

RBD was particularly strongly associated with slowed movement, or bradykinesia, and hallucinations, as well as difficulties with several everyday activities. Having multiple sleep disorders was also associated with progressively greater clinical impairment. Additionally, the results suggested that motor impairment may partly help explain the association between sleep problems and difficulty performing daily activities, although the researchers stressed that the study cannot establish cause and effect.

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Oct. 2, 2026 News by Patricia Inácio, PhD

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Sleep disorders show different patterns of problems in Parkinson’s

“Overall, distinct sleep disorders in [Parkinson’s disease] were associated with different functional profiles,” researchers wrote, adding that the findings require confirmation in studies that follow patients over time before they can be translated into clinical practice.

The study, “Beyond motor symptoms: associations between sleep disorders and multidomain functional decline in Parkinson’s disease,” was published in the journal npj Parkinson’s Disease.

Parkinson’s is a progressive neurological disease best known for motor symptoms such as tremor, muscle stiffness, and bradykinesia. But the disease also causes a range of nonmotor symptoms that can substantially affect quality of life and independence.

Sleep problems are particularly common, affecting as many as 90% of people with Parkinson’s at some point during the disease. Common examples include RBD, insomnia, and sleep apnea.

RBD occurs when the normal temporary paralysis of muscles during REM sleep is lost, causing people to physically act out their dreams. Insomnia involves problems falling or staying asleep, while sleep apnea involves repeated pauses or reductions in breathing during sleep.

Sleep disturbances have been linked to motor problems, cognitive difficulties, and psychiatric symptoms in Parkinson’s. They may also affect instrumental activities of daily living — more complex everyday tasks needed for independent living, such as preparing meals, shopping, managing finances, and using transportation.

According to the researchers, however, most prior research has examined a single type of sleep disorder or a single area of functioning at a time.

Study compares problems linked to 3 common sleep disorders

Here, the team sought to determine whether RBD, insomnia, and sleep apnea were associated with distinct patterns of motor, cognitive, psychiatric, and daily-function problems, and to explore how sleep problems might be connected to loss of independence in Parkinson’s.

They analyzed data from 9,195 adults in the U.S.-based National Alzheimer’s Coordinating Center database, including 884 people with Parkinson’s and 8,311 controls. After statistical weighting, the Parkinson’s group had a median age of 77 and was 58.9% male; the control group had a median age of 76 and was 57.8% male.

In the weighted analysis, RBD was recorded in 36.6% of those with Parkinson’s compared with 16.6% of controls. Insomnia was present in 18.7% of people with Parkinson’s (vs. 17.2% in controls), and sleep apnea in 23.2% (vs. 25% in controls).

After accounting for measured demographic and cognitive factors, the three sleep disorders showed markedly different clinical patterns. People with RBD had about fivefold higher odds of bradykinesia and hallucinations. RBD was also linked to difficulties with several activities required for independent living, including paying bills, preparing meals, shopping, and managing tax records.

Insomnia showed a more mixed pattern. It was associated with depression but was not consistently associated with greater difficulty performing everyday activities. Sleep apnea showed a more limited set of associations than RBD.

The researchers also examined whether having several sleep disorders at the same time was associated with greater clinical difficulties.

Among people with Parkinson’s who had none of the three sleep disorders, 49.9% had bradykinesia. That rose to 80% among those with all three sleep disorders. Compared with having no sleep disorder, the odds of bradykinesia increased progressively with one, two, and three sleep disorders, reaching about fourfold higher odds among those with all three.

A similar pattern emerged for hallucinations, which occurred in 11.4% of those without a sleep disorder and 35.4% of those with all three. Overall, the findings suggested that a greater burden of overlapping sleep problems was associated with broader clinical impairment.

Motor problems may partly explain sleep, daily-function link

An exploratory analysis also suggested that motor impairment may help explain part of the link between sleep problems and difficulty performing daily activities. In the statistical model, motor impairment accounted for 35.8% of that association. Because sleep disorders, motor symptoms, and daily functioning were measured at the same time, however, the analysis could not determine whether sleep problems led to greater motor impairment or later loss of independence.

Researchers also used machine-learning models to see how well combinations of clinical features could identify people with each sleep disorder. The models were better at identifying RBD than insomnia or sleep apnea, with an area under the curve (AUC) of 0.851 for RBD, compared with 0.667 for insomnia and 0.666 for sleep apnea. AUC is a statistical measure of how well a model distinguishes between people with and without a particular condition. A value of 0.5 indicates performance no better than chance, while 1 indicates perfect discrimination.

However, these results were exploratory and were tested only within the same database, meaning the models need to be tested in other groups of people before they can be used in clinical practice.

Overall, the findings suggest that different sleep disorders are linked to different patterns of problems in Parkinson’s. RBD showed the broadest range of associations, while having more overlapping sleep disorders was associated with greater overall impairment.

According to the team, long-term studies and clinical trials will be needed to determine whether treating sleep problems can improve motor symptoms, independence, or other aspects of Parkinson’s disease.