A new study confirms the idea of a "sleep benefit" for people with Parkinson's disease -- meaning that their motor functioning seems to be better in the morning after they've just woken up.
"If the subjective experience of sleep benefit is proven to be related to an objective improvement in motor function, this could have considerable clinical benefits," study researcher Dr. Sebastiaan Overeem, M.D., Ph.D., of the Donders Institute for Brain, Cognition, and Behavior at Radboud University Nijmegen Medical Centre, said in a statement.
Parkinson's disease is characterized by tremors, muscle stiffness and movement problems, according to the Mayo Clinic.
The Journal of Parkinson's Disease study included 243 people with Parkinson's. Researchers found that 46.9 percent of them seemed to experience this benefit, even though there didn't seem to be a difference in the quality of rest experienced by people who experienced the sleep benefit and those who didn't.
In addition, researchers reported in the study that about a third of the study participants experienced a sleep benefit even after taking a nap.
"Sleep benefit remains an intriguing but elusive phenomenon, which deserves renewed attention and further research," they wrote in the study.
Researchers came up with several possible reasons for the finding, though they noted that they don't know the exact mechanism. Some possible reasons include improved functioning of dopamine (people with Parkinson's are known to have low concentrations of dopamine, according to the Mayo Clinic), or effects on the circadian rhythm.