This study examines whether sleep duration and subjective sleep quality are associated with risk for developing Parkinson’s disease (PD). This research is significant because Parkinson’s disease is prevalent among the elderly, and in many people, symptoms like shaking don’t emerge until years into the neurodegeneration. Hopefully, one day a sleep assessment question might identify individuals who need more screening and/or are candidates for interventions designed to ward off the disorder.
The findings described in the NewsMedical article are based on an enormous Chinese population study named the CHARLS (China Health and Retirement Longitudinal Study). The primary question being addressed here is whether not getting enough sleep or self-reported quality of sleep is linked to an increased likelihood of being diagnosed with PD and whether combinations of sleep measurements may help predict the risk of PD in middle-aged and older individuals.
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Sleep Quality in Developing Parkinson’s Disease
At the centre of everything is the connection between sleep and Parkinson’s disease (PD). PD is a neurodegenerative disorder, which is a disease that damages cells in the brain over time, ultimately causing problems with movement and other systems in the body, including sleep issues. Many people who have already received a diagnosis of PD experience sleep issues, but researchers think that people who develop a PD diagnosis years later have trouble with sleep, which can be an indication of the disease and may even be a precursor to its development.
At a very basic level, the question being answered is whether adults who are midlife and older and consistently short-sleep and/or report having low-quality sleep are at a greater risk of being diagnosed with PD as they get older compared to those who sleep more and have good-quality sleep. The team examined a few key sleep indicators: number of hours sleeping per night, sleep quality assessment by each person, and amount of time they spent napping, and correlated this to the diagnosis status of PD.
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Research Background
Using data from the CHARLS cohort, a major long-running survey of Chinese adults who are middle-aged and elderly, researchers first conducted an initial cross-sectional analysis on 2020 CHARLS data, with 16,403 participants remaining after removing those who were missing information about their Parkinson’s status, personal traits, farm activity, or sleep factors. Next, the authors carried out a longitudinal study (follow-up analysis) of people who entered the study in 2011.
2013, 2015, and 2020 waves of CHARLS data were used, and individuals who had a diagnosis of dementia or other cognitive diseases like PD at the outset of the study and possessed full sleep data and background information were included, leaving them with 8,624 individuals to analyse.
Sleep duration, self-reported sleep quality, and nap duration were obtained using the health status module of a health status questionnaire. Various background characteristics, such as age, sex, marital status, place of residence (urban/rural), smoking, alcohol consumption, occupation (farming in some parts of the analysis), and level of education (in parts of the analysis), were also collected. To investigate sleep and PD, we applied the following statistical techniques: logistic regression models to predict odds of developing PD according to category of sleep; LASSO regression to identify sleep characteristics that best predict PD; and restricted cubic splines analysis to test for a nonlinear association between sleep duration and PD risk. For cohort analysis, participants were divided into four quarters (Q1-Q4) of average sleep duration and no present self-reported sleep disturbances, and we observed whether they subsequently developed PD.
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Sleep Quality and Sleep Pattern as Predictors of Parkinson’s Disease
Out of 275 people in the 2020 cross-sectional sample, questionnaire responses identified them as having PD. Only a tiny proportion of PD cases slept for over 9 hours. Over half had between 4 and 7 hours, and short sleep of 4 hours or less increased the risk of having PD by more than double in the reference group who had 7-9 hours of sleep. The 2 strongest predictors of PD included sleep duration, sleep quality, and a group of other measures, although age and sex were significant factors too
The splines suggested a linear association for people 60 and younger, with the risk for PD decreasing as sleep length increased, whereas in the older age group, the association was curvilinear, and the pattern looked like a “U” shape, with the highest estimated risk at approximately 5.2 hours of sleep. In the longitudinal study population, there were 97 cases of PD (about 1.12% of the incidence rate), with shorter-than-average sleep but without self-reported problems (Q1) having the lowest incidence and shorter-than-average sleep with problems (Q3) the highest.
A statistically significant disparity in PD incidence rates between those in Q1 and Q3 was evident, suggesting that the risk might be substantially increased by poor sleep quality. In individuals with a sleep disorder, incidence rates were more concentrated among the younger cohort (age <= 60) compared to the older group, and sex-based disparities differed based on the presence/absence of sleep problems and duration of sleep.
Author’s Insight
In the researchers’ opinion, the main message to the reader is that sleep duration and quality, on the self-report, are “substantively associated with PD risk, particularly among middle-aged and younger-old participants.” According to the investigators, the negative relationship found between sleep duration and PD risk among those 60 years or younger “indicates that chronically short sleep could represent a targetable risk factor or vulnerability marker, whereas the U-shaped relationship among older participants suggests that both very short and too-long sleep could increase risk with age. “In addition, the observation that the combined presence of short sleep and poor sleep quality highlights a subgroup of subjects with substantially elevated incident risk for PD provides evidence that a multidimensional assessment of sleep characteristics may provide greater insight into PD pathogenesis.”
The study also has some key weaknesses pointed out by the authors. The PD status was derived from questionnaires and not confirmed by medical records, meaning there could be misclassification bias. The sleep durations and quality were self-reported, which can be an underestimate or overestimate compared to objective data. Additionally, the study was on a Chinese middle-aged population and older people; therefore, the findings could not perfectly extend to other ethnic groups. Due to it being an observational study, there is a risk that early stages of PD cause an alteration in the brain that would affect the quality of sleep many years before PD diagnosis and would thus not be a causal relationship. Nevertheless, the researchers acknowledge these limitations. Even so, they suggest that this type of testing could provide an inexpensive first step in the initial risk stratification of PD patients.
Read More: What is Parkinson’s Disease How to cope with it?
Conclusion
Taken together, the findings suggest that sleep duration and self-rated sleep quality can predict the risk of having and developing PD. This was observed in a large community-based Chinese population. A high risk of PD is predicted by extremely short sleep duration. Among people aged about 60 years or younger, the risk is also associated with a combination of short sleep and poor sleep quality. In older adults, the relationship follows a more U-shaped pattern. Although sleep variables alone have limited value in predicting risk, combining sleep duration and sleep quality improves prediction. Together, they provide greater predictive power.
This offers an exciting prospect. Sleep could be a valuable indicator of brain health. It may also help identify the potential for developing a neurodegenerative disease. The study was small. It did not measure sleep using definitive markers. It also did not include participants with a confirmed PD diagnosis. Nevertheless, more large-scale studies with precise diagnostic measures are needed to confirm these findings. Incorporating sleep evaluation into risk assessment for PD could also offer early warning signs.
References +
Sai Lomte, T. (2026, July 7). News-Medical. News-Medical. https://www.news-medical.net/news/20260706/short-sleep-and-poor-sleep-quality-track-with parkinsone28099s-risk.aspx
