A large cohort study in China suggests that sleep patterns, particularly short sleep duration and poor sleep quality, may help identify people at increased risk of Parkinson’s disease before clinical diagnosis.
Research: Sleep and Parkinson’s Disease: A population-based study from the CHARLS cohort. Image credit: Lightspring / Shutterstock
In a recent study published as a magazine article, npj parkinson’s diseaseresearchers investigated the association between sleep and Parkinson’s disease (PD) risk.
PD is the second most prevalent neurodegenerative disease after Alzheimer’s disease (AD) and primarily affects older adults. In addition to motor symptoms, PD patients often experience non-motor symptoms such as sleep disturbances, which affect up to 75% of patients. The severity and prevalence of sleep disorders increases with age. Nevertheless, research on the multifaceted effects of sleep disturbances in PD patients remains limited.
About research
In this study, researchers examined the association between sleep and PD risk. The 2020 dataset of the China Health and Retirement Longitudinal Study (CHARLS) was used for cross-sectional analysis, excluding individuals with missing information on PD, demographics, agricultural work, and sleep. The cohort analysis included CHARLS participants from the 2011, 2013, 2015, and 2020 cycles.
Cohort analyzes excluded those with memory-related diseases, including PD, at baseline, and those without data on sleep, farming, demographics, and these diseases. Sleep indicators, including sleep duration, self-reported sleep quality, and nap duration, were assessed using the Health Status (III) module of CHARLS. Information on sociodemographic and health-related covariates was also collected.
Covariates included age, gender, marital status, place of residence, smoking status, alcohol intake, nap time, and agricultural work engagement. Although educational attainment was reported in the cohort baseline table, educational attainment was excluded from adjusted analyzes in 2020 due to high missingness rates. Group comparisons were performed using the chi-square test. The association between sleep duration and sleep quality and PD was assessed using a logistic regression model. Additionally, we performed least absolute shrinkage and selection operator (LASSO) regression to identify sleep metrics most strongly associated with PD.
Restricted cubic spline (RCS) analysis was performed to assess the nature of the association. Subgroup analyzes were conducted by age, gender, marital status, place of residence, alcohol consumption habits, and agricultural activities. Additionally, we calculated PD incidence rates and assessed group differences in these rates. Finally, we used logistic regression models for sleep quality, sleep duration, and both to determine the predictive performance of sleep metrics on PD.
Survey results
The cross-sectional analysis included 16,403 CHARLS participants. Most participants were female (53.1%), cohabiting (76.9%), non-smokers (61.2%), and non-drinkers (63.4%). Overall, 275 people were classified as having PD based on information obtained from the CHARLS questionnaire, of which only 1.8% reported sleeping 9 hours or more, and 54.2% slept 4 to 7 hours. Furthermore, 40.7% of participants classified as having PD rarely or never reported sleep deprivation, whereas 24.4% reported sleep deprivation most of the time.
Among non-PD subjects, most slept between 4 and 7 hours (59.3%), with only 3.5% sleeping more than 9 hours. Logistic regression analysis showed a non-significant point estimate of lower PD risk in people who slept 9 hours or more compared to people who slept 7 to 9 hours (Reference). PD risk was similar between the 4-7 hours sleep group and the reference group, but was significantly higher in the 4-hour or less sleep group.
Among the sleep measures assessed, sleep duration and sleep quality were most strongly associated with PD. Age and gender also emerged as relevant exposure factors in the model. RCS analysis showed a significant linear relationship between sleep duration and PD risk in people under 60 years of age, but a nonlinear relationship in people over 60 years of age. The cohort analysis included 8,624 participants, grouped into four categories (Q1-Q4) based on sleep quality and sleep duration. Most of these participants (89.3%) were 60 years of age or older.
The Q1 group included participants who slept below average but did not self-report sleep problems. Q2 included people who slept longer than average but did not self-report having sleep problems. Q3 included subjects with below-average sleep duration and self-reported sleep problems. Q4 included those who slept longer than average and self-reported sleep problems. In this cohort, 97 PD cases were recorded, with an incidence of 1.12%.
PD incidence was lowest in the Q1 group and highest in the Q3 group. A significant difference in PD incidence was observed only between the Q1 and Q3 groups. Among participants with sleep disorders, the incidence of PD was higher in participants younger than 60 years than in those older than 60 years, but gender-specific patterns differed by sleep status and sleep duration. The sleep duration model achieved an area under the receiver operating characteristic curve (AUROC) of 0.59 for predicting PD, whereas the AUROC of the sleep quality model was 0.62. Incorporating both sleep quality and sleep duration into a single model increased AUROC to 0.64, but overall predictive performance remained modest. Although the combined model was significantly better than sleep duration alone, sleep quality alone was not.
conclusion
In summary, both sleep duration and sleep quality showed significant associations with PD risk. It was found that sleep duration was negatively correlated with PD risk, and in people under 60 years of age, the longer the sleep duration, the lower the PD risk. In contrast, a U-shaped relationship between sleep duration and PD risk was observed in older adults aged 60 and older, with the highest risk after 5.2 hours of sleep. However, this finding is observational and cannot establish a causal relationship. PD status was inferred from questionnaire items rather than confirmed clinical records, and sleep measurements were self-reported, which may limit generalizability in a cohort of middle-aged and older Chinese adults. Overall, sleep assessment and management may be a promising target for strategies aimed at early risk stratification and preventive sleep health management in PD.
