Impact of sleep quality on the quality of life of patients with Parkinson's disease: a questionnaire based study

Objective: Poor sleep quality contributes to the inferior quality of life of patients with Parkinson's disease (PD) despite appropriate treatment of motor symptoms. The literature about the impact of sleep quality on quality of life of patients with PD is as yet sparse. Material and methods: One hundred patients of PD diagnosed as per UK Brain Bank criteria were assessed for severity and stage of PD using UPDRS and modified Hoehn &Yahr scales. The quality of sleep was assessed by Pittsburgh Sleep Quality Index and excessive daytime somnolence (EDS) was evaluated using Epworth Sleepiness Scale. Parkinson's Disease Questionnaire 39 (PDQ-39) was used to determine quality of life of the patients. Comorbid depression and anxiety were assessed using Inventory of Depressive Symptoms-Self Rated and Hamilton Anxiety Rating Scale. Pearson's correlation and multiple linear regressions were used to analyze relation of sleep quality with quality of life of patients. Results: Fifty patients had poor sleep quality. EDS was present in only 9 patients. Co-morbid depression and anxiety were present in 52 and 34 patients respectively. While the motor severity assessed by UPDRS-III was observed to adversely affect quality of life, it did not negatively impact quality of sleep. Higher score on UPDRS-total and UPDRS IV suggesting advanced disease correlated with poor sleep quality. Depression and anxiety were significantly more frequent in patients with poor sleep quality (p < 0.01). Patients with poor sleep quality had worse quality of life (r = 0.338, p < 0.05). Depression and anxiety were also observed to have significant negative impact on quality of life of PD patients (p < 0.01). Poor sleep quality was not found to be an independent predictor of quality of life using multiple linear regression analysis. Conclusion: Poor sleep quality along with comorbid depression, anxiety and advanced stage of disease is associated with poor quality of life. (C) 2016 Elsevier B.V. All rights reserved.