Does the Number of Turns during Sleep Have Utility in the Early Detection of Parkinson's Disease and Its Related Disorders?

Introduction: Patients with Parkinson's disease (PD) and its related disorders exhibit decreased sleep activity. However, the factors associated with this decreased sleep activity remain unknown. Thus, we aimed to explore the factors associated with sleep activity in patients with PD and its related disorders.Methods: This study included 33 patients with PD and its related disorders and 57 healthy participants who visited our outpatient clinics between November 2018 and March 2020. We evaluated the patients' muscle masses and measured the number of times they turned during sleep. The limb skeletal muscle index was utilized to evaluate the loss of muscle mass. This study was registered in the UMIN Clinical Trials Registry (Clinical Trials Registry number: UMIN000052436).Results: Age, maximal grip strength, presarcopenia, phase angle (legs), history of hypertension, diabetes mellitus, dyslipidemia, orthopedic diseases, and the number of turns during sleep were associated with PD and its related disorders. The number of turns was independently associated with PD and its related disorders. Receiver operating characteristic curve analysis revealed that the cutoff value for the number of turns was 6 (area under the curve, 0.986; sensitivity, 93.9%; specificity, 96.5%). The cutoff numbers of turns for men and women were 9 and 6, respectively (area under the curve, 1.0 and 0.981; sensitivity, 100% and 94.7%; specificity, 100% and 95.2%; respectively).Conclusions: The number of turns during sleep is significantly associated with PD and its related disorders and may decrease before patients present with sarcopenia. In addition, PD and its related disorders may coexist in men who turn less than nine times during sleep.