Sleep Dysfunction in Parkinson's Disease

Sleep disorders are common in Parkinson's Disease (PD). It can antedate the motor manifestations of PD. It is related primarily to the involvement of sleep regulating structures, secondary involvement through motor, depressive and dysautonomic symptoms and the tertiary involvement through anti-parkinsonian medications.

The aim of our study is to evaluate the frequency and nature of the sleep abnormalities in Idiopathic Parkinson's Disease, analysing the sleep architecture using polysomnography and to correlate the results with the disease parameters.

A cross-sectional study was done in 50 patients who fulfill the "UK Parkinson's Disease Society Brain Bank Clinical Diagnostic Criteria". They were assessed using detailed history and clinical neurological examination. The severity of the disease was assessed based on Unified Parkinson's Disease Rating Scale (UPDRS part III) and the sleep is assessed using Parkinson's Disease Sleepiness Scale (PDSS) and Epworth Sleepiness Scale (ESS). Objective sleep study was done using polysomnography.

Disturbed sleep was reported by 70% of patients. Sixty percent of them had difficulty in falling asleep and 48% had difficulty in maintaining the sleep due to frequent awakenings. Day time somnolence was reported by 30% of patients. Polysomnographic analysis showed reduced total sleep time in 40 patients (80%). Correlation analysis of the total sleep time, sleep efficiency, deep sleep time, REM sleep time with the disease duration, staging, severity, PDSS Score, showed significant positive correlation (p<0.05). Sleep related movement disorders like Periodic Limb Movements (PLMS), Restless Leg Syndrome (RLS) also showed inverse correlation with disease duration and severity (p<0.05).

Sleep architecture is markedly disturbed in patients with Idiopathic Parkinson's disease. There is a reduction in the total sleep time, deep sleep time and REM Sleep duration. Periodic limb movements in sleep, restless leg syndrome, and obstructive sleep apnea contributes to the sleep fragmentation resulting in defective day time functioning.