Most Parkinson's patients complain about sleep problems. The subjective effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on nocturnal disabilities and sleep quality was elucidated by the recently established Parkinson's disease sleep scale (PDSS). The DBS-treated group obtained significant improvement of motor function assessed by the Unified Parkinson's Disease Rating Scale. The mean total PDSS improved significantly after surgery whereas no change was found for the control group. Significant improvements of individual questions were obtained for overall sleep quality and motor symptoms whereas nocturia and daytime sleepiness did not change despite significant reduction of parkinsonian medication.