We compared the sleep structure including a quantitative electroencephalographic (EEG) analysis and the frequency of periodic limb movements (PLM) in 17 patients with Parkinson's disease (PD; 10 men, seven women, mean age 65.9 years, mean Hoehn and Yahr stage 1.8) who had never been treated with dopaminergic agents (de novo), and 10 healthy controls (six men, four women, mean age 64.5 years). The REM sleep EEG of the PD patients was characterized by a sustained increase in the high-theta/alpha (7.8–10.5 Hz) frequency range during the first one-third (i.e., 11.00 p.m. to 01.40 a.m.) of the night. There was no significant difference in the sleep continuity and sleep architecture as well as in the PLM index between both groups. The analysis of the temporal dynamics of the observed changes suggests a dysregulation of the REM sleep homeostasis in the patients with PD. © 2001 Movement Disorder Society.