Sleep plays a critical role in synaptic regulation, memory consolidation, and neural recovery. According to the Synaptic Homeostasis Hypothesis (SHY), delta-band activity (typ- ically 1–4 Hz) during non-REM (NREM) sleep reflects a homeostatic process of synaptic downscaling, characterized by a progressive decline across the night. While previous studies have focused on delta power as an index of sleep pressure, the present work targeted a slower spectral component—slow oscillations (SO, <1.5 Hz)—to investigate their topographic modulation and potential sensitivity to neurodegeneration in Parkinson’s disease (PD), where sleep regulation may be disrupted. Sleep-related cortical dynamics were analyzed in four groups by exploiting high-density EEG recordings: healthy controls (CTL), drug-naive patients (DNV), advanced patients without dyskinesias (ADV), and patients with levodopa-induced dyskinesias (DYS).