Ambulatory blood pressure monitoring (ABPM) enables repeated nocturnal measurements during polysomnography (PSG) but may itself disturb sleep and electroencephalographic (EEG) signals. We investigated cuff-centered EEG activation, AASM-defined arousal, and sleep-stage stability using laboratory-acquired two-night PSG data. Seventy-two participants wore ABPM on Night 1 or Night 2 (n = 36 per randomized sequence); demographics and two-night mean sleep indices were comparable (all p ≥ 0.07). To reduce first-night effects, acute EEG analysis was restricted to 34 participants monitored on Night 2 and 322 measurements initiated during stable sleep without baseline arousal. Mean C3-A2/C4-A1 EEG was compared between the 30-s pre-cuff epoch and the approximately 2-min cuff interval after measurements were averaged within participants. Relative delta power decreased from 0.719 to 0.688 (mean difference, -0.0301; p = 0.0061; dz = -0.50), whereas theta did not change significantly (0.119 to 0.110; p = 0.0632). Alpha, beta, and gamma increased from 0.0696 to 0.0916, 0.0593 to 0.0880, and 0.00951 to 0.01890, respectively (all p < 0.0001; dz = 0.86, 0.96, and 0.77). Stage/arousal analysis included all 72 participants and 893 cuff measurements, of which 655 began during sleep. Arousal accompanied 395/655 sleep-onset measurements (60.3%), while the starting stage was preserved in 561/655 (85.6%). Arousal was most frequent in REM (71.5%) and least frequent in N3 (52.2%); 344/395 arousal-positive measurements (87.1%) retained the underlying stage. Thus, cuff inflation was associated with transient high-frequency EEG activation and frequent arousal, usually without a scored stage transition. Because no sham-inflation control was available and transition proportions were event-weighted, causal interpretation and between-person generalizability remain limited. Cuff-related intervals should be annotated or modeled in PSG analyses, and cuffless monitoring should be considered when uninterrupted sleep physiology is essential.