For older adults with disabilities and aphasia, timely care remains challenging, particularly during the 8-h nocturnal period, creating a need for stable non-invasive EEG interfaces for assistive brain-computer interface (BCI) applications. Asynchronous steady-state visual evoked potential (SSVEP)-based control provides a practical strategy for nighttime assistive care, but its performance is largely constrained by the electrode interface. Here, we developed a comb-shaped, silicone-scaffolded PVA/SA/PEDOT:PSS hydrogel electrode for stable overnight EEG acquisition on hair-bearing scalp regions. The PVA/SA network provided soft and compliant contact, while PEDOT:PSS improved interfacial charge transfer. The comb-shaped silicone scaffold further enhanced conformal contact and effectively suppressed hydrogel dehydration. The electrode maintained stable scalp impedance for 8 h and enabled reliable EEG recording on both hairless and hair-bearing scalp regions. When used in an asynchronous SSVEP-based intelligent assistive care system, it achieved 100% triple-blink (three consecutive blinks) detection accuracy for system activation and 97.3 ± 0.4% SSVEP classification accuracy for command selection, with stable performance throughout the 8-h monitoring period. Cytotoxicity assays indicated no obvious cytotoxicity under the tested conditions, and comfort evaluations supported good wearability. This hydrogel electrode provides a promising approach for non-invasive and reliable overnight EEG acquisition and shows potential for BCI-assisted nighttime care.