Astrocyte-centered temporal resilience at the brain-behavior-immunity interface: sleep-circadian disruption and perioperative cognitive vulnerability in older adults

Perioperative cognitive vulnerability in older adults reflects interactions among inflammatory stress, altered brain state, sleep-circadian disruption, and recovery capacity. This narrative review examines astrocyte-centered temporal resilience as a hypothesis-generating framework for integrating these brain-immune-behavior processes. Astrocytes participate in sleep-pressure signaling, circadian regulation, neurometabolic support, inflammatory responses, extracellular homeostasis, and clearance-related physiology; however, these functions operate within broader neuronal, microglial, vascular, endocrine, and environmental networks. Aging may reduce the temporal precision and adaptive range of these interacting systems, thereby limiting recovery after surgical and anesthetic stress. Postoperative delirium, delayed neurocognitive recovery, and postoperative neurocognitive disorder may therefore partly reflect impaired re-coordination of sleep-circadian, immune, metabolic, and behavioral processes, although direct evidence for an astrocyte-specific causal pathway in perioperative populations remains limited. We synthesize evidence concerning astrocytic clocks, inflammatory-metabolic stress, sleep fragmentation, circadian misalignment, anesthesia-induced sleep-like states, glymphatic and aquaporin-4-related physiology, and hospital time ecology. We also distinguish mechanistic evidence from associative clinical findings and consider whether perioperative chronodisruption acts as a mediator of later cognitive vulnerability, a marker of pre-existing susceptibility, or both. The term "astrocyte-centered" is used as an organizing perspective rather than to imply exclusive cellular causation. This framework is intended to guide future studies of temporal phenotyping, intervention timing, and exploratory immune-temporal-behavioral target engagement rather than to define currently validated clinical biomarkers or treatment strategies.