Brain Preparedness for Active Forgetting: Cortisol Awakening Response Proacts Prefrontal Control Over Hippocampal-Striatal Circuitry

Stress-related psychiatric pathologies (e.g., rumination in depression, intrusive memories in PTSD) involve impaired inhibitory control over emotional memories and disrupted cortisol circadian rhythms. However, how these mechanisms interact to support adaptive forgetting remains unclear. Here, by integrating multi-modal neuroendocrine profiling with fMRI-based memory suppression in 90 participants, we demonstrate that the cortisol awakening response (CAR)--a circadian surge priming the brain for daily demands--proactively and selectively enhances suppression of recently acquired but not overnight-consolidated emotional memories. This time-dependent facilitation manifests through dual neural mechanisms: Robust CAR broadly amplifies dorsolateral prefrontal cortex (dlPFC) engagement during suppression attempts and specifically strengthens top-down dlPFC control over hippocampal-striatal circuits exclusively for recent traces. Our findings bridge circadian biology, systems neuroscience, and clinical psychopathology to establish CAR as a neuroendocrine preparedness mechanism that proactively configures adaptive forgetting circuits across sleep-wake cycles, thereby informing circadian-based interventions for stress disorders.