Perimenopause doesn't just affect your hormones — it rewires your autonomic nervous system. Declining estrogen weakens the parasympathetic "brake" on your fight-or-flight response, leaving sympathetic activity elevated. Research links this shift to heart palpitations, poor sleep, anxiety, and the constant sense of being on edge. Cathy explains the science of perimenopause nervous system dysregulation and shares what the evidence actually supports for restoring balance.