Insomnia blocks fear extinction via tonic arousal

A PLOS Mental Health study using skin‑conductance models found that people with insomnia show elevated background (tonic) electrodermal activity that persists after a learned threat is removed, and this elevated baseline predicts poorer formation of the inhibitory "safety" memories that extinguish fear. That suggests insomnia doesn’t just make people tired — it alters the physiological arousal backdrop that helps (or hinders) emotional learning and therapy. — If insomnia impairs fear‑extinction, clinicians and public‑health programs must account for sleep in designing and delivering anxiety treatments and prevention, and policymakers should recognize sleep disorders as a multiplier of mental‑health burden.