Activate the Healing Power of the Vagus Nerve: 2 Books in 1: Vagus Nerve and The Polyvagal Theory. The Complete Guide to Treat Anxiety, Stress, Depression and other Chronic Diseases. Updated version Kindle Edition

This book is poorly written with spelling and grammatical errors, as well as poor style. It attributes practically any physical or mental health condition on low vagal tone. I'm sorry, but e.g. personality disorders are definitely NOT caused by low vagal tone. This book basically promises a miracle cure for complex psychological and physical health problems without giving concrete scientific evidence. And no, "some people say so" is not scientific evidence. I'd recommend not wasting your money on this.