This is a great one-page explanation of the effect of trauma on the Vagus nerve and how that nerve continues to react to stimulus even when no real danger is present. An overview with added bonus of a short yoga practice to help us learn to reset our systems when we feel threatened.

https://drarielleschwartz.com/vagus-nerve-yoga-for-trauma-recovery-dr-arielle-schwartz/#.YCE9S5NKgWo