Anger often acts as a pressure gauge for stress you haven't been able to...

https://iris-wiki.win/index.php/The_Gap:_Mastering_Your_Anger_Before_It_Masters_You

Anger often acts as a pressure gauge for stress you haven't been able to release. When it builds up, you might notice a tight jaw or shoulders that never seem to drop. You might even find yourself staring at the ceiling when you need sleep most