This breathing exercise can be called box breathing, battle breathing, bomb breathing, or can exist by a few other names. It's a very simple breathing exercise that people that can be used by those who disengage bombs. They use this technique to manage their stress at a level where they are able to make decisions, and function optimally under extreme levels of stress.

This is a great technique to control those ruminating thoughts while attempting to fall asleep. The practice is pretty simple: Breathe in for the count of four, hold your breath for the count of four, breathe out for the count of four, hold for the count of four, and repeat.