There is a clear connection between stress and hypertension. Learning to manage stress is part of a comprehensive treatment of hypertension. One of the four suggestions American Heart Association makes to manage stress is a daily program that involves ten minutes deep breathing. The terms deep breathing without a basic understanding of anatomy could be confusing and counter productive.
The primary confusion in deep breathing is in the role the diaphragm muscle plays in deep breathing vs the role your chest plays. Your diaphragm is responsible for about half of your breathing volume. Imagine that a single dome shape muscle responsible for half of your breathing capacity.
The rest of your breath comes from external intercostal muscles,internal intercostal muscles, scalene muscles, sternomastoids, alae nasi, rectus abdominus, internal and external obliques, transversus abdominus and other small muscles in the neck and head.
When the illusion of deep breathing focuses your attention to upper chest movement you begin to use all the muscles that move the chest. That takes a lot of energy and the return does not even come close to learning true deep breathing that happens by focusing on belly breathing which engages your diaphragm.
Breathing patterns that help you use and strengthen your diaphragm are among the most effective patterns for relaxation.