Is Sighing a good or bad habit?

Sighing Should Be Refreshing!
Until we learn to breathe correctly, we could often find ourselves sighing or yawning. This is the body's reaction to a lack of oxygen. To remedy the situation (and improve ones' state of mind) either take a deep abdominal breath IN through the nose and exhale through the mouth or sigh consciously. This "sighing or yawning" should not be confused with being tired.
This is how you can turn the sighs and yawns into a relaxing, mind calming experience. Without particularly thinking about inhaling, just let yourself sigh deeply. As you do this, let the air rush out of your lungs as you let out a sound of deep relief and then simply let the air come back in naturally through the nose. It is particularly helpful if you do this up to a dozen times or more, encouraging yourself to feel completely relaxed. As you do deep abdominal breathing on a regular basis, however, you are less likely to sigh a lot.