Shallow breathing

Shallow breathing is the drawing of minimal breath into the lungs, usually by drawing air into the chest area using the intercostal muscles rather than throughout the lungs via the diaphragm. Shallow breathing can result in or be symptomatic of rapid breathing and hyperventilation. Most people who breath shallowly do it throughout the day and are almost always unaware of the condition.

Shallow breathing is considered unhealthy, the better alternative being diaphragmatic breathing.

Conditions
Several conditions are marked by or symptomatic of shallow breathing. The more common of these symptoms include: various anxiety disorders, asthma, hyperventilation, pneumonia, pulmonary edema, and shock. Anxiety, stress, and panic attacks often accompany shallow breathing.

Sometimes it can be caused by fear and is accompanied by sweaty palms and a sick feeling in the stomach.