While sighs are often attributed to sadness, anger, frustration, and angst, research indicates that sighing is a natural part of pulmonary function. The average person sighs twelve times per hour, and without the one sighs the air sacs inside of the lungs would cave, resulting in death. As dramatic as the anatomical explanation for sighing is, the act of heaving in and out can be an effective coping mechanism. Take a look here to see what happens to your mental and physical health when you take a deep sigh.