What causes occasional involuntary intakes of breath?

Everyone occasionally takes a somewhat deeper breath in order to open areas of the lung that close when a deep breath is not taken. This allows more oxygen to be inhaled and more carbon dioxide to be exhaled. If your breathing becomes uncomfortable or you feel like you cannot get enough air, you should see a doctor ASAP. Good luck to you!

Usually an occasional gasp of a breath is a benign occurrence caused by a transient spasm of the diaphragm, a diaphramatic hiccup so to speak. This is much different from the shortness of breath with exertion which often indicates a pulmonary or cardiac problem

Agree with Dr. Ferranti. Occasional deep breaths, sighs, are a physiological phenomenon and is essential for keeping the air-exchanging part of lung, alveoli, open. Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.