The Complex Science Behind the Common Sneeze

A sneeze is an uncontrollable, sudden, and sometimes loud emission of air through the nose and mouth. Although it is a common occurrence, the medical community knows very little about sneezing. What they do know is that sneezing — or sternutation — is not only a reflexive act but a protective one. Specific environmental triggers lead to sneezing, as do specific causes originating in the central nervous system. Everyone has their own sneezing pattern, which is as individualistic as their fingerprints.

1. The Two Phases of Sneezing

Sneezing is a reflex that protects the nose from foreign objects, preventing access to the lungs and other organs. There are two phases:

• The first phase — the nasal or sensitive phase — begins when the chemical or physical irritants stimulate the mucosa.
• The second phase, also called the efferent or respiratory phase starts with the eyes closing, followed by a deep inhalation and a forced exhalation. The glottis, an elongated space between the vocal cords, closes. Intrapulmonary pressure increases, the glottis dilates, and the air explodes through the nose and mouth.