Did you know that, like humans, animals also sneeze? Yes, they do. Observed in living beings, sneezing is a reflex action (something that the body does of its own accord) and is as natural as blinking our eyes - involuntary and uncontrollable.
But have you ever given thought to what triggers sneezing? Before we look for answers to questions like why do we sneeze when we have a cold or what makes us sneeze, let us first try to understand what exactly is a sneeze.
What is a Sneeze?
A sneeze is a convulsive or a spastic expulsion of air from the lungs, channeled through the nose and mouth. Since it is a semi-autonomous action, a person cannot hold it back, stop it, or control it in any way. It is often the result of an irritated nasal mucous membrane or discomfort in the chest or pharynx, which connects the esophagus and nasal cavity.
When the nerve endings in the nose lining detect the presence of foreign matter or other unwanted substances, an impulse is sent to the part of the brain responsible for controlling involuntary actions, which triggers a sneeze.
What Triggers Sneezing?
The nose works as an air purifier for the human body. The air (which may consist of bacteria, stimulants, and other foreign materials) that enters the human body is cleansed by the nose. A person sneezes if foreign particles irritate the nasal mucosa.
In other words, sneezing is actually one of the body's ways of expelling harmful substances that have forced their way into the body. This action may be triggered because of a number of stimulants like a viral infection, pollen, animal hair, perfume, cold air, smoke, dust, or anything which can irritate the nasal passage.
There are chances that the body might misinterpret an irritant. This mostly happens in case of allergies. For ex: the body assumes that a pollen grain, although harmless, is trying to attack the body. To defend itself from the plausible harm of the allergen, the body releases histamine which expels the pollen grain from it, and the person starts sneezing.
Some people start sneezing as soon as they step out in the sun. According to a research, 1 out of 3 people sneeze when they are exposed to bright light. Such people are called photic sneezers. It is a hereditary condition, which runs in the family.
So why do we sneeze when we have a bad cold? The nasal passages of a person who has a cold are blocked. Sneezing clears up these blocked passages and allows flow of fresh air into the system. The body also uses this mechanism to expel and get rid of unwelcome germs and bacteria. Not sneezing might prevent them from leaving the body and lead to an infection.
The occasional sneeze is not a problem, that's just the body's routine to steer clear of bacterial germs and foreign substances. Continued sneezing for an extended period is not something to be surpassed, you should bring it to the notice of a health care professional immediately, find out what's causing the unstoppable sneezes and nip the cause in the bud.