Why do we sneeze | What you need to know

Let’s be clear. Sneezing, what is it and why do we sneeze? Sneezing is one of the many defensive mechanisms of the HUMAN BODY against infectious or irritating agents that come into contact with the first airways. It is a nasal nervous reflex, an involuntary and automatic response of the body to a precise stimulus. Inside the nasal pits, the palate and the pharynx there areĀ  specific receptors capable of detecting the presence of potential threats, such as dust, pollen or small foreign bodies.

If stimulated beyond a certain threshold, they send electrical impulses to specific areas of the brain through the trigeminal. These brain areas, process the nerve signals received and organize a response, giving rise to sneezing. Sneezing is always preceded by one or more deep inhalations that allow be stored in the lungs a large reserve of air .

How many times do you sneeze

Why do we sneeze several times before you can finally feel your nose free? According to science, a particularly irritation can be expelled after three sneezes. So why do we sneeze and why three times? Sneezing is a very powerful emission of air from the lungs, which travels at about 160km/h and emits between 2,000 and 5,000 bacteria, which occurs after an allergic reaction or irritation of certain particles. It happens in fact, that we sneeze because a respiratory infection (the cold for example), because you have caught cold. In the presence of allergens (such as pollen or animal hair) or other irritants (such as smoke, pollution, dust or mold).

Irritants are not the only agents to cause the reaction of sneezing, some people in fact suffer from sneezing reflex, which consists in sneezing after strong sources of light. To be clear, when it comes to sneezing and look a light to speed up the process. And now let’s come to the “why do we sneeze three times”. To properly expel an irritant agent, first you have to move it from the nose (first sneeze), then you have to bring it to the tip of the nose (second sneeze), and then throw it out (third sneeze).

Bright light

Why do we sneeze at the sight of the bright light? Sneeze at the sight of the bright light is a phenomenon thatĀ involves 15-30% of the population and science has given three types of explanations to motivate the strange correlation “light sneezing”.

1: First hypothesis is based on the awareness that exposure to the sun activates the part of the nervous system responsible for involuntary actions. As well as in front of a flash, instinctively we close the eyes, the same applies to the sun. Spontaneously you could sneeze at the sight of sunlight or artificial light. But not everyone does. Experts believe that the reaction to sneezing is a genetic question.

2: Another reason why do we sneeze, is the trigeminal optic nerve. Which controls some facial movements. The brain could easily exchange the luminous stimulus as an irritant of the nose, and respond accordingly with a sneeze.

3: Another study showed that the visual cortex of those who sneeze in the light is much more sensitive than others who are not affected by the same phenomenon. Sneezing derived from the sight of light, would therefore be an even deeper reflection.

The eyes

Why do we sneeze and why we close the eyes? It may seem like a trivial question, but the mechanisms that trigger, involving the different muscles of our body, are many. Sneezing starts when the nerve sensors in the nose signal the presence of foreign particles. This is how “the emergency” is activated. The nose emits mucus, the respiratory muscles strongly compress the chest and those that control the respiratory tract close them. When the air pressure in the lungs becomes too high. The airways open and expel air and foreign particles.

The spasm that accompanies the sneezing involves several muscles, including the facial ones, responsible for the fluttering of the eyes. Closing your eyes by sneezing is probably a biological mechanism that serves to protect them. Ejecting the particles from the nose requires a pressure that turns into “high speed of expulsion”. Closing your eyes, then, can help prevent this pressure from damaging your tear ducts. The solicitation of a sneeze leads to inhale about 2.5 liters of air, which creates in our lungs an increase in pressure. Uvula and also the palate react by lowering and directing the air towards the nose.


It is good to give free rein to the sneeze, avoiding suffocating it by keeping your mouth closed. If we keep the mouth closed during the sneezing, you have a strong increase of pressure inside the body, which has negative repercussions at the level of the eyes, the nose, the ears, the diaphragm, the cervical tract and the brain. Up to cause haemorrhages. Although this risk is low for healthy people, it becomes more significant for those with vascular malformations . For this reason, the advice is to always avoid in any case to close your mouth by sneezing.