Sneezing: A Universal Reflex with a Unique Impact

Sneezing is a phenomenon that we all experience, yet it remains both universal and uniquely personal. It is an involuntary reflex that serves as a protective mechanism to expel irritants from our nasal passages. During a sneeze, the airway pressure exceeds that of heavy breathing during exercise by more than 30 times. Remarkably, sneezes can travel at speeds ranging from 5 meters per second to over 150 kilometers per hour. While it is possible to halt a sneeze by holding or pressing underneath the nose, experts caution against this practice due to the potential risks associated with stopping a forceful sneeze mid-action.

The initiation of a sneeze occurs when sensory nerves in the nose are triggered by various irritants, such as allergens, viruses, bacteria, or fluids. These sensory nerves transmit this information to the brain, and once a threshold amount of irritant signals is reached, the sneeze reflex is triggered. The sneeze reflex commences with a deep breath intake, followed by the buildup of pressure in the airways. Consequently, the diaphragm and rib muscles contract, leading to the reflexive closing of the eyes and the forceful exhalation that characterizes a sneeze.

During the exhalation of a sneeze, the tongue is lifted to the roof of the mouth, effectively closing the back of the mouth and forcing the air through the nasal passage. This forceful expulsion of air helps to flush out the irritants that prompted the sneeze. The distinct sound “tch” that accompanies a sneeze occurs due to the reflexive touching of the tongue to the roof of the mouth.

The trigeminal nerves, the largest of the 12 pairs of cranial nerves, carry sensory information from the face to the brain. These nerves play a crucial role in carrying touch, pain, and irritation sensory signals from the facial skin, as well as from within the nose and mouth. Within each trigeminal nerve are numerous nerve branches, each carrying distinct types of sensory information. Sensory nerves travel to the brain via the spinal cord, where they interact with interneurons, which serve as the “gates” in the gate control theory of pain.

Narrow nerves carrying pain and irritant signals instruct the interneurons to “open the gate,” allowing the pain signals to reach the brain. On the other hand, larger nerves carrying touch information are capable of “closing the gate” and blocking the transmission of pain messages to the brain. This mechanism explains why rubbing an injured area can reduce pain sensations. Additionally, stimulating the trigeminal nerves through actions like moving the jaw has been found to alleviate tooth pain, supporting the gate control theory.

Numerous suggestions exist for halting or preventing a sneeze by stimulating the trigeminal touch nerves to “close the gate.” These techniques include pulling the ear, pressing the tongue to the roof of the mouth or the back of the teeth, touching the nose, or even inserting a finger into the nose. By stimulating these trigeminal touch nerves, the goal is to impede the irritant signals from reaching the brain and initiating a sneeze. However, when faced with a situation where sneezing may be considered inappropriate, it is essential to consider the potential risks of stopping a sneeze.

Closing the mouth or nose during a sneeze can increase the airway pressure five to twenty times more than a normal sneeze. With no release, this heightened pressure can lead to damage to the eyes, ears, or blood vessels. While the risks associated with stopping a sneeze are relatively low, reported cases of brain aneurysms, ruptured throats, and collapsed lungs serve as cautionary reminders. Therefore, it is advisable to prioritize the prevention of sneeze reflexes by addressing allergies or irritants. If prevention is not possible, it remains prudent to embrace personal sneezing styles and opt to sneeze into a tissue.

Sneezing is an intricate reflex that serves as a defense mechanism against irritants within our nasal passages. Understanding the science behind sneezing, including its biological process and the role of trigeminal nerves, can shed light on ways to control or prevent sneezes. However, it is crucial to prioritize safety and weigh the potential risks before attempting to stop a forceful sneeze.