Sneeze

For other uses, see Sneeze (disambiguation).

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Sneezing can spread disease by launching disease vectors into the air.

A sneeze (or sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa. Sneezing can be triggered through sudden exposure to bright light, a particularly full stomach, or viral infection, and can lead to the spread of disease.

Biological elements

The function of sneezing is to expel mucus containing foreign particles or irritants and cleanse the nasal cavity. During a sneeze, the soft palate and uvula depress while the back of the tongue elevates to partially close the passage to the mouth so that air ejected from the lungs may be expelled through the nose. Because the closing of the mouth is partial, a considerable amount of this air is usually also expelled from the mouth. The force and extent of the expulsion of the air through the nose varies.

Overall mechanism

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1894 Kinetoscope of Fred Ott sneezing, taken by Thomas Edison's laboratory.

Sneezing typically occurs when foreign particles or sufficient external stimulants pass through the nasal hairs to reach the nasal mucosa. This triggers the release of histamines, which irritate the nerve cells in the nose, resulting in signals being sent to the brain to initiate the sneeze through trigeminal nerve network. The brain then relates this initial signal, activates the pharyngeal and tracheal muscles and creates a large opening of the nasal and oral cavities, resulting in a powerful release of air and bioparticles. The powerful sneeze is attributed to its involvement of numerous organs of the upper body – it is a reflexive response involving the face, throat, and chest muscles

A cause of sternutation is sudden exposure to bright light - known as the photic sneeze reflex.

Sneezing is also triggered by sinus nerve stimulation caused by sinus infection and allergies.

A rarer trigger, observed in some individuals, is the fullness of the stomach immediately after a large meal. This is known as snatiation and is regarded a medical disorder passed along genetically as an autosomal dominant trait.

Sneezing cannot occur during sleep due to REM atonia - a bodily state wherein motor neurons are not stimulated and reflex signals are not relayed to the brain. Sufficient external stimulants, however, may cause a person to wake from their sleep for the purpose of sneezing, although sneezing occurring afterwards would take place when partially awake.

Epidemiology

While generally harmless in healthy individuals, sneezes spread disease through the infectious aerosol droplets, commonly ranging from 0.5 to 5 µm. 40,000 droplets can be produced by a sneeze.

Conservative estimates place the speed of release at around 100 mph. However, the data collected from the 147th episode of Mythbusters titled 'Flu Fiction', concluded that the speed is closer to 35-40 mph, and that a sneeze can launch droplets from 15 to 20 feet.

Preventive measures

Examples of preventive techniques are: the deep exhalation of the air in the lungs that would otherwise be used in the act of sneezing, holding the breath in while counting to ten, crinkling the nose and keeping the eyes open, or gently pinching the bridge of the nose for several seconds.

Proven methods to reduce sneezing generally advocate reducing interaction with irritants, such as keeping pets out of the house to avoid animal dander; ensuring the timely and continuous removal of dirt and dust particles through proper housekeeping; replacing filters for furnaces and air-handling units; employing air filtration devices and humidifiers; and staying away from industrial and agricultural zones. Although some people wonder why you would want to prevent a sneeze as they can be very pleasurable.

Historic instances and practices

In Ancient Greece, sneezes were believed to be prophetic signs from the gods. In 410 BC, for instance, the Athenian general Xenophon gave a dramatic oration exhorting his fellow soldiers to follow him to liberty or to death against the Persians. He spoke for an hour motivating his army and assuring them of a safe return to Athens until a soldier underscored his conclusion with a sneeze. Thinking that this sneeze was a favorable sign from the gods, the soldiers bowed before Xenophon and followed his command. Another divine moment of sneezing for the Greeks occurs in the story of Odysseus. When Odysseus returns home disguised as a beggar and talks with his waiting wife Penelope, she says to Odysseus, not knowing to whom she speaks, that "[her husband] will return safely to challenge her suitors"". At that moment, their son sneezes loudly and Penelope laughs with joy, reassured that it is a sign from the gods (Odyssey 17: 541-550).

In Europe, principally around the early Middle Ages, it was believed that one's life was in fact tied to one's breath - a belief reflected in the word "expire" (originally meaning "to exhale") gaining the additional meaning of "to come to an end" or "to die". This connection, coupled with the significant amount of breath expelled from the body during a sneeze, had likely led people to believe that sneezing could easily be fatal. This theory, if proven conclusively, could in turn explain the reasoning behind the traditional "God bless you" response to a sneeze, the origins of which are currently unclear. (see "Traditional Responses To A Sneeze" below for alternative explanations). Sir Raymond Henry Payne Crawfurd, for instance, the late registrar of the Royal College of Physicians, in his 1909 book "The Last Days of Charles II", states that, when the controversial monarch was on his deathbed, his medical attendants administered a concoction of cowslips and extract of ammonia to promote sneezing. However, it is not known if this promotion of sneezing was done to hasten his death (as coup de grace), or as an ultimate attempt at treatment.

In certain parts of Eastern Asia, particularly in Chinese culture, Japanese culture and Vietnamese culture, a sneeze without an obvious cause was generally perceived as a sign that someone was talking about the sneezer at that very moment. This can be seen in the Book of Songs (a collection of Chinese poems) in ancient China as early as 1000 BC, and this belief is still depicted in present-day manga and anime. In China, Vietnam and Japan, for instance, there is a superstition that if talking behind someone's back causes the person being talked about to sneeze; as such, the sneezer can tell if something good is being said (one sneeze), something bad is being said (two sneezes in a row), even if someone is in love with them (three sneezes in a row) or if this is a sign that they are about to catch a cold (multiple sneezes).

Parallel beliefs are known to exist around the world, particularly in contemporary Greek, Celtic, English, French, and Indian cultures. Similarly, in Nepal, sneezers are believed to be remembered by someone at that particular moment.

In Indian culture, especially in northern parts of India, it has been a common superstition that a sneeze taking place before the start of any work was a sign of impending bad interruption. It was thus customary to pause in order to drink water or break any work rhythm before resuming the job at hand in order to prevent any misfortune from occurring.

In Pakistani Culture, there is a common superstition, that sneezing occurs when someone thinks fondly of them, mainly a wife.

The practice among Islamic culture, in turn, has largely been based on various Prophetic traditions and the teachings of Muhammad. An example of this is Al-Bukhaari's narrations from Abu Hurayrah that the Islamic prophet once said:

When one of you sneezes, let him say, "Al-hamdu-Lillah" (Praise be to Allah), and let his brother or companion say to him, "Yarhamuk Allah" (May Allah have mercy on you). If he says, "Yarhamuk-Allah", then let [the sneezer] say, "Yahdeekum Allah wa yuslihu baalakum" (May Allah guide you and rectify your condition).

Traditional responses to a sneeze

Main article: Responses to sneezing

In English-speaking countries, the common verbal response to another person's sneeze is "Bless You" or the less common "Gesundheit" (the German word for "good health"). There are several proposed origins for the use "Bless you" in the context of sneezing:

• Various alleged but conflicting superstitions relating the sneeze to evil spirits. This includes beliefs that a sneeze could release one's soul, thus leading to its possible capture by lurking evil spirits (as explained in the "Historic instances and practices" section above), or that the evil spirits could enter the body though the open mouth of a sneezing individual, or that the individual is sneezing out sins or evil spirits which had taken residence within the body and is thus in need of the blessing to prevent the exorcised spirits from re-entering the body. Some proponents of this last theory have further suggested that it was bad luck to open the mouth again to thank the person who uttered "Bless you" for fear of circumventing the original purpose of the blessing.
• Some say it came into use during the plague pandemics of the 14th century. Blessing the individual after showing such a symptom was thought to prevent possible impending death due to the lethal disease.
• In Renaissance times a superstition was formed claiming one's heart stopped for a very brief moment during the sneeze, saying bless you was a sign of prayer that the heart wouldn't fail possibly the devil's doing by sending demons to clasp the heart in the body's moment of shock from the sneeze.
• In Islamic culture the person who sneezes should say "al ham dulillah" which means "Praise to God" or "All praise is due to Allah."
• In the Seinfeld episode "The Good Samaritan", Jerry proposes that one should say "You're so good looking!" in response to a sneeze in lieu of "God Bless You."

Common English onomatopoeias for the sneeze sound are achoo, atchoo, achew, and atishoo, with the first syllable corresponding to the sudden intake of air, and the last to the sound of the sneeze.

See also

• Autosomal Dominant Compelling Helioophthalmic Outburst Syndrome (ACHOO)
• Photic sneeze reflex
• Snatiation

References

• Ancient Sneezing: A Gift from the Gods - Elaine Fantham, Professor of Classics at Princeton on NPR Radio.
• Why do my eyes close every time I sneeze? M.G., Sherborn The Boston Globe

Further reading

• Cecil Adams (1987). "If you hold your eyelids open while sneezing, will your eyes pop out?". The Straight Dope.
• Barbara Mikkelson (2001). "Bless You!" Urban Legends Reference Pages.
• Tom Wilson, M.D. (1997) "Why do we sneeze when we look at the sun?" MadSci Network.

External links

• The Origins of Popular Superstitions and Customs - T. Sharper Knowlson (1910), a book that listed many superstitions and customs that are still common today.
• Cold and flu advice (NHS Direct)
• Galaga effect

ar:عطس zh:噴嚏