sneeze

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A sneeze (or sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, 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. Sneezing may spread disease like H1N1.

Sneezing can help spread disease.

Biological elements

The function of sneezing is to expel foreign particles or irritants and cleanse the nasal cavity, particularly during viral infections. 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

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 the 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.

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.^[1]

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.^[2]

Conservative estimates place the speed of release at 75 kilometers per hour (47 mph) or 28 meters per second (92 ft/s). The highest estimates — such as by the Health World Museum in Barrington, Illinois — propose speeds as fast as 85% of the speed of sound, corresponding to 1,045 kilometers per hour (649 mph) or 290 meters per second (950 ft/s).^{[citation needed]}

Preventative measures

Examples of preventative 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, and crinkling the nose. Clinical evidence suggests the sneeze reflex is inhibited by applying strong pressure immediately below the nose, using the index finger.^{[citation needed]}

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.^[3]

Cultural elements

Onomatopoeia

Some 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 second to the sound of the sneeze.

Italian has "Etciu!" or "Ecciu!"

Spanish has "Achis!" or "Achus!"

Historic instances and practices

In the 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^{[citation needed]} 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.^[4] 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 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 - a belief that 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), 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.

The practice among certain Islamic cultures, 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

It has been suggested that this section be split into a new article titled Responses to sneezing. (Discuss)

In English-speaking countries, the common verbal response to another person's sneeze is "(God) Bless You" or the less common "Gesundheit" (the German word for "healthiness"). 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.^{[citation needed]}
• Some say it came into use during the plague pandemics of the fourteenth 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.
• A polite way of congratulating the sneezer for his or her impending good luck as signaled by the sneeze.

In non-English-speaking cultures, words referencing good health or a long life are used instead of "Bless you":

See also

Wikimedia Commons has media related to: Sneeze

• Photic sneeze reflex
• Snatiation

Notes

1. ^ "A Moment of Science: Sleep On, Sneeze Not". http://amos.indiana.edu/library/scripts/sleepsneeze.html. Retrieved 2008-11-14. 
2. ^ Cole EC, Cook CE. Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies. Am J Infect Control. 1998 Aug;26(4):453-64. Sneezing can transmit many diseases PMID 9721404
3. ^ Adkinson NF Jr. (2003). "Middleton’s Allergy: Principles and Practice.". Phytomedicine.. 
4. ^ Wylie, A, (1927). "Rhinology and laryngology in literature and Folk-Lore". The Journal of Laryngology & Otology 42 (2): 81–87. 
5. ^ Visindavefur.is (Icelandic): http://visindavefur.is/svar.php?id=6044

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

Look up sneeze in Wiktionary, the free dictionary.

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