If you’ve been to a concert or play recently, you know ’tis the season for coughing and sneezing–usually during the quietest moments.
Both coughing and sneezing are reflex actions (sneezing more so than coughing–you can cough deliberately, but it’s almost impossible to fake a sneeze.) And as the proud father of a five-and-a-half-month-old baby girl, I can tell you we know how to cough and sneeze from infancy–in fact, Alice sneezed as I typed this sentence.
Both sneezing and coughing are intended to expel unwanted material from the airway. Sneezes begin with an irritation in your nose. This excites the trigeminal nerve, which sends impulses to the “sneezing center,” a set of neurons in the brainstem (the most primitive part of the brain). The sneezing center responds with impulses along the facial nerve back to the nasal passages telling them to secrete fluid to wash away the irritation.
Other impulses are sent to your respiratory muscles via the spinal cord, causing you to take a quick, deep breath, then expel it with great force (at about 150 kilometres per hour!). The abdominal, chest, vocal cord and throat muscles are all involved, as is the diaphragm. So are your eyelid muscles–you always close your eyes when you sneeze.
Besides the obvious–colds, allergies, irritants like pepper, even cold air–bright light causing sneezing in about a third of the population. “Photic sneezers” inherit the trait, but nobody knows why it developed in the first place, since it has no obvious benefit. It seems to be a matter of cross-connections, so that signals from the eyes that normally result in the brain contracting the pupils get sent to the sneeze center, too.
Coughing also expels substances from the airway, in this case the throat rather than the nose. A “productive” cough is one that is obviously doing its job, because it brings up mucus or other unwanted stuff. However, a cough can also be caused by a minor irritation of the throat lining, sometimes due to nothing more than dry winter air. Since such a cough doesn’t bring up anything at all, it’s called a dry cough, and it can actually make things worse by irritating the throat even further.
A productive cough shouldn’t necessarily be suppressed, because it’s helping to keep the airway unobstructed, but dry coughs are often the target of cough drops and syrups. Cough drops reduce irritation in two ways: first, they stimulate the flow of saliva; second, they usually contain mild pain-relieving substances such as benzocaine or dyclonine hydrochloride.
Cough syrups also coat and soothe and the irritated tissue in the throat. (One of the most famous, Buckley’s, is a Canadian invention; it was created in a Toronto drug store by pharmacist William Knapp Buckley in 1919. It includes a variety of herbal ingredients that, it’s generally agreed, taste absolutely awful–but, as the company’s ad slogan says, “it works.”)
For more serious coughs, cough syrups containing the drugs dextromethorphan and codeine can provide relief. These not only reduce throat irritation but directly affect the cough control center in the brain, so you cough less frequently and less severely. However, they can also cause drowsiness.
Of course, the best way to deal with a cough is to remove its cause–get over your cold, shake off the flu, humidify the air in your home, quit smoking. Or, in some cases, reduce stress; coughing can be a nervous habit unrelated to anything going on in the respiratory passages. (Oddly, while some people deal with stress by coughing, their coughing actually causes stress in other people!)
Finally, have you ever wondered why people say “God bless you,” or “Gesundheit” (which means the same thing) when other people sneeze? It’s common to many different cultures around the world, and references to invoking a divine blessing on someone who sneezes date back to the first century A.D.
It’s probably because early people closely connected the breath with the soul. They worried that when you sneezed, such a forceful expulsion of breath could literally sneeze out your soul, resulting in your death.
Today, of course, we know that you’re not sneezing out your soul, but you are sneezing out millions of viruses and bacteria. So please, cover your mouth. And then wash the hand you used to cover your mouth before you shake my hand or touch a door handle or anything else I might be touching myself soon.
Interesting as it is to write about sneezing and coughing, I’d rather avoid the first-hand experience.