The physics behind a snore

 

Elsewhere, we have described the generation of stridor in a narrowed larynx. Snoring arises through the same physical laws: air flowing through a narrowing will increase in velocity and become turbulent. Remember that turbulent, non-laminar airflow becomes more likely as air velocity increases. 

 

The upper airways are soft and mobile and the turbulence cause them to vibrate. Snoring tends to occur more during inspiration because of the negative pressures generated in respiration to draw air in. This causes the narrow airway to become narrower still. Expiration raises the pressure in the airway and widens it making noise less likely (but not impossible). Continuous positive airway pressure does the same thing – see treatment of OSAS below.

 

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Who snores?

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When Charles Dickens created the retired, successful Mr. Pickwick he described the classic snorer: ageing, male, and overweight. But it is Joe, "the fat boy" from the same story that has symptoms of OSAS. He ate a great deal, continually fell asleep, and snored at the dinner table. OSAS was originally called "Pickwickian syndrome" after Joe.

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Age 

Snoring becomes more common as you get older because the airways slowly lose their muscular support. This makes them floppier and more likely to vibrate.

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Sex 

Men snore more than women. This may have something to do with the differing size of the airway but is also related to female hormones; women snore more at menopause.

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Body Mass Index 

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Being overweight is a significant risk factor for snoring in both sexes. Fat deposits within the neck narrow the airway making it more prone to vibrate. Note that thin people can suffer too but for other reasons

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Social habits

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Smoking and alcohol consumption both increase the risk of snoring.

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Drugs 

Medications such as sleeping tablets and some sedating antihistamines can increase the risk of snoring.

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Upper airway disease 

Nasal disease or trauma increase the risk of snoring because a blocked nose requires a higher inspiratory effort. This means a greater negative pressure in the airway and greater collapse of soft tissues.

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Upper airway anatomy

Even thin people can snore if their anatomy causes narrowing of the upper airway. Children have naturally large tonsils and adenoids causing anything from snoring to full blown OSAS. Enlarged lingual tonsils, retrognathia, long epiglottides or uvulae can all cause vibration in the airway.

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What can be done about snoring?

 

Since the more easily modified risks are weight, smoking, alcohol consumption, sedatives, and nasal disease, it is not surprising that, for the majority of sufferers, these will be the first things that the doctor will discuss. 

 

Weight reduction in the overweight or obese patient will usually ease the symptom of snoring and it will have tremendous impact on their other health too. Stopping smoking will also have a beneficial effect beyond the snoring problem.

 

Reduction in alcohol consumption will be needed to lose weight, especially in those people that drink to excess. 

 

General Practitioners will manage any mucosal disease in the nose with nasal douching with or without nasal steroids. They will review medications to seek non-sedating alternatives.

 

Should these steps fail or not be appropriate then a referral for consideration of surgery will be considered. Surgery for snoring is rarely required if the patient is able to modify their lifestyle, lose weight or change the medications that may predispose them to snoring. However, some patients will come to surgery anyway.

 

The ENT Department will organise a sleep study and, if there is no suggestion of UARS/OSAS, may consider surgery targeted at the narrowing in the airway. This might mean a nasal operation or surgery to the oropharynx to reduce the soft palate and uvula, and remove the tonsils. Occasionally, surgery to reduce the lingual tonsil is also needed.

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One such operation is shown below. In this procedure the patient has been found to have snoring caused by vibrations in the palate and lateral oropharyngeal wall. The tonsils and the free edge of the soft palate have been removed.

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