Snoring – Cause and possible implications

Snoring! We all have it … but we all deny it … until we are recorded on tape. So what is snoring and what causes this music of the night. 

Snoring in itself is harmless to the person who produces it. It can and does create domestic problems whereby it disturbs the sleep of the partner, and many marriages can be strained by it. Snoring suggests that insufficient air is passing through the airway from the nose to the windpipe. Now this may sound like obstructive sleep apnea syndrome (OSAS) which is a condition that is linked to heart disease, strokes and high blood pressure but (noisy) snoring and (life-changing) OSAS are two very different conditions. How are their linked? Simply put, not every snorer has OSAS but anyone with OSAS will snore. Hence as a sign, snoring should alert someone to the possibility that they may have an underlying obstructive sleep problem, blocked nose, large tonsils, etc. that require medical attention. 

What causes snoring? To understand this, let’s look at the physics of sound production. If we pass air through a small tube fast enough, we create a sound either by the vibration of the turbulent air molecules e.g. by whistling, or when our soft tissue vibrates against another structure e.g. snoring. This explains why not every snorer has OSAS. With OSAS, during the sleep cycle, airflow is reduced until finally no air can pass through, and hence no (snoring) sound is produced. This second part explains why all OSAS patients with upper airway obstruction, will snore. 

In snoring, we are unable to maintain an adequately open upper airway passage (e.g. from blocked nose or large tonsils). Hence our soft tissues are drawn together by the lowered air pressure in our throat when we try to breath. But almost as suddenly as it happens, the soft tissue is pulled back again by its soft tissue attachment that resists this collapsing effort. This vibrating cycle happens very fast. The result is our soft tissue will flap and clap together against one another very fast, producing (the snoring) noise. 

Snoring occurs at one or more than one level of our throat, and at the same time. If the nose is blocked, the low pressure behind our uvula and soft palate causes this to vibrate very quickly hitting the back of the throat, creating a beating sound. The same occurs when the tonsils are large and they clap together very quickly like cymbals. Further down, just as we fall into a deep sleep, all our muscles of the body relax including our tongue and /or epiglottis. The tongue can drop back, momentarily obstructing our airway, and then re-opening again; this again creates a noise like releasing the air from air-filled sausage balloon. 

All of this explains why snoring is so “melodious”. Each level creates its own sound. As each level plays its own music, snoring is like an orchestra to the usually distressed listener. It should be said that although we all laugh and joke about snoring, you can now understand that, in science terms, it suggests a partially blocked and insufficient airway during sleep with poor sleep quality for both “musician” and listener. No one is ever born to snore, and “the music of the night”, may not be such good music after all.

 

In the next article, I will discuss what can be done to investigate and exclude OSAS in snorers, and how snoring can be treated.

The Chinese version of this article was published in Hong Kong Economic Journal on 3 March, 2014