Snoring is caused when the soft tissue in your head and neck vibrates as you breathe in and out. Tissue that can be affected includes:
- nasal passages
- soft palate – a soft layer of tissue in the roof of your mouth
- base of your tongue
- tonsils – the two small glands that sit above the tongue at the junction of the mouth and pharynx (the pharynx is the upper section of the throat)
- uvula – a small cone-shaped section of tissue that hangs between your tonsils
Bernoulli principle
While you are asleep, the various airways in your neck and head will narrow. It is thought that the narrowing of the airways triggers an effect that is known as the Bernoulli principle.
The Bernoulli principle, which is named after the Dutch mathematician who first described it, helps to explain how the flow of a fluid or gas through a passageway will speed up if the passageway is narrowed.
The narrowing of your airways during sleep means that the speed at which you are breathing out increases. The increase in the speed of your breathing leads to a corresponding decrease in air pressure. It is the decrease in air pressure that causes the soft tissue to vibrate by sucking the sides of the airways in.
There is evidence to suggest that if snoring is left untreated it will get worse over time. The vibrations that occur during snoring appear to damage the blood vessels that supply the muscles in the head and neck. This may, over many years, cause the muscles to weaken.
If the muscles in your head and neck become weakened, their ability to keep your airways open will be affected, making you more likely to snore frequently and loudly.
Risk factors
Known risk factors for habitual snoring include:
- being obese – particularly if you have a large amount of fat around your neck. People with a neck circumference (the distance around the neck) of more than 43cm (17 inches) usually snore a lot.
- drinking alcohol – alcohol relaxes your muscles when you sleep, which increases the narrowing of your airways
- sedatives and some types of antidepressants – in some people, these medications can have a similar effect on the muscles as alcohol
- smoking – tobacco smoke can cause your airways to become inflamed, which increases the narrowing of the airways when you smoke
- allergic rhinitis – this is a condition where the inside of your nose becomes swollen and inflamed due to an allergic reaction to substances such as dust or pollen
