To describe snoring exactly is not so easy. The general term “snoring” is neither a medical, nor scientific term, but rather an everyday collective term for all rattling and grunting noises associated with breathing, that occur during sleep. The question “why do people snore” only is only of medical interest when what is often, very loud snoring, is a side effect of other illnesses, or a so-called sleep related breathing disorder. However, we want to explain to all those that affected what by this annoying phenomenon what the causes of snoring are and why these often very loud snoring noises occur.

Just heavy breathing or actual snoring?

Every child knows how snoring sounds from an early age. When children pretend they’re sleeping, they are quick to imitate very loud snoring sounds.

What is completely clear to a child’s untrained ear, however, is no longer so clear in the field of medicine. The main question that has not yet been clarified is: “What is the difference between heavy breathing and snoring during sleep?”. Many of us are familiar with the problem, especially when we have a cold. Nasal congestion results in loud, heavy breathing. Sometimes our breathing whistles easily, rattles, or even bubbles, when we are suffering from a cold. But is this actually classified as snoring? The correct answer is: maybe! In any case, medicine does not give a clear answer, as long as the snoring is not pathological. Therefore there are still no guidelines, which for example would classify snoring based upon a particular noise level (dB).

The German Society for Sleep Research and Sleep Medicine (Die Deutsche Gesellschaft für Schlafforschung und Schlafmedizin, the DGSM) has, however, included at least one “negative definition” for simple snoring in its ICD-10 guidelines. Put simply, snoring is everything that remains after filtering out a possible sleep related breathing disorder.

Primary snoring

Primary or habitual snoring is defined by breathing noises occurring during sleep, which exist almost every night, but which do not cause any disturbance of the circulation regulation or the arterial oxygen content and are accompanied by an increase in the number of arousal reactions (from sleep) in the EEG (ICD-10: R06.5).

Pathological snoring or purely very loud snoring?

In any case, medicine does not primarily focus on the intensity of snoring sounds, but on the causes of snoring. If the very loud snoring noises are the result of a sleep related breathing disorder, then doctors start taking interest! They look at what the underlying causes of the snoring noise and whether the underlying cause is pathological in nature. These special forms of pathological snoring are medically defined.

Sleep related breathing disorder

If the snoring noise arises because the airways in the back of the throat collapse or are misaligned and the snorer consequently experiences interruption in breathing, then this is such a sleep related breathing disorder. Medicine has further defined this particular form of snoring as obstructive sleep apnea syndrome (OSAS), which is similar to ” upper airway resistance syndrome” (UARS). These forms of pathological snoring are, however, relatively rare.

Primary snoring

In most cases, the snoring is not accompanied by a sleep related breathing disorder. Medicine does not define this non pathological area of snoring in more detail, but generally refers to it as “primary snoring” or “habitual snoring”. To put it simply: primary snoring is any vibration noise in the upper respiratory tract that does not lead to respiratory disturbance during sleep. Or even simpler: primary snoring is all that remains if you subtract the “bad” forms of snoring.

This “simple” form affects the majority of snorers, but is not as trivial as it may sound. After all, snoring always means disturbed breathing and sleeping behaviour. In addition, it can be accompanied by symptoms such as dry mouth and dry mouth can even result in damage to the teeth. There is even the suspicion (which has not been scientifically substantiated to date) that intense, primary snoring could be a risk factor for stroke.

Primary snoring in known by many different terms, sometimes it is called primary snoring, sometimes habitual snoring; but terms like benign snoring, continuous snoring, rhythmic snoring, non-apnoeic snoring or even harmless snoring are also used to describe it.

General causes of snoring

But why do people snore? What exactly happens inside the body, when we snore? Unfortunately, there is no one-size-fits-all explanation for this, because noise in the respiratory tract can develop at different points in the mouth, nose or throat. That is why there is not just one cause for snoring, nor only one type of snoring.

However, all types of snoring can ultimately be traced back to two major snoring causes: tissue weakness and the formation of negative pressure in the respiratory tract.

Flaccid tissue in the respiratory tract

Untoned muscles are not just an annoying problem associated with the abdomen, legs and buttock area, but also the mouth and throat! If the tissue in and around the respiratory tract lacks firmness and tone, snoring is promoted. People with general tissue weakness usually snore more often.

When the person is awake, the entire throat area is under muscular tension and wide open. During sleep, however, the tissue relaxes and slackens. It is even possible that the throat area collapses completely during the deep sleep phase. In this case, the pharyngeal walls fold in on top of each other.

Snoring due to vibration

The air which flows through the nose into the throat, sets the flabby tissue in motion and it begins to vibrate . This vibration results in annoying snoring noises. What happens is similar to the effect of a billowing curtain in front of an open window.

Creation of negative pressure in the respiratory tract

With each inhalation, the lungs generate a slight negative pressure in the respiratory tract. This is completely natural and necessary for breathing. This negative pressure causes the airways to contract slightly with each inhalation.

If the tissue in the mouth and throat is relaxed, i.e. slack, as it is whilst we sleep, it causes narrowing of the airways due to the negative atmospheric. Air turbulence, and thus vibrations, occur at the narrowed points. These vibrations become audible, often as very loud snoring noises.

The negative atmospheric pressure in the respiratory tract can be further intensified by narrowing of the nasal passage; this narrowing can be caused by polyps, enlarged nasal conchae or by a deviated septum. Free nasal breathing is therefore an important prerequisite for a peaceful night’s sleep, free from snoring.

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Dr. Jan Wrede

Medical Doctor, Berlin

Jan Wrede works as a medical doctor in Berlin. He studied medicine at FAU University in Erlangen-Nuremberg and Semmelweis University in Budapest. He had already written numerous scientific articles during his studies, especially on the subject of snoring.