During normal sleep, resting muscle tone acts against gravity and inspiratory pressure drop to keep the airway open. However, a relative muscular hypotonia is present in the upper airways in comparison to the awake state. During maximal airflow, the muscle tone increases and keeps the airway open. If the resting muscle tone is too low, the base of the tongue can fall against the soft pallate and throat muscle tissues relax, which can lead to partial collapse of the upper airway. This leads to increased inspiratory negative pressure, further exacerbating the collapse. Mucous membrane congestion (e.g. stuffy nose), a deviated nose septum, micrognathia (small lower jaw), polyps and enlarged adenoids (tonsils) are also contributing factors to this collapse.

For some people, this narrowing causes air to push forcefully through the throat, disturbing the relaxed muscle tissues in the back of the throat, causing them to vibrate. Instead of air flowing smoothly down the airway into the lungs, it flows with gusts and bursts. As the air travels through the airway, it picks up speed and gets whipped around in all different directions. The vibrating tissue produces the sound familiarly known as snoring.

Snoring may involve the soft palate, uvula, tonsils, tonsillar pillars, tongue, pharyngeal muscles and pharyngeal membranes, either alone or in combination.

Studies have shown a clear link between obesity and snoring. Obese people tend to have a larger tongue, a larger soft palate and additional fat deposits in the throat area. Alcohol intake (which induces muscle relaxation) and the prolonged use of sedative medication to aid sleep may actually worsen the symptoms by relaxing the oropharynx. Smoking causes irritation of mucosal structures, resulting in mucosal edema of the nose and the pharynx and causing the narrowing of the airway passages. Finally, snoring is usually most frequent and severe when sleeping on the back rather than on the side. Also, many people benefit from sleeping at a 30 degree elevation of the upper body or higher, as if in a recliner (it helps prevent the gravitational collapse of the airway).

Obstructive Sleep Apnea (OSA)

In some cases, common snoring can degenerate into obstructive sleep apnea (see section Obstructive Sleep Apnea). It is characterized by repetitive pauses in breathing during sleep (sometimes over 50 times during a night), despite the effort to breathe, and is usually associated with a reduction in blood oxygen saturation. These pauses in breathing, called apneas (literally, “without breath”), typically last 20 to 40 seconds. The patient arouses just enough to get a deep breath of air and falls right back to sleep. The individual with OSA is rarely aware of having difficulty breathing, even upon awakening. It is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body (like severe exhaustion after sleep).

Without treatment, the sleep deprivation and lack of oxygen caused by sleep apnea increases health risks such as cardiovascular disease, high blood pressure, stroke, diabetes, clinical depression, weight gain and obesity.

Watch this video on how snoring and OSA occur:

Medical Intervention

Initial primary care management consists of modifying the modifiable: giving advice on weight loss, stopping alcohol 1-2 hours before going to bed, eliminating unnecessary sedatives, and smoking cessation. Sleep posture may also be adjusted by a bolster.

Other interventions may also be employed, such as nasal decongestion with intranasal steroids or antihistamines. Long term use of nasal vasoconstrictors should be avoided due to the risk of rebound nasal congestion (rhinitis medicamentosa).

Mandibular repositioning devices are worth trying, either the simple ‘boil and bite’ designs as an initial trial, or the more effective and comfortable dentally fitted devices.

Mandibular repositioning devices advance the lower jaw about 5-6 mm, thus increasing space in the upper airway and also increasing muscle tone. They have a significant effect on snoring but are difficult for the patient to get used to. Most patients develop problems with jaw discomfort, drooling and the device becoming dislodged overnight. On the other hand, about 50% of patients enjoy a significant reduction in the intensity and frequency of snoring.

The best mechanical device for eliminating upper airway collapse is nasal continuous positive airway pressure (CPAP) or its variations VPAP and APAP. It is basically an air compressor that to a mask that is placed and secured over the patient’s nose. The device uses positive air pressure to maintain an open airway.

Patient comfort may be an issue. Some patients cannot tolerate sleeping with a mask attached to their face all night, while others complain about the noise from the compressor and that their eyes get dry from the escaping air.

Surgical interventions include nasal polypectomy, septoplasty, trimming of the turbinates, uvulopalatopharyngoplasty (UPPP), laser-assisted UPPP and bariatric surgery (weight loss surgery, e. g. gastric bypass). The patient must clearly understand the risks and benefits of any treatment. See also the page on surgery.

Reference: General Practice Update; Apr2009, Vol. 2 Issue 4, p36-42

Tips for when the person next to you snores too loudly:

 

1. Roll the person onto his or her side
2. Muffle the sound with earplugs
3. Listen to music or turn a fan on to mask the snoring noise
4. Use a nonprescription antihistamine to help you sleep
5. Sleep in a separate room
6. Ask your partner to seek a sleep doctor

Fun fact:

Explanation: The main peak each year is due to the increase in number of respiratory disease cases (common cold, flu etc.) in winter, which makes breathing and thus snoring worse. The smaller peak to the right corresponds to the peak of the allergy season in April each year (also see this plot).