Snoring is a raspy noise produced in the nasopharynx during sleep. It is quite common, occurring in about 57% of men and 40% of women; prevalence increases with age. However, because a bed partner's perception of and response to snoring is highly subjective and because snoring varies from night to night, prevalence estimates vary widely.
The sound ranges from barely audible to an extremely bothersome noise that may be loud enough to hear in another room. Snoring is distressing usually to others (typically a bed partner or roommate trying to sleep) rather than the snorer; uncommonly, snorers wake up to the sound of their own snoring.
Snoring can have significant social consequences. It can cause strife between bed partners or roommates.
Other symptoms such as frequent awakenings, gasping or choking during sleep, excessive daytime sleepiness, and morning headaches may also be present, depending on the severity, cause, and consequences of the snoring.
Pathophysiology of Snoring
Snoring results from airflow-induced flutter of soft tissues of the nasopharynx, particularly the soft palate. As in any fluttering physical structure (eg, a flag), flutter in the nasopharynx develops depending on interacting factors, including the mass, stiffness, and attachments of the fluttering element and the velocity and direction of airflow.
The fact that people do not snore while awake suggests that sleep-induced muscular relaxation is at least part of the etiology because muscle tone is the only component of flutter that can change during sleep; tissue mass and attachments do not change. Furthermore, if pharyngeal dilators cannot keep the airway open in response to the negative intraluminal pressure induced by inspiration, the upper airway narrows, increasing local airflow velocity (for a given inspiratory volume). The increased flow velocity promotes flutter directly and decreases intraluminal pressure, further enhancing airway closure and thus promoting flutter and snoring.
Snoring is more likely to occur in airways that are already compromised by structural factors, including
Micrognathia or retrognathia
Nasal septal deviation
Rhinitis that causes tissue swelling
Enlarged soft palate
Enlarged lateral pharyngeal walls
Etiology of Snoring
Primary snoring is snoring that is not accompanied by awakening or excessive arousals, limitation of airflow, oxygen desaturation, or arrhythmias during sleep and that occurs in people who do not have excessive daytime sleepiness. Arousals are brief transitions to lighter sleep or awakenings that last < 15 seconds and are usually not noticed.
Snoring is usually a symptom of sleep-disordered breathing, which covers a spectrum ranging from upper airway resistance syndrome to obstructive sleep apnea Obstructive Sleep Apnea (OSA) Obstructive sleep apnea (OSA) consists of multiple episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of... read more (OSA). Each has similar upper airway obstructive pathophysiology but differs in degree and clinical consequences of the airway obstruction. The clinical consequences involve mainly disturbances of sleep and/or airflow.
Patients with obstructive sleep apnea have ≥ 5 episodes of apnea or hypopnea (with each episode lasting at least 10 seconds) per hour during sleep (apnea/hypopnea index [AHI]) plus ≥ 1 of the following:
Daytime sleepiness, unintentional sleep episodes, unrefreshing sleep, fatigue, or insomnia
Awakening with breath holding, gasping, or choking
Reports by a bed partner of loud snoring, breathing interruptions, or both during the patient's sleep
Obstructive sleep apnea can be categorized by severity:
Mild: 5 to 15 episodes/hour
Moderate: 16 to 30 episodes/hour
Severe: > 30 episodes/hour
Upper airway resistance syndrome (airflow limitation secondary to increased upper airway resistance or respiratory effort–related arousals [RERAs]) can cause excessive daytime sleepiness or other manifestations suggesting obstructive sleep apnea but with few episodes of apnea/hypopnea or oxygen desaturation and thus does not meet full criteria for obstructive sleep apnea.
Although snoring itself has no known adverse physiologic effects, obstructive sleep apnea may have consequences (eg, hypertension, stroke, heart disorders, diabetes).
Risk factors for snoring include
Use of alcohol or other sedatives
Chronic nasal congestion or blockage
A small or posteriorly displaced jaw
Abnormal structures that can block airflow (eg, large tonsils, a deviated nasal septum, nasal polyps, macroglossia, an enlarged soft palate, lateral pharyngeal narrowing)
There may also be familial risk.
Evaluation of Snoring
The primary goal is to identify snorers who are at high risk of having obstructive sleep apnea. Many snorers do not have OSA, but most patients with OSA snore (the precise proportion is not known).
Because several important manifestations of OSA are noticed mainly by others, bed partners or roommates should also be interviewed when possible.
History of present illness should cover severity of snoring, including its frequency, duration, and loudness. Also, the degree that snoring affects the bed partner should be noted.
Review of systems should seek symptoms suggesting obstructive sleep apnea, such as the presence of sleep disturbance as indicated by
Number of awakenings
Witnessed apneic or gasping/choking episodes
Presence of unrefreshing sleep or morning headaches
Excessive daytime sleepiness
The Epworth Sleepiness Scale can be used to quantify daytime sleepiness. The STOP-BANG score (see table STOP-BANG Risk Score for Obstructive Sleep Apnea STOP-BANG Risk Score for Obstructive Sleep Apnea ) is a useful tool to predict risk of OSA for patients who snore.
Past medical history should note presence of disorders that may be associated with OSA, particularly hypertension Hypertension Hypertension is sustained elevation of resting systolic blood pressure (≥ 130 mm Hg), diastolic blood pressure (≥ 80 mm Hg), or both. Hypertension with no known cause (primary; formerly, essential... read more , coronary ischemia, heart failure Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more , stroke Overview of Stroke Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be Ischemic (80%), typically resulting... read more , gastroesophageal reflux disease Gastroesophageal Reflux Disease (GERD) Incompetence of the lower esophageal sphincter allows reflux of gastric contents into the esophagus, causing burning pain. Prolonged reflux may lead to esophagitis, stricture, and rarely metaplasia... read more (GERD), atrial fibrillation Atrial Fibrillation Atrial fibrillation is a rapid, irregularly irregular atrial rhythm. Symptoms include palpitations and sometimes weakness, effort intolerance, dyspnea, and presyncope. Atrial thrombi may form... read more , depression Depressive Disorders Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more , obesity Obesity Obesity is excess body weight, defined as a body mass index (BMI) of ≥ 30 kg/m2. Complications include cardiovascular disorders (particularly in people with excess abdominal fat)... read more (especially morbid obesity), and diabetes Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more . Patients are asked how much alcohol they consume and when it is consumed in relation to bedtime. Drug history may identify sedating or muscle-relaxing drugs.
Examination should begin by measuring height and weight, with calculation of body mass index (BMI).
The rest of the examination should focus on inspecting the nose and mouth for evidence of obstruction. Signs include
Nasal polyps and engorged turbinates
A high, narrow arched palate
Enlargement of the tongue, tonsils, soft palate, lateral pharyngeal walls, or uvula
A small or posteriorly displaced mandible (retrognathia)
A modified Mallampati score of 3 or 4 (only the base or none of the uvula is visible during oral inspection—see figure Mallampati scoring Modified Mallampati scoring ) suggests increased risk of OSA.
Modified Mallampati scoring
Modified Mallampati scoring is as follows:
The following findings are of particular concern:
Witnessed apnea or choking during sleep
Epworth sleepiness score ≥ 10
BMI ≥ 35 kg/m2
Very loud, constant snoring
Interpretation of findings
The clinical evaluation is not completely reliable for diagnosis of obstructive sleep apnea but can be suggestive. Red flag findings clearly correlate with OSA. However, all of these findings occur along a continuum, and there is no widespread agreement on cut-off points and relative weighting. Nonetheless, the more red flag findings a patient has and the more severe they are, the greater the likelihood of OSA.
Testing is done when a diagnosis of obstructive sleep apnea is suspected; it consists of polysomnography Testing (in a laboratory or at home). Polysomnography should be done when clinical suspicion for OSA is significant. Patients who should be tested include those who have red flag findings (particularly witnessed apnea), including those whose test scores (eg, STOP-BANG risk score for OSA) are not quite high enough for a diagnosis of OSA. However, because snoring is so common, polysomnography, particularly home testing, which is not as expensive, can be used more liberally and should be considered when clinical suspicion for OSA is lower.
People with no symptoms or signs of sleep disturbance other than snoring may not need to be tested but should be clinically monitored for development of such manifestations.
Treatment of Snoring
Treatment of snoring associated with other conditions, such as chronic nasal obstruction Treatment Nasal congestion and rhinorrhea (runny nose) are extremely common problems that commonly occur together but occasionally occur alone. The most common causes (see table ) are Upper respiratory... read more and obstructive sleep apnea Treatment Obstructive sleep apnea (OSA) consists of multiple episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of... read more , are discussed elsewhere in THE MANUAL.
Overall, treatment includes general measures to manage risk factors plus physical methods to open the airways and/or stiffen the involved structures.
Several general measures can be used for primary snoring. Their efficacy has not been well-evaluated, primarily because perception of snoring is highly subjective; However, particular patients may benefit. Measures include
Avoiding alcohol and sedating drugs for several hours before bedtime
Sleeping with the head elevated (best accomplished by using bed- or body-positioning devices such as wedges) or sleeping in the lateral decubitus position
Treating any nasal congestion (eg, with decongestant and/or corticosteroid sprays)
Bed partners may benefit from using earplugs or white-noise machines. Sometimes alternate sleeping arrangements (eg, separate rooms) are necessary.
Oral appliances are worn only during sleep; they include
Mandibular advancement devices
These appliances should be fitted by specially trained dentists. They are helpful for patients with OSA and are generally regarded as effective for simple snoring, although studies in this area are scant.
Adverse effects include temporomandibular joint (TMJ) discomfort, dental misalignment, and excessive salivation, but most patients tolerate the devices well.
Mandibular advancement devices are most commonly used. These devices move the mandible and tongue forward relative to the maxilla and thus increase airway caliber during sleep. These devices can be adjusted incrementally after the initial fitting to optimize results.
Tongue-retaining devices use suction to maintain the tongue in an anterior position. Tongue-retaining devices are more uncomfortable than mandibular advancement devices.
A recently developed, removable tongue muscle stimulator is designed to be used during the day and to improve tongue muscle function in patients with snoring or OSA. However, more data are needed to confirm effectiveness.
Continuous positive airway pressure (CPAP)
CPAP devices Treatment Obstructive sleep apnea (OSA) consists of multiple episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of... read more maintain a constant positive pressure in the upper airway via a small mask applied to the nose or nose and mouth. By increasing the caliber of the upper airway, CPAP prevents narrowing or collapse of the upper airway during sleep. It thus is very effective for OSA and is effective for primary snoring. However, patients may have difficulty tolerating CPAP, and its use in primary snoring is limited because third-party reimbursement for this use is lacking. Although patients are often willing to use a CPAP device nightly to avoid the significant symptoms and long-term consequences of OSA, they are less willing to use the device to manage primary snoring, whose consequences are primarily social.
Because reduced nasal patency promotes snoring, surgically correcting specific causes of airway compromise (eg, nasal polyps, hypertrophied tonsils, deviated septum) may be a reasonable way to decrease snoring. However, studies have not yet substantiated this theory.
Various pharyngeal surgical procedures that alter the structure of the palate and sometimes the uvula have been developed for obstructive sleep apnea. Some are also useful for nonapneic snoring.
Uvulopalatopharyngoplasty involves remodeling the uvula, palate, and pharyngeal walls to increase the size of the airway. It can be effective for snoring, although effects may not last beyond a few years. It is an inpatient procedure requiring general anesthesia; thus, its usefulness for snoring alone is limited.
Therefore, a number of outpatient palate-altering procedures requiring only a local anesthetic have been developed:
Laser-assisted uvuloplasty is less invasive than uvulopalatopharyngoplasty. Although some patients report benefit, its usefulness in treating snoring has not been proved.
For injection snoreplasty, a sclerotherapeutic agent is injected into the submucosa of the soft palate to stiffen it and the uvula. Its usefulness for snoring alone requires further study.
For radiofrequency ablation, a probe is used to introduce thermal energy into the soft palate. Studies have shown its usefulness for snoring, but further study is needed.
Palatal implants, made of polyethylene, can be placed into the soft palate to stiffen it. Three small implants are used. Their usefulness for snoring alone has not been proved, and the implants can extrude.
Only some snorers have obstructive sleep apnea (OSA), but most patients who have OSA snore.
Clinical risk factors such as nocturnal apneic or choking episodes, daytime sleepiness, and a high BMI help identify patients at risk of OSA and thus in need of testing with polysomnography or home sleep studies.
Recommend general measures to reduce snoring (eg, avoiding alcohol and sedating drugs, sleeping with the head elevated or in the lateral decubitus position, losing weight).
Consider specific measures such as mandibular advancement devices, uvulopalatopharyngoplasty, palate-altering procedures, and CPAP to treat snoring due to OSA.