Snoring
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Snoring is an abnormal breath sound caused by partially obstructed, turbulent airflow and vibration of tissues in the upper respiratory tract (e.g.,
uvula The uvula (: uvulas or uvulae), also known as the palatine uvula or staphyle, is a conic projection from the back edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fi ...
,
soft palate The soft palate (also known as the velum, palatal velum, or muscular palate) is, in mammals, the soft biological tissue, tissue constituting the back of the roof of the mouth. The soft palate is part of the palate of the mouth; the other part is ...
, base of
tongue The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...
) which occurs during
sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...
. It usually happens during
inhalation Inhalation (or inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
s (breathing in). Primary snoring is snoring without any associated sleep disorders and usually without any serious health effects. It is usually defined as apnea–hypopnea index score or respiratory disturbance index score less than 5 events per hour (as diagnosed with
polysomnography Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς ('' ...
or home sleep apnea test) and lack of daytime sleepiness. Snoring may also be a symptom of upper airway resistance syndrome or
obstructive sleep apnea Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder and is characterized by recurrent episodes of complete or partial airway obstruction, obstruction of the respiratory tract#Upper respiratory tract, upper airway lea ...
(apneic snoring). In obstructive sleep apnea, snoring occurs in combination with breath holding, gasping, or choking.


Classification

In the International Classification of Sleep Disorders third edition (ICSD-3), snoring is listed under "Isolated symptoms and normal variants" in the section " Sleep-related breathing disorders". The manual defines snoring as "a respiratory sound generated in the upper airway during sleep that typically occurs during inspiration but may also occur in expiration." Primary snoring (also termed simple snoring, non-apneic snoring, or isolated snoring) is snoring without any other associated medical condition. Primary snoring is not associated with episodes of
sleep apnea Sleep apnea (sleep apnoea or sleep apnœa in British English) is a sleep-related breathing disorder in which repetitive Apnea, pauses in breathing, periods of shallow breathing, or collapse of the upper airway during sleep results in poor vent ...
(cessation of breathing), hypopnea, respiratory-effort related arousals, or
hypoventilation Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide ( hypercap ...
. Traditionally, primary snoring is considered as benign and having no significant health effects for the individual. However, the idea that primary snoring without sleep apnea has no negative health effects is being increasingly challenged, especially primary snoring in children. For example, there is evidence that primary snoring causes excessive daytime sleepiness, and it may be linked with several other medical problems, some of which are serious. Even so, it is generally accepted that primary snoring cannot be diagnosed in the presence of sleep apnea. Snoring is one of the main symptoms of obstructive sleep apnea, in which case it is apneic snoring. In obstructive sleep apnea, snoring occurs in combination with other features such as breath holding (breathing cessation), gasping, or choking. There are also other features like daytime sleepiness, nonrestorative sleep, fatigue, or
insomnia Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low ene ...
. Snoring has also been classified according to frequency as occasional snoring (occurring on three nights or less per week) and habitual snoring (occurring on most nights; synonymous with primary snoring). Snoring has been classified according to apnea–hypopnea index score and severity of associated sleep disorders. Therefore, snoring as a symptom exists as a spectrum of severity, with primary snoring being the least severe, snoring with upper airway resistance syndrome being of intermediate severity, and snoring associated with obstructive sleep apnea being the most medically significant. This spectrum of conditions represents increasing degrees of airway obstruction and severity and frequency of disruption of breathing during sleep. Obstructive sleep apnea may be subdivided into mild, moderate, and severe types. * Asymptomatic, non-apneic snoring (primary snoring). No daytime sleepiness and apnea–hypopnea index less than 5 per hour. * Non-apneic snoring with upper airway resistance syndrome. Daytime sleepiness present. Apnea–hypopnea index less than 5 per hour. Between 5 and 10 respiratory-effort-related arousals per hour.
Oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is Dissolution (chemistry), dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the g ...
more than 90%. * Apneic snoring (snoring associated with obstructive sleep apnea). Apnea–hypopnea index more than 5 per hour. Oxygen saturation less than 90%. Deviating pattern on electroencephalogram. Primary snoring is occasionally defined as apnea-hypopnea less than 15 (or less than 10) with
body mass index Body mass index (BMI) is a value derived from the mass (Mass versus weight, weight) and height of a person. The BMI is defined as the human body weight, body mass divided by the square (algebra), square of the human height, body height, and is ...
less than 32 kg/m2. It has been suggested that individuals with primary snoring may gradually progress towards obstructive sleep apnea as causative factors such as aging and obesity change over time. However, there is limited evidence for this. 37% of children with primary snoring progressed to obstructive sleep apnea after 4 years. On the other hand, in many cases snoring is resolved over time rather than getting worse. Snoring severity has also been classified according to average maximum volume: * Mild (40-50
decibels The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a ...
). Roughly equivalent to quiet conversation. * Moderate (50–60 dB). Roughly equivalent to a car driving past at low speed. * Severe (>60 dB). Roughly equivalent to busy traffic or a vacuum cleaner. In snoring associated with obstructive sleep apnea, louder snoring is correlated with severity of sleep apnea. On average, males snore more loudly than females, and people with higher body mass index snore louder than those with lower body mass index.


Mechanism

Snoring has been mathematically modelled wherein the upper airway is a tube which has an elastic or collapsible section. As the section of the upper airway narrows, resistance to the flow of air increases. There is a cyclical obstruction and reopening of the airway at the partially or fully collapsed section as air flows past. This obstruction and reopening occurs at approximately 50 times per second, which causes vibration and noise. The airflow becomes unstable and turbulent. The structures that obstruct the airway and vibrate are various
soft tissue Soft tissue connective tissue, connects and surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, Adipose tissue, fat, fibrous tissue, Lymphatic vessel, lymph and blood vessels, fasciae, and synovial membranes.� ...
structures at different levels along the upper respiratory tract or aerodigestive tract. These are the
uvula The uvula (: uvulas or uvulae), also known as the palatine uvula or staphyle, is a conic projection from the back edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fi ...
,
soft palate The soft palate (also known as the velum, palatal velum, or muscular palate) is, in mammals, the soft biological tissue, tissue constituting the back of the roof of the mouth. The soft palate is part of the palate of the mouth; the other part is ...
, faucial pillars ( palatoglossal arch, palatopharyngeal arch),
palatine tonsil Palatine tonsils, commonly called the tonsils and occasionally called the faucial tonsils, are tonsils located on the left and right sides at the back of the throat in humans and other mammals, which can often be seen as flesh-colored, pinkish ...
s, adenoid tonsil, walls of the
pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...
, epiglottis, or lower structures. These structures may relax during sleep and move position, especially under the influence of gravity. This results in partial obstruction (narrowing) or complete obstruction of the airway. Partial obstruction of the airway is more associated with primary snoring, whereas complete obstruction is more a feature of obstructive sleep apnea. The following structures were found to vibrate during snoring: soft palate in 100% of cases, pharynx (53.8%), lateral pharyngeal wall (42.3%), epiglottis (42.3%), and tongue base (26.9%). In primary snoring there may be vibration of the soft palate alone, termed "palatal fluttering". In mild to moderate obstructive sleep apnea, there may be vibration of the palate and lateral pharyngeal wall. In severe obstructive sleep apnea, there may be vibration of the tongue base and epiglottis in addition to the above structures. The snoring sound mainly occurs during inhalation (breathing in), but it may occur during exhalation (breathing out). Snorers have more negative pressure in their airway, increased inspiratory time, and limitation of respiratory flow. On
polysomnography Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς ('' ...
, snoring is usually louder during slow-wave sleep (stage 3 non-rapid eye movement sleep) or
rapid eye movement sleep Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals (including humans) and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the s ...
. Snoring in obstructive sleep apnea usually occurs when airflow turbulence is maximum, which is during hyperpnea episodes at the end of
apnea Apnea (also spelled apnoea in British English) is the temporary cessation of breathing. During apnea, there is no movement of the muscles of inhalation, and the volume of the lungs initially remains unchanged. Depending on how blocked the ...
events (breathing cessation).


Causes

Snoring is often considered according to the location (level) of structure that is causing the obstruction and vibration. However, the sites causing the snoring vary from one person to the next, and the same individual may have multiple different sites which are contributing to the problem.


Nasal cavity

While it is generally not possible for the rigidly supported structures inside the nose to vibrate, the patency of the nasal airway is important in the development of snoring. The
nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nas ...
causes over 50% of the total airway resistance, particularly at the internal and external nasal valves. The internal nasal valve is located approximately 1.5 cm from the nostril and constitutes the narrowest part of the upper airway. The external nasal valve is the tissue immediately around the nostril. Nasal valve collapse refers to weakening or narrowing of the supporting cartilage at the nasal valves. As per the Hagen–Poiseuille equation, a minimal reduction in the diameter of a tube (in this case the nasal airway) results in an exponential change in airflow. Nasal valve collapse is a cause of snoring. Nasal congestion (nasal obstruction) reduces sleep quality. Common reasons for nasal obstruction are
allergic rhinitis Allergic rhinitis, of which the seasonal type is called hay fever, is a type of inflammation in the nose that occurs when the immune system overreacts to allergens in the air. It is classified as a type I hypersensitivity reaction. Signs a ...
and nonallergic rhinitis. Nasal septum deviation and inferior turbinate hypertrophy (enlargement) are present in almost all cases of snoring and obstructive sleep apnea. Masses in the nasal cavity such as nasal polyps or
tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
may also cause snoring.


Adenotonsillar hypertrophy

Adenoid hypertrophy (enlargement of the adenoid tonsil) and tonsillar hypertrophy (enlargement of the
palatine tonsil Palatine tonsils, commonly called the tonsils and occasionally called the faucial tonsils, are tonsils located on the left and right sides at the back of the throat in humans and other mammals, which can often be seen as flesh-colored, pinkish ...
s) is associated with snoring and obstructive sleep apnea, especially in children since the tonsils are larger at younger ages. Adenotonsillar hypertrophy is the most common cause of snoring in children.


Mouth

Dental problems may be conditions associated with snoring rather than direct causes. Examples include malocclusion, crowding of upper teeth, a narrow
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...
, and a high-arched palate. Narrow palate and high-arched palate create a predisposition to chronic nasal obstruction.


Mouth breathing

Mouth breathing frequently accompanies snoring as one of main features of sleep-related breathing disorders (including primary snoring, upper airway resistance syndrome, and obstructive sleep apnea). In one study, 18% of people with mouth breathing reported awareness of snoring.


Retrognathia

Retrognathia (receded lower jaw) is more common in obstructive sleep apnea than in primary snoring. Micrognathia (small jaw size) is also linked to snoring.


Pharynx

The muscles of the pharynx relax during sleep, causing partial airway obstruction. The oropharynx is a common site which causes snoring noises.


Tongue

When sleeping on the back, gravity pulls the tongue backwards and may obstruct the airway. An enlarged tongue, termed macroglossia, is a potential cause for snoring. Obesity may result in increased tongue size. The base of the tongue may be enlarged and cause snoring, e.g. because of a
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
.


Larynx and laryngopharynx

Problems within the
larynx The larynx (), commonly called the voice box, is an organ (anatomy), organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal ...
("voice box") and laryngopharynx may cause snoring, such as laryngeal stenosis or an omega-shaped epiglottis.


Obstructive sleep apnea

Snoring is one of the cardinal symptoms of obstructive sleep apnea. People who snore are five times more likely to have obstructive sleep apnea compared to those who don't snore. Snoring is common in upper airways resistance syndrome, and obstructive sleep apnea is almost always associated with snoring.


Obesity

Being obese or
overweight Being overweight is having more body fat than is optimally healthy. Being overweight is especially common where food supplies are plentiful and lifestyles are sedentary. , excess weight reached epidemic proportions globally, with more than ...
increases the amount of
fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...
around the throat. It is not just body mass index that is important, but the circumference of the neck (e.g., collar size more than ) and the size of the tongue. Obesity hypoventilation syndrome also involves snoring.


Alcohol

Alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...
causes muscle relaxation via its
depressant Depressants, also known as central nervous system depressants, or colloquially known as "downers", are drugs that lower neurotransmission levels, decrease the electrical activity of brain cells, or reduce arousal or stimulation in various ...
effect on the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
. This muscle relaxation seems to be more pronounced for the tongue, which may then be more prone to obstruct the airway.


Muscle relaxants

Medications that cause muscle relaxation, such as
sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or Psychomotor agitation, excitement. They are central nervous system (CNS) Depressant, depressants and interact with brain activity, causing its decelera ...
s and
hypnotic A hypnotic (from Ancient Greek, Greek ''Hypnos'', sleep), also known as a somnifacient or soporific, and commonly known as sleeping pills, are a class of psychoactive drugs whose primary function is to sleep induction, induce sleep and to trea ...
s, may cause snoring or make it worse. One example is
diphenhydramine Diphenhydramine, sold under the brand name Benadryl among others, is an antihistamine and sedative. Although generally considered sedating, diphenhydramine can cause paradoxical central nervous system stimulation in some individuals, particula ...
.


Diet

Magnesium is a
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
which may have a role in maintaining
circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...
and sleep quality. There may be a connection between higher magnesium intake and sleep quality, which includes factors such as snoring, daytime sleepiness, and sleep duration. One study supported this connection. Another study showed that 332.5 mg/day magnesium did not have any effect on sleep symptoms such as snoring and sleepiness.


Pregnancy

Sometimes snoring starts during
pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...
.


Hereditary factors

Some people have a genetic predisposition to snoring, a proportion of which may be mediated through other heritable lifestyle factors such as body mass index, smoking and alcohol consumption. The DLEU1 gene (part of BCMS) has been linked to snoring.


Possible consequences

Most people with primary snoring do not have any significant health problems as a result of the snoring. Typically, associations with other health conditions are better understood and researched for obstructive sleep apnea than for primary snoring without obstructive sleep apnea.


For sleeping partner

It is sometimes suggested that snoring is more of a problem for the sleeping partner than the person who snores. Snoring of one partner may cause marital discord, and sometimes has even lead to a divorce. The term "snoring spouse syndrome" has been used to describe the health effects for sleeping partners of people with obstructive sleep apnea. Snorers may be unaware of their snoring. It may be difficult for sleeping partners to adjust to the noise because snoring may be irregular, changing in volume and character. This may wake them and prevent them from falling asleep again. Sleeping partners may try to nudge the snorer. This may trigger the snorer to change position, or it may rouse them sufficiently to reduce the muscle relaxation in the upper airway, lessening the snoring. Partners of snorers may use other strategies to minimize the impact of snoring such as
earplug An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Earplugs may be used as well to improve sleep quality or focus in noisy environments ...
s, going to sleep at a different time, or sleeping in a different room. In one study, treatment of snoring in males (with continuous positive airway pressure) resulted in 13% better sleep efficiency and an average of 1 hour of extra sleep for their female sleeping partners. One hour of lost sleep per day equates to a whole night of lost sleep each week. This may result in chronic
sleep deprivation Sleep deprivation, also known as sleep insufficiency or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either Chronic (medicine), chronic ...
for sleeping partners of snorers. It has also been reported that sleeping partners of snorers may gradually develop
hearing loss Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spo ...
, although there is little evidence for this. In one small study, sleeping partners had detectable hearing loss in the ear that was habitually facing the snorer. Parents of children who snore may also suffer reduced sleep quality.


Cognitive and psychological

Snoring may cause sleep deprivation for snorers. Snoring, even when not associated with obstructive sleep apnea, has been linked to excessive daytime sleepiness. Snoring may cause other problems such as irritability, depression, memory loss,
fatigue Fatigue is a state of tiredness (which is not sleepiness), exhaustion or loss of energy. It is a signs and symptoms, symptom of any of various diseases; it is not a disease in itself. Fatigue (in the medical sense) is sometimes associated wit ...
, lack of focus and decreased libido. It has also been suggested that it increases the risk of road traffic accidents. In children, snoring may affect growth. It may also affect mood, attention, intelligence, and reduce academic performance at school. Snoring may manifest as behavioral problems, hyperactivity, and impulsivity.


Cardiovascular disease

Some studies report that there is a higher prevalence of
cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...
in snorers. This includes
metabolic syndrome Metabolic syndrome is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Metabolic syndro ...
,
hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...
(high blood pressure), and
atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...
, There may be up to a 46% increased risk of
stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...
, and 28% increased risk of
coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of cardiovascular disease, heart disease involving Ischemia, the reduction of blood flow to the cardiac muscle due to a build-up ...
/ ischemic heart disease (probably in part explained by snoring with obstructive sleep apnea). Snoring causes increased inspiratory effort. This may increase the circulatory load on the heart. Impaired balance between the sympathetic and parasympathetic nervous system may also be involved. Smoking may cause intermittent hypoxia,
oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...
, and inflammation. These processes may damage the
endothelium The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the r ...
(the lining of blood vessels). In addition to the above factors, sleep apnea may cause insulin resistance, dysfunction of endothelium,
diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...
,
dyslipidemia Dyslipidemia is a metabolic disorder characterized by abnormally high or low amounts of any or all lipids (e.g. fats, triglycerides, cholesterol, phospholipids) or lipoproteins in the blood. Dyslipidemia is a risk factor for the development of ...
, and hypertension. However, not all studies report increased risk of cardiovascular disease in those who snore. There is limited evidence that snoring may cause atherosclerosis of the carotid artery. In research on animals, vibration energy from snoring may be transmitted to the carotid artery. This vibration causes damage to the endothelium. The binding ability of low density lipoprotein may also be increased by acoustic waves. In other words, vibrations from snoring may damage blood vessels, cause formation of atherosclerotic plaque, and also increase the probability that the plaque ruptures. Both non apneic snoring and snoring associated with obstructive sleep apnea have been correlated with carotid atherosclerosis, carotid artery stenosis, and other carotid disease in humans. In one study, snorers had 50% higher chance of carotid stenosis and were more likely to have carotid disease on both the left and right sides. Snoring that starts during pregnancy may be linked with higher risk of
gestational hypertension Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks of gestation without the presence of protein in the urine or other signs of pre-eclampsia. Gestational hype ...
and preeclampsia.


Headaches

Snoring is also linked to
headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...
s and migraines, especially headache upon waking. This may be related to
cerebral hypoxia Cerebral hypoxia is a form of Hypoxia (medical), hypoxia (reduced supply of oxygen), specifically involving the human brain, brain; when the brain is completely deprived of oxygen, it is called ''cerebral anoxia''. There are four categories of c ...
,
hypercapnia Hypercapnia (from the Greek ''hyper'', "above" or "too much" and ''kapnos'', "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous pro ...
, and temporary increased intra-cranial pressure. Snoring is associated with respiratory event-related arousals, which may be connected with headache.


Gastroesophageal reflux disease

Snoring and obstructive sleep apnea are associated with higher rates of
gastroesophageal reflux disease Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is a chronic upper gastrointestinal disease in which stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/or ...
, including acid reflux which occurs during sleep. There is increased negative pressure in the thoracic cavity during apneic episodes. It was suggested that this negative pressure may overcome the lower esophageal sphincter and allow stomach contents to reflux into the
esophagus The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...
. However, the lower esophageal sphincter was found to be stronger during obstructed breathing events. Another theory which explains the connection is that snoring and obstructive sleep apnea may promote transient lower esophageal sphincter relaxations. Enlarged tonsils are also seen in gastroesophageal reflux disease, and this may contribute to airway restriction and snoring.


Sleep bruxism

There is conflicting evidence for and against a possible connection between snoring and sleep bruxism (teeth grinding during sleep). It may be that in snoring and obstructive sleep apnea, there are periods of activation of oropharyngeal muscles. These are necessary to restore patency of the collapsed / obstructed airway. This muscle activity may also trigger activity in the muscles of mastication and hence sleep bruxism.


Dry mouth

There is limited and contradictory evidence for a connection between snoring and xerostomia (dry mouth). Tissue biopsies of the uvula have been carried out on heavy snorers and people with severe obstructive sleep apnea. The biopsies showed abnormal minor salivary glands. There was increased volume of mucous salivary glands and reduced quantity and volume of serous salivary glands. This may cause reduced production of
saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...
. Snorers also tend to breathe through their mouths during sleep, in order to get more air. This may have a drying effect in the mouth.


Other

Nerve damage may occur in the soft palate as a result of chronic trauma from vibration. This is leads to morphological changes in the palate.


Diagnosis

According to ICSD-3, primary snoring may diagnosed with the following diagnostic criteria: * Affected individual or sleeping partner reports breath sounds associated with breathing in during sleep. * No other sleep disorder that could be causing the snoring. * Diagnostic investigations such as polysomnography do not show another sleep related respiratory disorder. Questioning of not just the snorer but also their sleeping partner may be useful in the diagnostic process. The following parameters may be recorded: snoring frequency (less than 3 nights per week or every night), loudness, character (regular or irregular pattern), associated with inhalation or exhalation, and whether the snoring is associated with certain sleeping positions. Any aggravating factors may be identified, such as alcohol, smoking, or nasal congestion. Associated symptoms may be identified, such as insomnia, breathing pauses during sleep, waking with difficulty breathing, dry mouth, daytime sleepiness, and poor concentration. Any history of potentially related conditions may be recorded, such as cardiovascular disease, obesity, and diabetes. It is sometimes useful if the individual or their sleeping partner provides an audio recording of the snoring. Audio recordings may highlight apnea. Palatal snoring (caused by vibration of the soft palate) has an average peak frequency of 137 hertz. Snoring caused by the tongue base has 1243 Hz. Combined palatal and tongue snoring has 190 Hz. Snoring caused by epiglottis has 490 Hz.
Physical examination In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ...
is normally carried out. The morphology of the facial skeleton is noted. Examination of the nasal cavity may be done with anterior rhinoscopy and nasal
endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...
, which may identify problems inside the nose such as deviated septum, hypertrophic inferior turbinate, or nasal polyps. The mouth and teeth are also examined. The oropharynx may be examined with flexible transnasal endoscope (through the nose) or rigid transoral endoscope (through the mouth). If laryngeal snoring is suspected, laryngoscopy or drug-induced sleep endoscopy may be carried out. The latter investigation enables examination of the upper respiratory tract while the patient is unconscious. Bronchoscopy may also be carried out. To diagnose primary snoring, it is necessary first to rule out obstructive sleep apnea and all other sleep-related respiratory disorders. This usually requires an overnight sleep study (polysomnography), which is the
gold standard A gold standard is a backed currency, monetary system in which the standard economics, economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the ...
in investigation and diagnosis of sleep disorders. A sleep study includes calculation of the apnea–hypopnea index, and measurement of many other parameters such as the total number of snoring events, flow limitations without snoring (indicates nasal obstruction), and flow limitation with snoring (indicates obstruction from palate and tongue base). Home sleep apnea test is another option, allowing calculation of apnea-hypopnea index and respiratory disturbance index and differentiation between primary snoring and obstructive sleep apnea. Other investigations may sometimes be done, such as nasal function testing (e.g., rhinomanometry), pharyngeal manometry, allergy testing, acoustic analysis, or
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...
.


Treatment

Almost all treatments for snoring revolve around lessening the noise and improving air flow by reducing the blockage in the airway.


Lifestyle modification

Lifestyle changes are a first-line treatment to stop snoring. Recommended lifestyle changes include stopping
smoking Smoking is a practice in which a substance is combusted, and the resulting smoke is typically inhaled to be tasted and absorbed into the bloodstream of a person. Most commonly, the substance used is the dried leaves of the tobacco plant, whi ...
, avoiding alcohol before bedtime, and sleeping on the side (lateral position). Sleeping on the side reduces the tendency for the base of tongue to fall back and obstruct the airway. This occurs when sleeping on the back (supine position) since gravity pulls the tongue backwards in this position. Losing weight reduces the amount of fat that compresses the airway. Even a modest amount of weight loss, such as 4.5 kg (10 lbs) can improve snoring. Improving
sleep hygiene Sleep hygiene is a behavioral and environmental practice developed in the late 1970s as a method to help people with mild to moderate insomnia. Clinicians assess the sleep hygiene of people with insomnia and other conditions, such as depressio ...
may be beneficial. Examples include establishing fixed routines for bedtime and wake up time, including on weekends. Relaxation before sleep may help people get to sleep more quickly. Applications for smartphones and smartwatches are available. They often record snoring during sleep, compare snoring severity over time, and give advice to users. Some apps trigger a sound or vibration when the person starts to snore. Many over-the-counter snoring treatments, such as stop-snoring rings or wrist-worn electrical stimulation bands, have no scientific evidence to support their claims.


Nasal strips and dilators

Many types of nasal strips, nose clips, and internal dilators are available to temporarily prevent nasal valve collapse. They are all designed to stent and expand the internal nasal valve.


Orthopedic pillows

Orthopedic pillows are designed to support the head and neck in a way that ensures the jaw stays open and slightly forward. This helps keep the airways unrestricted as possible and in turn leads to reduced snoring. A pillow that was designed to change the position of the head was found to reduce snoring intensity both subjective and objectively (with polysomnography).


Medications

Medications are usually not helpful in treating snoring symptoms, though they can help control some of the underlying causes such as nasal congestion and allergic reactions.
Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...
nasal sprays and drops can reduce inflammation in nasal mucosa and reduce the size of the adenoid, thereby reducing symptoms of obstructive sleep apnea such as snoring. Montelukast has also been used in the same application. Systemic medication and oils and sprays for the mouth are not recommended. A temporary period of nasal decongestants may allow for simulation of the potential effect of surgery on the nasal concha in that individual. Medications that aggravate snoring such as sedatives may be avoided before bedtime, or they may be substituted for weaker alternatives.


Myofunctional therapy (oropharyngeal exercises)

Myofunctional therapy (also termed myofascial therapy) incorporates oropharyngeal (mouth and throat) and tongue exercises. The exercises are usually combinations of isotonic and isometric exercises involving different muscles of the soft palate, tongue, face, pharynx, jaw, and upper respiratory tract. Pronouncing vowel sounds activates muscles in the soft palate and uvula. Tongue exercises may involve movement of the tongue in different directions, sticking out the tongue, and pressing the tongue against hard and soft tissue surfaces in the mouth. Facial exercises may involve pushing out the cheek with a finger while puckering, closing, or moving the lips. Jaw exercises may involve chewing and opening and closing the mouth. Pharyngeal exercises may involve swallowing. Other exercises include sucking through a narrow straw and blowing up balloons. Myofunctional therapy is theorized to improve the tone and positioning of the muscles. The exercises may promote a closed mouth breathing position where the tongue is in contact with the palate. This may create negative pressure in the mouth, leading to a stabilization of patency of the pharynx and reduced muscular effort required to keep the airway open. There is conflicting evidence for the effectiveness of myofunctional therapy in snoring. One systematic review found that myofunctional therapy reduces snoring in adults based on both subjective questionnaires and objective sleep studies. Snoring intensity was reduced by 51%. Time spent snoring was reduced by 31% as measured by polysomnography. One study used objective measurement of snoring (audio recordings) and found that myofunctional therapy had little to no effect in reducing snoring frequency. Another study reported that myofunctional therapy had a possible reduction in snoring frequency and intensity (measured subjectively) compared to sham therapy (placebo). When myofunctional therapy combined with CPAP is compared to myofunctional therapy alone, there may be little to no difference. There is insufficient evidence to recommend myofunctional therapy for snoring in adults. Myofunctional therapy may be more useful in children who snore than in adults.


Dental appliances

Dental appliances are common treatments for snoring. They may be custom made, which requires an impression of the teeth and construction in a dental laboratory, or they may be bought over the counter without involvement of a dental health professional. The latter type are often "boil and bite" appliances which come in a set size. The appliance is immersed in boiling water and then the individual bites into appliance with the jaw in a protruded position. Oral appliances may be titratable (adjustable) or non-titratable (one fixed position). In general, oral appliances are cheap and non-invasive. They can be combined with CPAP treatment. Complications include discomfort, excessive
saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...
tion (drooling), insomnia, pain in the periodontal ligament of teeth if they are under excessive force, pain in the
temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral Synovial joint, synovial articulation between the temporal bone of the skull above and the condylar process of mandible be ...
and
muscles of mastication The four classical muscles of mastication elevate the mandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the geniohyoid, mylohyoid, an ...
(e.g. temporalis), and jaw dislocation. Some devices prevent anterior oral seal, and therefore cause mouth breathing with the associated problems like dry mouth. A device which covers only some of the teeth and leaves others uncovered may potentially have a Dahl effect, leading to undesired movement of the teeth and creating problems like open bite. Therefore, a dentist should regularly review individuals who are using dental appliances for snoring. Mandibular advancement splints (mandibular repositioning splints) push the lower jaw forwards. The tongue has muscular connections to the mandible and therefore is pulled forwards at the same time, which prevents obstruction of the airway at the oropharynx. This is a similar mechanism to the jaw-thrust maneuver used to maintain patency of a supine patient in first aid. In addition, mandibular advancement splints increase the tension in the soft palate and pharyngeal walls. Mandibular advancement splints are used for snoring and for mild to moderate obstructive sleep apnea. They may be useful for people with retrognathia (receded lower jaw). Mandibular advancement splints are better tolerated than CPAP. They can reduce snoring loudness and improve quality of life of snorers and their sleeping partners. Tongue repositioning (retaining) devices are made of soft acrylic and cover the upper and lower teeth and create a seal with the lips. They have a "bulb" or "bubble" which sticks out the front of the mouth. This creates negative suction pressure, holding the tongue in a forward position and increasing the airway space behind the tongue. Soft-palate lifters are devices which lift the soft palate. They are useful for people who have weak muscles in the region.


Orthodontic treatment

Orthodontic treatment may improve some dental problems associated with snoring, such as a narrow palate.


Positive airway pressure

Continuous positive airway pressure (CPAP) is a machine which pumps air through a flexible hose to a mask worn over the mouth, nose, or both. The pressure of the air keeps the airway open. CPAP is considered the gold standard treatment for obstructive sleep apnea. It has been shown to reduce snoring associated with obstructive sleep apnea. However, CPAP can be uncomfortable, and many people stop using it. This is especially true for primary snoring.


Surgery

Surgical procedures outside the nose and soft palate for treatment of primary snoring have been discouraged. Many different surgical procedures have been used for snoring, including: * Nasal surgeries, e.g. septoplasty, turbinoplasty, various procedures for nasal valve collapse (spreader grafts, spreader flaps, butterfly grafts, batten grafts). * Palatal surgeries, e.g. uvulopalatopharyngoplasty (most commonly performed procedure for snoring), palatal implants ( pillar procedure), somnoplasty (may combine other sites) * Adenoidectomy or tonsillectomy (or combined, termed adenotonsillectomy). * Tongue base surgeries * Hypopharyngeal surgery * Orthognathic surgery, e.g. maxillary mandibular advancement * Hypoglossal nerve stimulation * Tracheostomy *
Bariatric surgery Bariatric surgery (also known as metabolic surgery or weight loss surgery) is a surgical procedure used to manage obesity and obesity-related conditions. Long term weight loss with bariatric surgery may be achieved through alteration of gut ho ...


Epidemiology

Snoring is one of the most common sleep disorders. The reported prevalence of snoring varies significantly depending on the population studied, and because there is no universally accepted definition of snoring. Occasional snoring is almost universally present in humans. Habitual (primary snoring) is less common but still a common problem. Snoring affects 2.6–83% of males and 1.5–71% of females. Snoring is more common in males than females. In research about obstructive sleep apnea, it was found that the upper airway is longer and more collapsible in males, and that fat is distributed differently in males and females Snoring is more common in older people. However, after age 70, awareness of snoring decreases. This is possibly related to hearing loss. Snoring also has positive correlations with larger body-mass index, lower socio-economic status, and more frequent smoking and alcohol consumption. Snoring affects about 8–12% of children.


Society and culture

There are descriptions of snoring in the fifteenth century. Uvulopalatopharyngoplasty was proposed in 1964 by Ikematsu as a treatment for snoring.Ikematsu, T (1964). "Study of snoring". Therapy. ''J Jpn Otol Rhinol Laryngol Soc'' 64: 434–435 CPAP was first used for snoring and obstructive sleep apnea in 1981. Compared to obstructive sleep apnea, primary snoring has received less attention in research. Snoring is sometimes not considered as a medical condition by medical insurance companies, meaning that treatments may not be covered by insurance. " Zzz" is a common onomatopeic representation of snoring. It may have developed from use in comics.


References


External links

{{Authority control Sleep disorders Symptoms and signs: Respiratory system