It is estimated that about 40 percent of adult men and 24 percent of adult women are regular snorers [1]. 

1. Is Snoring Dangerous?

Although snoring is harmless, it can also be due to a serious health issue when it is associated with obstructive sleep apnea and chronic diseases, such as type II diabetes and high cholesterol.

2. What Are the Causes of Snoring?

Snoring can be due to lifestyles such as smoking, consumption of alcohol and sedatives, or sleep positions but it can also be associated with genetics such as inherited genes that shape the head and neck anatomy of an individual.

Snoring can also be associated with conditions including chronic nasal congestion, obstructive sleep apnea, and hypothyroidism.

• Snoring and Obstructive Sleep Apnea (OSA)

Obstructive Sleep Apnea (OSA) is a condition characterized by intermittent episodes of partial or complete obstruction of the airways due to soft tissue falling at the back of the throat (Upper airway) when sleeping.

It is estimated that approximately 34% of middle-aged men and 17% of middle-aged women are diagnosed with OSA [2].

Obstructive sleep apnea (OSA) can cause cardiovascular diseases through the following mechanisms [3]:

• Sympathetic activation (fight-or-flight response)
• Intrathoracic pressure changes that limit heartbeat
• Oxidative stress causing tissue damage
• Abnormalities in coagulation factors
• Endothelial damage (damage to the blood vessels)
• Inflammatory mediators that lead to defects in the formation of vessels.

• Snoring and Head and Neck Anatomy

The shape of the head and face, the anatomy of the upper airway, and the circumference of the neck are predictors of sleep apnea and snoring in individuals [4].

A large tongue, craniofacial abnormalities, a receding chin, and a small jaw are associated with the reduction of the size of the upper airway which increases the risk of sleep apnea and snoring.

A neck circumference that is higher than 16.5 inches is also a risk factor for sleep apnea and snoring.

Abnormalities in cells that control breathing known as chemoreceptors can also reduce the size of the upper airway.

These anatomical characteristics may be due to inherited genes responsible for increased risk of sleep apnea and snoring [5].

• Snoring and Alcohol

Alcohol consumption increases the relaxation of soft tissues in the upper airway causing sleep apnea and snoring.

A study showed that alcohol consumption increases the severity of snoring, sleep apnea, and the levels of oxygen in blood and tissues (Hypoxia) [6].

• Snoring and Sedatives

Analgesics, anesthetics, opioids, and sedatives can also increase the relaxation of the tongue and soft tissues in the upper airway resulting in sleep apnea and snoring [7].

• Snoring and Smoking

Cigarette smoke can irritate and inflame the nasal cavity and the upper airway making them swell which reduces the capacity of breathing.

Another cause may be associated with nicotine withdrawal during sleep that causes sleep instability that increases the risk of sleep apnea and snoring [8].

• Snoring and Sleep Position

Sleeping on the lateral side is the best position while sleeping on the back is likely to increase sleep apnea and snoring.

This difference is due to gravity that increases the tendency for the tongue and soft tissues to fall to the back of the throat causing obstruction of the upper airway [9].

• Snoring and Chronic Nasal Congestion

Chronic Nasal Congestion is characterized by inflammation and swelling of the nasal cavity and the sinuses that lasts for more than 3 months and resulting in reduced breathing through the nose.

Chronic Nasal Congestion can be caused by sinusitis, nasal polyps, allergic rhinitis, or a deviated nasal septum (wall between the nasal cavities).

A study found that nasal congestion during sleep is a strong risk factor for habitual snoring [10].

• Snoring and Aging

The relaxation of the muscles of the upper airway is a normal event in aging which explains why it is common in the adult population.

However, persistent snoring is an indicator of a potential reduction of oxygen levels in blood and tissue (Hypoxia) associated with sleep apnea.  Persistent hypoxia may increase the process of aging by promoting hallmarks of aging such as stem cell exhaustion, telomere attrition, and epigenetic changes [11].

• Snoring and Being Overweight

Being overweight or out of shape can reduce muscle tone and increase fat deposition around the neck and throat that can promote the obstruction of the upper airway causing sleep apnea and snoring.

• Snoring and Hypothyroidism

Hypothyroidism is a disorder associated with reduced production of the thyroid hormones resulting in symptoms such as weight gain, fatigue, depression, and slow heart rate [12].

Another important characteristic of hypothyroidism is the enlargement of the thyroid known as goiter (neck looking enlarged) that can interfere with breathing by obstructing the upper airway causing sleep apnea and snoring.

3. Why Do I Snore Loud?

Sounding loud is associated with a higher obstruction of the upper airway. The more it is obstructed the more is the breathing difficulty, and therefore, the louder is the snoring.

4- How Is snoring Tested?

• Home Sleep Apnea Test

Portable devices are used to measure the breathing and blood oxygen level while you sleep.

• In-lab sleep study

This is performed in a sleep center where brain waves, breathing, eye movements, blood oxygen, heartbeats, and limb movements are measured.

5. What Are the Best Snoring Solutions?

Snoring can be reduced by tackling the causes that are outlined above.

• Lifestyle changes

– Reducing or stopping alcohol consumption can significantly prevent sleep apnea and snoring.

– Sleeping on the lateral side can reduce snoring.

– In addition to other benefits for health, quitting smoking can also gradually prevent or reduce snoring.

– Losing weight through a healthy diet and exercise.

– Avoiding tranquilizers and sleeping pills.

• Treatment of allergies

Allergies can cause chronic nasal congestion, and therefore, medications that reduce allergies can prevent snoring.

• Surgery

To restore a normal breathing pattern during the night surgery is performed on the nose or the back of the throat.

• Continuous Positive Airway Pressure (CPAP)

This is performed using a device that gently blows room temperature air through a mask or mouthpiece to the back of the throat to prevent breathing pauses.

• Oral Appliance Therapy

This therapy involves the use of a removable oral device and is recommended for individuals who cannot tolerate CPAP and whose OSA is moderate or mild.

Conclusion

Snoring increases with age and can be due to lifestyle which can be reversed by making changes in sleep position, avoiding alcohol and smoking, and having a healthy diet; however, it can become serious and lead to chronic diseases such as cardiovascular diseases and type II diabetes if untreated.

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• Sympathetic activation
• Intrathoracic pressure changes
• Oxidative stress
• Abnormalities in coagulation factors
• Endothelial damage
• Inflammatory mediators

Approximately 34% of middle-aged men and 17% of middle-aged women are diagnosed with OSA [1]. The prevalence of OSA is estimated at 40% to 80% in patients with hypertension, coronary artery disease, heart failure (HF), atrial fibrillation (AF), pulmonary hypertension (PH), and stroke [2].

What Is Sleep Apnea?

Sleep apnea is a sleep disorder that is characterized by pauses in breathing or shallow breaths during sleep. These pauses can last for several seconds to minutes and can occur 30 times or more per hour.

Each pause in breathing reduces the amount of oxygen that reaches the brain, which can lead to snoring, interrupted sleep, and excessive daytime sleepiness. Sleep apnea is a serious medical condition that can significantly impact the quality of life.

1- Sympathetic activation

The sympathetic nervous system is a part of the autonomous nervous system responsible for the fight-or-flight response. Its repetitive activation by apnea results in increased systolic blood pressure that leads to hypertension and its complication with time [3]. Repetitive apnea may also lead to an autonomic imbalance and reduced heart rate variability [4].

Treatment with nasal continuous positive airway pressure (CPAP) has been shown to reduce blood pressure during the day and night. CPAP treatment of patients with sleep apnea and heart failure or congestive heart failure resulted in the reduction of systolic blood pressure and an improvement of the left ventricular systolic function [5]

2- Intrathoracic pressure changes

Due to the anatomical location of the heart and lungs in the thoracic cage, the interactions between the two are frequent.

Although both heart and lungs occupy limited spaces within the thoracic cage, the breathing dynamic of the lungs results in changes in the space it occupies, and therefore, affects the space occupied by the heart.

These breathing dynamics result in changes in the external constraint of the heart function, blood volume redistribution, direct systolic ventricular interaction (increased pressure by the pericardium), and afterload of the left ventricular.

An increased intrathoracic pressure limits the ventricular diastolic loading resulting in increased direct ventricular interaction, which may limit the filling of the left ventricle [6]. This interaction between the heart and the lungs may explain the association between sleep apnea and cardiovascular morbidity.

3- Oxidative Stress, Inflammatory Mediators, and Endothelial Damage

Hypoxia is a condition associated with a decrease in the level of oxygen available to the body’s tissues. This condition is commonly observed in patients with sleep apnea [7].

Hypoxia triggers an inflammatory response and an increase in innate immune cells such as neutrophils. These cells secrete reactive oxygen species (ROS) or destructive proteinases that are responsible for tissue damage, including damage to the tissues of the cardiovascular system [8].

Neutrophils also activate the transcription factor HIF-1 (Hypoxia Inducible Factor 1) which promotes the activation of endothelial cells, which are essential for the formation of the blood vessels. However, during hypoxia, endothelial cells express adhesion molecules and proinflammatory cytokines that result in endothelial damage leading to defects in vascular formation [9].

4- Abnormalities in coagulation factors

Blood platelets play an essential role in coagulation, thrombosis, and wound healing. During hypoxia, HIF-1 can promote the activation of platelets, and therefore, increase their blood content [9].

Several studies have shown a strong correlation between the increase in platelets, thromboembolic complications, and worse outcomes of cardiovascular events. It was also reported that blood viscosity due to platelet reactivity is increased in patients with OSA in the morning [10].

5- Potential Factors Influencing the Relationship Between Sleep Apnea and Cardiovascular Diseases

Metabolic syndrome comprises related diseases such as obesity, hypertension, diabetes, and dyslipidemia (abnormal cholesterol or triglyceride levels). Having one of these conditions significantly increases the risk of serious disease, including cardiovascular morbidity and mortality from coronary heart disease and stroke.

Several studies investigated the relationship between sleep apnea and diseases related to metabolic syndrome [5].

A study investigated the correlation between obesity and apnea and found that 60% of obese men had sleep-disordered breathing and 27% had obstructive sleep apnea. Another study reported that 60% to 90% of patients with sleep apnea are obese.

Regarding the relationship between sleep apnea and hypertension, a study found that about 40% of patients with sleep apnea suffer from hypertension.

An association between diabetes and sleep apnea was investigated by a study that found that patients with sleep apnea have increased glucose levels and increased insulin resistance.

Although dyslipidemia is a known factor contributing to cardiovascular diseases, a relationship between sleep apnea and dyslipidemia has not yet been established and future studies will certainly investigate a potential association.

Conclusion

Due to the complexity of the factors involved in the relationship between sleep apnea and cardiovascular diseases, the management of patients with OSA requires the involvement of several healthcare professionals including a sleep specialist, cardiologist, primary provider, otolaryngologist, dietitian, neurologist, and pulmonologist. 

Treatments also exist and include CPAP, auto-titrating PAP, bilevel PAP, adaptive servo-ventilation, positional therapy, lifestyle intervention (e.g., weight loss), upper airway surgery, upper airway neurostimulation, oral appliances, and bariatric surgery. Unfortunately, these treatments may prevent OSA but cannot treat some of the underlying causes that require other types of treatments.

References

[1] Peppard, P.E., Young, T., Barnet, J.H., Palta, M., Hagen, E.W. and Hla, K.M., 2013. Increased prevalence of sleep-disordered breathing in adults. American journal of epidemiology, 177(9), pp.1006-1014.

[2] Javaheri, S., Barbe, F., Campos-Rodriguez, F., Dempsey, J.A., Khayat, R., Javaheri, S., Malhotra, A., Martinez-Garcia, M.A., Mehra, R., Pack, A.I. and Polotsky, V.Y., 2017. Sleep apnea: types, mechanisms, and clinical cardiovascular consequences. Journal of the American College of Cardiology, 69(7), pp.841-858.

[3] Fletcher, E.C., 2003. Sympathetic over activity in the etiology of hypertension of obstructive sleep apnea. Sleep, 26(1), pp.15-19.

[4] Guzzetti, S., Piccaluga, E., Casati, R., Cerutti, S., Lombardi, F., Pagani, M. and Malliani, A., 1988. Sympathetic predominance in essential hypertension: a study employing spectral analysis of heart rate variability. Journal of hypertension, 6(9), pp.711-717.

[5] Jean-Louis, G., Zizi, F., Clark, L.T., Brown, C.D. and McFarlane, S.I., 2008. Obstructive sleep apnea and cardiovascular disease: role of the metabolic syndrome and its components. Journal of Clinical Sleep Medicine, 4(3), pp.261-272.

[6] Verhoeff, K. and Mitchell, J.R., 2017. Cardiopulmonary physiology: why the heart and lungs are inextricably linked. Advances in physiology education, 41(3), pp.348-353.

[7] Friedman, M., Landsberg, R. and Ascher-Landsberg, J., 2001. Treatment of hypoxemia in obstructive sleep apnea. American journal of rhinology, 15(5), pp.311-313.

[8] Williams, A.E. and Chambers, R.C., 2016. Neutrophils and tissue damage: is hypoxia the key to excessive degranulation?.

[9] Lavie, L., 2003. Obstructive sleep apnoea syndrome–an oxidative stress disorder. Sleep medicine reviews, 7(1), pp.35-51.

[10] Toraldo, D.M., Peverini, F., De Benedetto, M. and De Nuccio, F., 2013. Obstructive sleep apnea syndrome: blood viscosity, blood coagulation abnormalities, and early atherosclerosis. Lung, 191(1), pp.1-7.

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