Sleep apnea is a serious, potentially fatal medical condition in which breathing stops and starts repeatedly during sleep. This pattern can repeat itself 10 or more times an hour all night, resulting in serious cardiovascular complications, such as high blood pressure, coronary artery disease, congestive heart failure, stroke and abnormal heart rhythms. (Genesis Health, 2014) THE TWO MAIN TYPES OF SLEEP APNEA Obstructive Sleep Apnea: This is the most common form of the disorder. The throat muscles supporting the soft palate, the uvula (a triangular piece of tissue hanging from the soft palate), the side walls of the throat and the tongue relax, narrowing or obstructing the airway. As you inhale, you’re unable to take an adequate breath, lowering the oxygen level in the blood. Your brain registers this inability and briefly rouses you from sleep so you can reopen your airway.
Central Sleep Apnea: This less common form occurs when the brain sends faulty signals to the muscles controlling breathing. You may have a hard time getting to sleep or staying asleep. Central sleep apnea is usually caused by heart failure or, more rarely, stroke.
COMMON SYMPTOMS OF BOTH TYPES OF SLEEP APNEA
Excessive daytime sleepiness (hypersomnia)
Loud snoring, usually more prominent in obstructive sleep apnea
Episodes of breathing cessation during sleep witnessed by another person
Awakening abruptly with shortness of breath, more likely indicating central sleep apnea
Awakening with a dry mouth or sore throat
Morning headache
Difficulty staying asleep (insomnia)
Attention problems
RISK FACTORS FOR OBSTRUCTIVE SLEEP APNEA
Excess weight: Fat deposits around the upper airway may obstruct breathing.
Neck circumference: People with a thicker neck may have a narrower airway.
A narrowed airway: You may have inherited a naturally narrow throat. Or, your tonsils or adenoids may become enlarged, blocking your airway.
Being male: Sleep apnea occurs twice as frequently in men. However, women increase their risk by being overweight and their risk also rises after menopause.
Being older: Adults over 60 have significantly higher rates of sleep apnea.
Family history: Having family members with sleep apnea increases your risk of having it too.
Smoking: Smokers are three times more likely to have obstructive sleep apnea than people who’ve never smoked. Smoking may increase the amount of inflammation and fluid retention in the upper airway. This risk likely drops after you quit smoking.
Nasal congestion: If you have difficulty breathing through your nose — whether from an anatomical problem or allergies — you’re more likely to develop obstructive sleep apnea.
Race: Among people under 35, the incidence of sleep apnea is higher for blacks.
Use of alcohol, sedatives or tranquilizers: These relax the throat muscles.
RISK FACTORS FOR CENTRAL SLEEP APNEA
Being male: Males are more likely to develop central sleep apnea.
Being older: People older than 65 years of age have a higher risk of central sleep apnea, especially if other risk factors are present.
Heart disorders: People with atrial fibrillation or congestive heart failure are more at risk of central sleep apnea.
Stroke or brain tumor: These conditions can impair the brain’s ability to regulate breathing.
COMPLICATIONS OF SLEEP APNEA
High blood pressure and heart problems: Sudden drops in blood oxygen levels during sleep apnea increase blood pressure, straining the cardiovascular system. Having obstructive sleep apnea increases your risk of high blood pressure (hypertension). The more severe your sleep apnea, the greater the risk of high blood pressure. However, obstructive sleep apnea increases the risk of stroke, regardless of whether or not you have high blood pressure. If there’s underlying heart disease, these multiple episodes of low blood oxygen (hypoxia or hypoxemia) can lead to sudden death from a cardiac event. Obstructive sleep apnea is associated with increased risk of atrial fibrillation, congestive heart failure and other vascular diseases. In contrast, central sleep apnea is usually the result, rather than the cause, of heart disease.
Daytime fatigue: The repeated awakenings associated with sleep apnea make normal, restorative sleep impossible. People with sleep apnea often experience severe daytime drowsiness, fatigue and irritability. You may have difficulty concentrating and find yourself falling asleep at work, while watching TV or even when driving. You may also feel irritable, moody or depressed. Children and adolescents with sleep apnea may do poorly in school or have behavior problems.
Complications with medications and surgery: Obstructive sleep apnea is also a concern with some medications and general anesthesia. People with sleep apnea may be more likely to experience complications after major surgery because they’re prone to breathing problems, especially when sedated and lying on their backs.
Liver problems: People with sleep apnea are more likely to have abnormal results on liver function tests and their livers are more likely to show signs of scarring.
Sleep-deprived partners: Loud snoring can keep those around you from getting enough rest and eventually disrupt relationships. A sleep-deprived bed partner may go to another room to be able to sleep.
Memory problems, morning headaches, mood swings or feelings of depression, a need to urinate frequently at night (nocturia) and a decreased interest in sex are commonly associated with sleep apnea.
Children with untreated sleep apnea may be hyperactive and may be diagnosed with attention-deficit/hyperactivity disorder (ADHD).
All the above information is from the Mayo Clinic’s article on sleep apnea.
BODY MECHANISMS OCCURRING IN SLEEP APNEA (Genesis Health, 2012)
Several changes in the body directly affecting the cardiovascular system occur in the body of someone with sleep apnea.
Sympathetic activation: Sleep apnea speeds up the sympathetic nervous system, causing it to release more adrenalin and epinephrine than usual. This stresses the cardiovascular system, increasing heart rate and blood pressure.
Endothelial dysfunction: Decreases in oxygen intake during sleep apnea damage the endothelial lining in the blood vessels. The endothelial cells constrict and fail to redilate, allowing cholesterol and fatty substances to sit on the endothelium, creating plaque formation and coronary artery disease.
Inflammation: Lack of oxygen due to sleep apnea releases inflammatory chemicals in the body. Among these is C-reactive protein, which causes inflammation in the blood vessels. Having a high level of C-reactive protein means you’re more likely to have coronary artery disease.
Oxidative Stress: Nighttime drops in oxygen during sleep increase the release of super-oxides from the blood cells, damaging the cardiovascular system.
Metabolic Syndrome: Metabolic Syndrome is a group of conditions occurring together – high blood pressure, high blood sugar level, excess body fat around the waist or abnormal cholesterol levels – increasing the risk of heart disease, stroke and diabetes. People with sleep apnea have abnormal metabolic markers that cause obesity and insulin resistance. Patients with sleep apnea also have high levels of leptin, which is associated with weight gain.
Changes in intra-thoracic pressure: Upper airway obstruction due to sleep apnea affects the mechanics of the heart. The chest has to struggle to expand to open up the airway, causing negative pressure inside the chest and adversely affecting the cardiovascular system.
OBSTRUCTIVE SLEEP APNEA AND INCREASED INFLAMMATION Researchers are discovering how obstructive sleep apnea causes the development of cardiovascular and other serious complications. Various studies have shown that elevated inflammatory markers in people with obstructive sleep apnea play a pivotal role in causing impaired functioning of the endothelial cells in the vascular system. Vascular endothelial cells form a thin layer lining the interior surface of the entire circulatory system, from the heart, arteries and veins to the smallest capillaries. These cells perform important functions, including fluid filtration, blood vessel tone, hemostasis (retaining blood inside a damaged blood vessel), neutrophil recruitment (summoning white blood cells to an injured area to begin inflammation for healing the damage) and hormone trafficking. (Wikipedia, 2014) Intermittently inadequate oxygen supply to the cells and tissues of the body (hypoxia) is the principal feature of sleep apnea. The type of hypoxia found in sleep apnea, with frequently occurring repetitive short cycles of oxygen de-saturation followed by rapid re-oxygenation, leads to an unhealthy process in which pro-inflammatory substances get over-produced, leading to excess inflammation and tissue destruction. (Kent et al, 2011) (Ryan & McNicholas, 2008)
That there is a relationship between sleep apnea and oxidative stress, metabolic dysfunction and obesity has been known for some time. A recent study demonstrated that treating sleep apnea with continuous positive airway pressure (CPAP) machines significantly reduces levels of two proteins associated with inflammation: tumor necrosis factor and C-reactive protein. (Baessler, 2013) The bottom line is that treating sleep apnea decreases systemic inflammation, reversing some of the chronic problems associated with the disorder – such as heart disease and type-2 diabetes.
Various aspects of inflammation, its consequences for the body and how to reduce it are discussed on numerous pages and posts elsewhere on this site. If you’re interested in reading more, enter INFLAMMATION in the Search Results area at the top right corner of any page or in the Search This Site box at the bottom.
REFERENCES Baessler, A. et al. ((2013). Treatment for sleep apnea by continuous positive airway pressure improves levels of inflammatory markers – a meta-analysis. Journal of Inflammation, 10:1, 13. Genesis Health System. (2012). Sleep Apnea and Heart Disease: Treatment can reduce cardiovascular risk. See http://www.genesishealth.com/news/2012/sleep-apnea-and-heart-disease/ Kent, B.D. et al. (2011). Obstructive sleep apnea and inflammation: relationship to cardiovascular co-morbidity. Respiratory Physiological Neorobiology, 178:3, 475-81. See http://www.ncbi.nlm.nih.gov/pubmed/21439407 Mayo Clinic. (2014). Sleep apnea. Mayoclinic.com. See http://www.mayoclinic.org/diseases-conditions/sleep-apnea/basics/definition/con-20020286 Ryan, S. and McNicholas, W.T. (2008). Intermittent hypoxia and activation of inflammatory molecular pathways in OSAS. Archives of Physiology and biochemistry, 114:4, 261-6. See http://www.ncbi.nlm.nih.gov/pubmed/18946786 Wikipedia. (2014). Endothelium. See http://en.wikipedia.org/wiki/Endothelium
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