What is sleep apnea?

Sleep apnea¹ is a potentially serious sleep disorder² in which breathing repeatedly stops and starts while you are sleeping.

People with sleep apnea often snore loudly and make periodic gasping or snorting noises while sleep is momentarily interrupted. Because sleep apnea interferes with restful sleep, those with the condition may experience excessive daytime sleepiness.

In some cases, sleep apnea is related to other chronic diseases³, such as diabetes, cardiovascular disease, and obesity. Sleep apnea has also been linked to depression—symptoms of depression can sometimes decrease when sleep apnea has been treated and sufficient sleep has been restored.

What is obstructive sleep apnea?

There are three main types of sleep apnea:

• Central sleep apnea occurs when the brain doesn’t send proper signals to the muscles that control breathing during sleep.
• Obstructive sleep apnea, the more common form of the condition, occurs when throat muscles relax.
• Complex sleep apnea syndrome, also referred to as treatment-emergent central sleep apnea, occurs when someone has both obstructive and central sleep apneas.

Obstructive sleep apnea⁴ (OSA), which is far more common than central sleep apnea, involves the muscles in the back of the throat failing to keep the airway open despite efforts to breathe.

This obstruction of the airway usually results in measurable drops in blood oxygen saturation levels, which return to baseline when breathing resumes. The obstructive episodes characteristic of OSA generally end with waking up briefly in order to reopen the airway.

How common is sleep apnea?

Obstructive sleep apnea syndrome (OSAS) occurs in all age groups and both sexes. According to the National Sleep Foundation⁵ (NSF), OSAS affects between 5–20% of the adult population. OSAS peaks in children between 2–6 years of age.

It is difficult to estimate the prevalence of childhood OSAS because of widely varying monitoring techniques; however, the disorder is reported in about 1–3% of children of preschool age and may be as common as affecting 10–20% of children who habitually snore.

However, the NSF notes that OSAS is likely to be under-diagnosed: one survey found that roughly one-third of adults in a primary care clinic population reported symptoms of OSAS.

Sleep apnea causes

Sleep apnea is caused by both physiological and lifestyle factors.

While obstructive sleep apnea occurs when the muscles in the back of the throat relax, central sleep apnea occurs when the brain fails to transmit signals to the breathing muscles. This causes you to make no effort to breathe for a short period of time, possibly causing you to awaken with shortness of breath or making it difficult for you to fall or stay asleep.

The physical causes of obstructive sleep apnea include being overweight, having abnormal chin or palate features, and having a large neck size (larger than 16” in women and 17” in men). Smoking, alcohol use, ethnicity, and age also contribute to OSA. The condition has also been identified as running in families, suggesting a genetic basis for OSA.

Risks for sleep apnea

The likelihood of developing obstructive sleep apnea and central sleep apnea is increased by a different set of risk factors.

Some factors⁶ that increase the risk of OSA (obstructive sleep apnea) include:

• Excess weight: Excess body weight and obesity are primary risk factors for OSA, especially if fat deposits center around the trunk of the body.
• Physical features: Certain body types are associated with OSA, such as a narrowed upper airway; large tongue, tonsils, or uvula; recessed chin; a small jaw or large overbite; and larger neck sizes (17” or greater in men and 16” or greater in women).
• Demographics*⁷: OSA is more common among men (2–3 times more likely to have sleep apnea than women) and post-menopausal women than other groups. Certain racial and ethnic groups have also been shown to be at higher risk of having OSA, including African-Americans, Pacific Islanders, and Hispanics.
• Age: Sleep apnea is significantly more common in older adults: it is more common among those aged 40 and older and increases significantly after age 60.
• Family history and genetics: As OSA seems to run in families, the condition may have a possible genetic basis. You may be at increased risk of having the condition if you have one or more family members with sleep apnea.
• Alcohol, sedative, or tranquilizer use: These substances relax the upper airways and breathing muscles, which can worsen OSA.
• Smoking: Smokers are 3 times more likely to have OSA than people who have never smoked, as smoking can increase the amount of inflammation and fluid retention in the upper airway.
• Nasal congestion: If you have difficulty breathing from your nose (whether from anatomical problems or allergies), you’re more likely to develop obstructive sleep apnea.

While the condition is far less common than OSA, some risk factors for central sleep apnea include:

• Age: Middle-aged and older people are at a higher risk of central sleep apnea than younger people.
• Being male: Central sleep apnea is more common in men than in women.
• Heart disorders: Congestive heart failure increases the risk of having central sleep apnea.
• Stroke: Having had a stroke increases the risk of central sleep apnea.
• Narcotic pain medications: Opioid medications, especially long-acting ones such as methadone, increase the risk of developing central sleep apnea.

Complications from sleep apnea

Sleep apnea is a serious disease and can cause a number of complications, ranging from being bothersome to requiring medical attention.

Some complications associated with sleep apnea include:

• Daytime sleepiness: The disrupted sleep caused by sleep apnea may make normal, restorative sleep impossible, leading to fatigue and drowsiness during the daytime. You may have difficulty concentrating while doing things like working, reading, or driving. People with sleep apnea have an increased risk of motor vehicle and workplace accidents⁸. Children and adolescents with sleep apnea might have trouble focusing or perform poorly in school.
• High blood pressure or heart problems: Having obstructive sleep apnea increases your risk of having high blood pressure (hypertension⁹). The sudden drops in blood oxygen levels that occur during obstructive episodes increase blood pressure and put a strain on the cardiovascular system. OSA might also increase your risk for recurrent heart attacks, stroke, and abnormal heartbeats.
• Type 2 diabetes: Having sleep apnea increases your risk of developing insulin resistance and type 2 diabetes¹⁰.
• Metabolic syndrome: Metabolic syndrome¹¹ denotes a cluster of the following conditions— high blood pressure, abnormal cholesterol levels, high blood sugar, and an increased waist circumference. Having metabolic syndrome can increase a person’s risk of heart attack or stroke.
• Complications with medications and surgery: OSA can cause complications with certain medications and general anesthesia. People with sleep apnea may be more likely to have complications after major surgeries because of their being prone to breathing problems—especially when sedated and lying on their backs. It’s important to let your healthcare provider know about your sleep apnea and how it’s being treated before undergoing surgery.
• Liver problems: People with sleep apnea are more likely to show abnormal results on liver function tests, and their livers are more likely to show signs of scarring (nonalcoholic fatty liver disease¹²).
• Sleep-deprived partners: The loud snoring characteristic of sleep apnea can keep others who sleep near you from getting a good night's sleep. Not uncommonly, people whose partners have sleep apnea tend to sleep separately in another part of the house.

Sleep apnea symptoms

As the interruption of regular breathing or obstruction of the airway during sleep can pose serious health risks, the symptoms¹³ of sleep apnea should be taken seriously.

Signs and symptoms of both obstructive and central sleep apnea can overlap, making it difficult to determine which specific type of apnea you may have.

The most common symptoms of both obstructive and central sleep apnea include:

• Loud snoring
• Episodes of stopped or interrupted breathing during sleep (this would be reported by another person who observes your episodes)
• Gasping for air during sleep
• Waking up with a dry mouth
• Morning headaches
• Difficulty falling or staying asleep (insomnia¹⁴)
• Excessive daytime sleepiness (hypersomnia¹⁵)
• Difficulty paying attention while awake
• Irritability

While loud snoring can indicate a potentially serious problem, not everyone who has sleep apnea snores.

It’s important to seek medical care if you suspect yourself of having sleep apnea. As with any condition, let your healthcare provider know if you experience any new or worsened symptoms.

Depression and sleep apnea

According to a 2008 study¹⁶ from the CDC, obstructive sleep apnea’s symptoms have been found to be associated with major depression—regardless of factors like weight, age, sex, or race. The relationship between sleep and depression, however, is complex.

The obstructive episodes characteristic of OSA were found to be associated not just with feeling tired and having little energy, but also with nearly all depression symptoms, such as feeling hopeless and feeling like a failure.

The study, which surveyed 9,714 American adults, was the first nationally representative sampling of the relationship between sleep disordered breathing and depression. Of the study’s participants, 6% of men and 3% of women reported having physician-diagnosed sleep apnea. Apnea was shown to be associated with a higher prevalence of probable major depression.

The study suggests that in light of the correlation discovered between apnea and depression, further studies may be needed to determine if screening for these disorders in relation to one another should be recommended.

Screening could help identify patients who have sleep apnea and depression, which may be highly prevalent and underdiagnosed.