Sleep apnea is a common and underdiagnosed sleep disorder in which an individual's breathing repeatedly stops and starts during a night of sleep.
Symptoms include daytime sleepiness, loud snoring and restless sleep. Sleep apnea is easily diagnosed with an overnight sleep study. Untreated sleep apnea can lead to potentially serious health complications such as heart disease and depression, as well as increase the risk of motor vehicle accidents from drowsy driving.
The English medical word apnea comes from the Greek word apnoia, meaning "absence of respiration." The Greek word apnos means "without breathing;" the prefix a in Greek means "not." The Greek word pneo or pnein means "to breathe."
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Fast facts on sleep apnea
Here are some key points about sleep apnea. More detail and supporting information are in the main article.
- Around 1 in 5 adults have mild symptoms of obstructive sleep apnea (OSA), while 1 in 15 have moderate-to-severe symptoms.
- Approximately 18 million Americans have this disease, yet only 20% have been diagnosed and treated.
- Chronic sleep deprivation can lead to many health problems, including depression, diabetes, obesity, heart disease and an increase in accidents and work errors.
- Sleep apnea causes insulin resistance and, as a result, may cause or worsen diabetes.
- Menopausal and postmenopausal women have an increased risk of OSA.
- It has been estimated that one-quarter of the prevalence of OSA is due to a genetic predisposition.
- Sleep apnea is an independent risk factor for hypertension.
- Motor vehicle accidents are 2-3 times more common in individuals with sleep apnea.
- Smokers are more likely to have OSA than past or never smokers.
- While sleep apnea is more prevalent in those aged 50 and above, it can affect people of all ages, including children.
What is sleep apnea?
Sleep apnea is an involuntary pause in breathing that occurs during sleep, either from a blocked airway (obstructive) or a signaling problem in the brain (central). Approximately 90% of people with sleep apnea have OSA.
According to Medilexicon's medical dictionary, OSA is:
A disorder, first described in 1965, characterized by recurrent interruptions of breathing during sleep due to temporary obstruction of the airway by lax, excessively bulky, or malformed pharyngeal tissues (soft palate, uvula, and sometimes tonsils), with resultant hypoxemia and chronic lethargy. Sleep in the supine position predisposes apnic episodes.
People with this disorder unknowingly stop breathing repeatedly throughout nighttime sleep. Once the airway is opened or the breathing signal is received, the person may snort, take a deep breath or may awaken completely with a sensation of gasping, smothering or choking.
Causes of sleep apnea
Loud snoring typically associated with OSA is caused by air squeezing through a restricted airway.
Various factors can contribute to the blocking or collapse of the airway. When you sleep, the muscles that keep your airway open along with the tongue relax, causing the airway to narrow. Under normal conditions, this relaxation does not prevent the flow of air in and out of the lungs.
In OSA, however, the airway can become obstructed (blocked) during the natural relaxation period - particularly when there is additional thickened tissue or excessive fat stores surrounding the airway.
This blockage restricts the airflow, and any air that squeezes past can cause the loud snoring typically associated with OSA.
When the airway becomes completely blocked, the snoring stops and there is no breathing (apnea) for a 10-20 second time period or until the brain senses the apnea and signals the muscles to tighten, returning the airflow. Although this process continues hundreds of times throughout the night, the individual experiencing the apnea is not conscious of the problem.
In central sleep apnea (CSA) - the less common form of sleep apnea - the neurological controls for breathing are abnormal, causing the control and rhythm of breathing to malfunction. In most cases, CSA is associated with an underlying medical condition such as stroke or heart failure, recent ascent to high altitude or the use of pain relief medication.
Risk factors for sleep apnea include:
- Supine (flat on back) sleeping
- Chronic sinusitis
- Large neck circumference
- Recent weight gain
- Large tonsils or adenoids
- Down syndrome
- Family history of sleep apnea
- Recessed chin or large overbite.
Symptoms of sleep apnea
Episodes of apnea during sleep may be witnessed by another person. They may notice the person stop breathing, suddenly gasp or grunt, wake up for a second or two and then go back to sleep.
One of the most common symptoms of sleep apnea is daytime sleepiness. Even though the patient with OSA may not be aware of their problem, if they woke up lots of times during the night their sleep will not be a good quality restful one. Consequently, during the day they will feel unusually sleepy.
Additional signs and symptoms may include:
- Restless sleep or insomnia
- Difficulty concentrating
- Loud snoring
- Waking up several times a night to urinate
- Awakening with a dry mouth or sore throat
- Morning headache
- Decreased libido and erectile dysfunction
- Large neck circumference (greater than 17 inches for men, greater than 15 inches for women)
Sleep disorders have also been associated with a number of complications and other conditions. These include motor vehicle accidents, impaired cognition, metabolic syndrome, mood changes, hypertension, stroke, glaucoma, memory troubles, chronic fatigue, decreased quality of life and increased mortality (death).
On the next page, we look at the tests and diagnosis of sleep apnea and the available treatment options for the condition.