Sleep Apnea

How sleep apnea works

During sleep, the muscles that hold the throat open relax. In obstructive sleep apnea (OSA), the soft palate, tongue and throat walls collapse inward, partly or completely blocking airflow even though the chest keeps trying to breathe. Oxygen falls, carbon dioxide rises, and the brain briefly wakes the body (often with a snort or gasp) to reopen the airway. This cycle repeats all night, fragmenting sleep.

In central sleep apnea (CSA), there is no blockage. The brain's breathing control center temporarily stops sending signals, so there is no effort to breathe. A pattern called Cheyne-Stokes breathing, with breaths waxing and waning, is typical in heart failure.

Types of sleep apnea

Treatment-emergent (complex) central apnea appears in some people when CPAP is started for OSA and often settles with continued use.

Causes and risk factors

Obstructive sleep apnea

• Excess weight, especially around the neck. Obesity is the strongest modifiable risk factor
• Male sex, and women after menopause
• Older age
• Airway anatomy: large tonsils, a small or recessed jaw, a large tongue, a narrow palate
• Nasal blockage: deviated septum, allergies
• Alcohol, sedatives and sleeping pills
• Smoking
• Family history
• Medical conditions: hypothyroidism, acromegaly, Down syndrome, polycystic ovary syndrome
• Children: enlarged adenoids and tonsils

Central sleep apnea

• Heart failure and atrial fibrillation
• Stroke and other brainstem conditions
• Opioid medicines
• High altitude
• Kidney failure

Symptoms

Loud snoring, witnessed pauses, gasping, unrefreshing sleep, daytime sleepiness, morning headaches, night-time urination, poor concentration and irritability. See sleep apnea symptoms for a full checklist, symptoms in women and children, and a screening questionnaire.

Diagnosis and severity

A home sleep apnea test is appropriate for many adults with likely moderate to severe OSA and no major heart or lung disease. In-lab polysomnography is used for children, suspected central apnea, other sleep disorders, or when a home test is negative but suspicion remains.

Severity in adults is based on the apnea-hypopnea index (AHI), the average number of pauses and shallow breaths per hour of sleep:

In children, an AHI above 1 is abnormal. Oxygen levels, symptoms and other health problems are considered alongside the AHI.

Health risks of untreated sleep apnea

• High blood pressure, including resistant hypertension that needs several medicines. See hypertension
• Atrial fibrillation and other heart rhythm problems
• Heart failure, coronary disease and stroke
• Type 2 diabetes and insulin resistance
• Fatty liver disease
• Depression and cognitive problems
• Road traffic and workplace accidents from sleepiness
• Complications during surgery and anesthesia
• Pregnancy complications such as preeclampsia and gestational diabetes

Treatment

Positive airway pressure (CPAP)

Continuous positive airway pressure blows air through a mask to splint the throat open. It is the most effective treatment for moderate to severe OSA, reducing sleepiness, improving blood pressure and quality of life. Auto-adjusting machines (APAP) vary the pressure through the night. Benefits depend on regular use, ideally all night, every night. Mask fitting, humidification, and a few weeks of practice solve most early problems.

Oral appliances

A custom mandibular advancement device made by a dentist holds the lower jaw forward. It suits mild to moderate OSA and people who cannot use CPAP.

Weight loss

Losing weight reduces severity and can cure mild OSA. Lifestyle programs, prescription weight-loss medicines and bariatric surgery are all options. In 2024, the FDA approved tirzepatide for moderate to severe OSA in adults with obesity.

Positional therapy

For OSA that occurs mainly on the back, devices or simple measures that keep you on your side help.

Hypoglossal nerve stimulation

An implanted device stimulates the nerve to the tongue with each breath, keeping the airway open. It is an option for some people with moderate to severe OSA who cannot use CPAP and meet weight and anatomy criteria.

Surgery

• Tonsil and adenoid removal is the first-line treatment for most children with OSA.
• In adults, procedures on the palate, nose or jaw are used in selected cases. Maxillomandibular advancement (moving both jaws forward) is highly effective but a major operation.

Treating central sleep apnea

Optimize treatment of heart failure, reduce or stop opioids if possible, and use CPAP, bilevel or adaptive servo-ventilation (ASV). ASV is not recommended in people with heart failure and a significantly reduced ejection fraction. Implanted phrenic nerve stimulation is another option for some.

Lifestyle steps

Avoid alcohol in the evening, stop smoking, review sedative medicines, treat nasal congestion and keep a regular sleep schedule.

Outlook

Sleep apnea is a long-term condition, but treatment works. Most people using CPAP regularly feel more alert within days to weeks. Blood pressure and quality of life improve, and the risk of accidents falls. Regular follow-up checks symptoms, equipment and weight.

Frequently asked questions

What is the difference between obstructive and central sleep apnea?

In obstructive sleep apnea, the throat physically collapses during sleep while the body keeps trying to breathe. In central sleep apnea, the brain temporarily stops signaling the breathing muscles, so there is no effort. Obstructive is far more common. Central is linked to heart failure, stroke and opioids.

What causes sleep apnea?

Obstructive sleep apnea is mainly caused by excess weight, a narrow or crowded airway, older age, male sex, alcohol and sedatives. In children, large tonsils and adenoids are the usual cause. Central sleep apnea is caused by heart failure, stroke, opioid medicines and high altitude.

What is the best treatment for sleep apnea?

CPAP is the most effective treatment for moderate to severe obstructive sleep apnea. Oral appliances suit mild to moderate cases. Weight loss, positional therapy, nerve stimulation implants and surgery are other options. Removing tonsils and adenoids treats most children.

Can sleep apnea be cured?

Sometimes. Children often improve fully after tonsil and adenoid removal, and significant weight loss can resolve obstructive sleep apnea in some adults. For most adults it is a long-term condition that is well controlled with treatment.

Can sleep apnea kill you?

Untreated severe sleep apnea increases the risk of heart attack, stroke, heart rhythm problems and fatal car crashes, and is linked with higher overall mortality. People rarely die directly from a breathing pause. Effective treatment lowers these risks.