Central sleep apnea is a disorder in which breathing repeatedly stops and starts during sleep.

Central sleep apnea occurs because the brain doesn't send proper signals to the muscles that control breathing. This condition is different from obstructive sleep apnea, in which breathing stops because the throat muscles relax and block the airway. Central sleep apnea is less common than obstructive sleep apnea.

Central sleep apnea can result from other conditions, such as heart failure and stroke. Another possible cause is sleeping at a high altitude.

Treatments for central sleep apnea might involve managing existing conditions, using a device to assist breathing or using supplemental oxygen.

Common symptoms of central sleep apnea include:

• Observed episodes of not breathing during sleep.
• Sudden awakenings with shortness of breath.
• Not being able to stay asleep, known as insomnia.
• Excessive daytime sleepiness, known as hypersomnia.
• Trouble focusing.
• Mood changes.
• Morning headaches.
• Snoring.

Although snoring suggests some degree of a blocked airway, snoring also can occur in people with central sleep apnea. However, snoring may not be as prominent with central sleep apnea as it is with obstructive sleep apnea.

When to see a doctor

Consult a medical professional if you have — or if your partner notices — any symptoms of central sleep apnea, particularly:

• Shortness of breath that awakens you from sleep.
• Pauses in your breathing during sleep.
• Trouble staying asleep.
• Excessive daytime drowsiness, which may cause you to fall asleep while you're working, watching television or even driving.

Ask a member of your health care team about any sleep problem that leaves you regularly fatigued, sleepy and irritable. Excessive daytime drowsiness can be due to other disorders, so it's important to get an accurate diagnosis. Sleepiness during the day may be caused by obstructive sleep apnea, by not allowing yourself time to get enough sleep at night or by sudden attacks of sleep, known as narcolepsy.

Central sleep apnea occurs when your brain doesn't transmit signals to your breathing muscles.

The brainstem links the brain to the spinal cord. It controls many functions, including heart rate and breathing. Central sleep apnea can be caused by a number of conditions that affect the ability of the brainstem to control breathing.

The cause varies with the type of central sleep apnea you have. Types include:

• Cheyne-Stokes breathing. This type of central sleep apnea is most commonly associated with congestive heart failure or stroke.

  During Cheyne-Stokes breathing, breathing effort and airflow gradually rise and then lessen. During the weakest breathing effort, a total lack of airflow can occur.

• Drug-induced apnea. Taking certain medicines such as opioids can cause breathing to become irregular or stop completely for a short time. These medicines can be taken by mouth or by shot, also called injection. They include morphine (MS Contin, Mitigo, others), oxycodone (Roxicodone, Oxycontin, others) and codeine.
• High-altitude periodic breathing. A Cheyne-Stokes breathing pattern can occur if you're at a very high altitude. The change in oxygen at a high altitude can cause fast breathing, known as hyperventilation, followed by taking in too little air.
• Treatment-emergent central sleep apnea. Some people with obstructive sleep apnea develop central sleep apnea while using continuous positive airway pressure (CPAP) for treatment. This condition is known as treatment-emergent central sleep apnea. It is a combination of obstructive and central sleep apneas.
• Medical condition-induced central sleep apnea. Several medical conditions, including end-stage kidney disease and stroke, may lead to central sleep apnea. This type of sleep apnea doesn't involve Cheyne-Stokes breathing.
• Primary central sleep apnea, also known as idiopathic sleep apnea. The cause of this uncommon type of central sleep apnea is not known.

Certain factors put you at increased risk of central sleep apnea:

• Sex. Males are more likely to develop central sleep apnea than are females.
• Age. Central sleep apnea is more common among older adults, especially those older than age 60. This could be because people older than 60 are likely to have other medical conditions or sleep patterns that are linked to central sleep apnea.
• Heart disorders. Heart problems put people at higher risk of central sleep apnea. An irregular heartbeat, known as atrial fibrillation, can increase the risk. Having heart muscles that don't pump enough blood for the body's needs, known as congestive heart failure, also can raise the risk.
• Stroke, brain tumor or a structural problem with the brainstem. These brain conditions can affect the brain's ability to regulate breathing.
• High altitude. Sleeping at an altitude higher than you're used to may increase your risk of sleep apnea. High-altitude sleep apnea resolves a few weeks after returning to a lower altitude.
• Opioid use. Opioid medicines may increase the risk of central sleep apnea.

• CPAP. Some people with obstructive sleep apnea develop central sleep apnea while using continuous positive airway pressure (CPAP). This condition is known as treatment-emergent central sleep apnea. It is a combination of obstructive and central sleep apneas.

  For some people, complex sleep apnea goes away with continued use of their CPAP device. Other people may be treated with a different kind of positive airway pressure therapy.

Central sleep apnea is a serious medical condition. Some complications include:

• Fatigue. The repeated awakenings associated with sleep apnea make restorative sleep impossible. People with central sleep apnea often have severe fatigue, daytime drowsiness and irritability.

  You might have trouble focusing. You also may find yourself falling asleep at work, while watching television or even while driving.

• Cardiovascular problems. Sudden drops in blood oxygen levels that occur during central sleep apnea can affect heart health.

  If you have heart disease, repeated episodes of low blood oxygen increase the risk of irregular heart rhythms.

A primary care professional might evaluate your condition based on your symptoms. Or you may be referred to a sleep specialist in a sleep disorder center.

A sleep specialist can help you decide on your need for further evaluation. That might involve overnight monitoring of your breathing and other body functions during a sleep study called polysomnography.

During polysomnography, you're connected to equipment that monitors your heart, lung and brain activity, breathing patterns, arm and leg movements, and blood oxygen levels while you sleep. You may have a full-night or split-night sleep study.

In a split-night sleep study, you're monitored during the first half of the night. If you're diagnosed with central sleep apnea, staff might wake you to start a therapy for the second half of the night. The therapy might be positive airway pressure or supplemental oxygen.

Polysomnography can help diagnose central sleep apnea. It also can help rule out other sleep disorders, such as obstructive sleep apnea, repetitive movements during sleep or narcolepsy. These other disorders can cause excessive daytime sleepiness but require different treatment.

Doctors trained in nervous system diseases, known as neurologists, and in heart diseases, known as cardiologists, and others might be involved in evaluating your condition. You might need imaging of your head or heart to look for contributing conditions.

You're likely to start by seeing a member of your primary health care team. You might then be referred to a sleep specialist.

Here's some information to help you get ready for your appointment.

What you can do

• Bring results of prior sleep studies or other tests with you or ask that they be sent to your sleep specialist.
• Ask someone, such as a spouse or partner, who has seen you sleeping to come with you to your appointment. This person will likely be able to provide your doctor with additional information.
• Write down your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment, and when they began.
• Write down key personal information, including major stresses or recent life changes.
• Make a list of all medicines, vitamins or supplements you take, including doses.
• Write down questions to ask your health care team.

For central sleep apnea, some basic questions to ask include:

• What's the most likely cause of my symptoms?
• Are there other possible causes for my symptoms?
• What tests do I need? Do these tests require special preparation?
• Is this condition temporary or long lasting?
• What treatments are available, and which do you recommend?
• How will treating or not treating my central sleep apnea affect my health now and in the future?
• I have other health conditions. How can I best manage these conditions together?
• Are there brochures or other printed material that I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your health care team is likely to ask you a number of questions, such as:

• Have your symptoms been continuous or do they come and go?
• Can you describe your typical sleep schedule?
• How long do you sleep, and do you sleep soundly? How many times do you wake during the night?
• Do you know if you snore?
• How do you feel when you wake up? Are you short of breath?
• Do you fall asleep easily during the day?
• Has anyone ever told you that you stop breathing while you're sleeping?
• Are you short of breath when you wake up at night?
• Do you have heart problems? Have you had a stroke?