What Causes Sleep Apnea?

Written by Nicole Schmidt
Medically Reviewed by Zilpah Sheikh, MD on July 10, 2025
10 min read

The causes of sleep apnea include age, excess weight, certain health conditions, specific medications, and even your body structure. It may also result from smoking, drinking alcohol, hormonal or neurological problems, or daily habits that affect how you breathe while you sleep.

The causes may be different, but the result is the same. Your breathing stops or slows to the point where your body doesn’t get enough oxygen. You often wake up and miss out on deep, restful sleep.

Sleep apnea is common. It can be a serious health problem. Each time you stop breathing, it lasts at least 10 seconds. Sometimes, it lasts a minute or more. This can happen five or more times every hour. In severe cases, you may stop breathing over 30 times an hour.

There are three types of sleep apnea. You might have:

Obstructive sleep apnea (OSA). This happens when your throat muscles relax during sleep. They press on your airway and block your breathing.

Central sleep apnea (CSA). This occurs when your brain fails to send the correct signals to your breathing muscles during sleep. It is like your body forgets to breathe.

Mixed or complex sleep apnea. This is a mix of both obstructive and central sleep apnea. You may have blocked airways and missed signals from your brain at the same time.

In adults, the most common reason for obstructive sleep apnea is being overweight or having obesity. 

Extra weight, especially around the neck, can lead to more soft tissue in the mouth and throat. During sleep, this tissue can block the airway and make it harder to breathe.

More than half of the people with obstructive sleep apnea are either overweight (body mass index, or BMI, of 25-29.9) or have obesity (BMI of 30.0 or above). Gaining 10% more body weight increases your chances of having OSA by six times. 

The size of your neck can also be a sign of obesity. If you’re a man with a neck size over 17 inches (43 centimeters) or a woman with a neck size over 15 inches (38 centimeters), you’re much more likely to have OSA.

“If someone can remember a weight at which they didn’t snore, then they gained weight, started snoring a lot and were diagnosed with sleep apnea, there’s a good chance that getting back to their previous size may cure their sleep apnea,” says Matthew Ebben, MD, a sleep medicine specialist and associate professor at Weill Cornell Medicine in New York City. 

Other possible causes or risk factors for OSA include:

  • A narrow throat
  • A round head
  • Hypothyroidism
  • Excess growth due to hormones (acromegaly)
  • Allergies
  • Deviated septum (problem with nose structure)
  • Medical conditions that congest the upper airways
  • Smoking
  • Alcohol or drug abuse

In children, OSA can have a range of causes, including: 

  • Enlarged tonsils or adenoids, which can block airflow during sleep
  • Dental issues, such as a large overbite 
  • Down syndrome, which can cause an enlarged tongue, adenoids, and tonsils, along with weaker upper airway muscles 
  • Pierre-Robin syndrome, where a small lower jaw can cause the tongue to ball up and fall to the back of the throat
  • Tumors or growths inside the airway (though these are less common)

Why understanding the causes matters

No matter your age, untreated obstructive sleep apnea can lead to serious problems, such as cardiovascular disease, accidents, and even early death.

When you know what causes your sleep apnea and how serious it is, your doctor can choose the best treatment. You might use a breathing device, such as a continuous positive airway pressure (CPAP) machine, while you sleep. Your doctor may also treat health conditions that worsen your sleep apnea. In some cases, you may need surgery.

“Sleep apnea is underdiagnosed, so people who think they might have it should get it checked out,” says Ebben. That includes those who snore loudly, wake up several times at night, and feel tired during the day. 

“People who are treated for it often feel more alert and refreshed during the day. What’s better than that?”

In many cases, doctors can’t find the exact cause of CSA. They call this primary, or “idiopathic,” CSA.

But CSA can sometimes be linked to other illnesses, medications, or environmental factors, including:

Stroke, heart failure, or kidney failure. These conditions can cause CSA with a type of breathing called Cheyne-Stokes respiration, where you breathe fast and shallow, then slow and deep, followed by a short pause with no breathing at all. Doctors call this pattern CSB-CSA.

Heart conditions, kidney problems, and other illnesses. These conditions can also cause non-CSB-CSA.

High altitude. CSA typically happens during sleep when you’re very high up (above 8,000 feet). It usually goes away when you return to lower altitudes.

Some medications and drugs. Some medicines, such as hydrocodone, fentanyl, and others, can cause CSA. Your doctor may help you adjust your medicine. If you think you’re misusing any medication — especially opiates — talk to your doctor or a therapist.

In children, the reason for CSA is typically idiopathic, meaning the cause is unknown.

Still, several things can interfere with the brain signals that normally help your child breathe, which may lead to CSA. These include:

  • Premature birth
  • Smoking during pregnancy
  • Brain tumors
  • Cerebral palsy
  • Head injury
  • Problems at the base of the skull, or brain stem

Certain physical features — especially in and around your mouth and throat — can make it harder for air to flow freely into your lungs during sleep. In some people, this can lead to obstructive sleep apnea. 

These features may include:

  • Large tonsils or adenoids, which can block the airway, especially in children. These glands sit behind your nose and help filter out germs.
  • A narrow throat
  • A thick neck or a large tongue
  • A short lower jawline
  • A deviated septum (when the inside of your nose is off center), which can make it hard to breathe
  • A narrow, high-arched palate (roof of the mouth)

Your daily habits and routines can play a role in whether you get sleep apnea. If you already have sleep apnea, these habits can also affect how bad your symptoms get.

Many of these habits are simple to change and may help you feel better without needing more treatment.

Some of the most common lifestyle-related reasons for sleep apnea include: 

Being overweight. Carrying extra weight, especially around your neck and upper belly, can put extra pressure on your throat and lungs. This makes your airway more likely to collapse while you sleep. 

Drinking alcohol or using sedatives or tranquilizers. These substances relax the muscles in your throat, which can block your airway and worsen your sleep apnea symptoms.

Not exercising. Regular physical activity helps lessen fluid buildup in your body, easing pressure on your airways while you sleep. Research shows that even exercise that doesn’t result in weight loss can improve symptoms of sleep apnea.

Smoking. It causes inflammation and fluid retention in the upper airway, which can make it harder to breathe at night. It’s estimated that smokers are three times more likely to have obstructive sleep apnea than those who have never smoked.

Normally, the muscles in your throat, including your tongue, hold your airway open while you sleep. But during the deeper stages of sleep, those muscles relax. For some people, this causes the soft tissue in the throat to sag or collapse inward.

In obstructive sleep apnea, the muscles may be too weak or slow to respond, so they don’t tighten quickly or strongly enough to reopen the airway once it starts to close.

With central sleep apnea, the problem starts in the brain. It doesn’t signal your breathing muscles properly, so your body may simply forget to breathe for a few seconds. This has been linked to certain neurological disorders, including:

Stroke. If a stroke damages the parts of the brain that control breathing, it can affect your breathing patterns during sleep. Central sleep apnea happens in about 6%-24% of people who have had a stroke, while obstructive sleep apnea happens in as many as 70%. In some cases, symptoms may improve over time.

Neurodegenerative conditions, such as Parkinson’s or amyotrophic lateral sclerosis (ALS). Up to 40% of people with Parkinson’s also have sleep apnea — although the link between the two isn’t fully understood. In people with ALS, sleep apnea often develops because the disease weakens and damages muscles that control breathing over time.

Some psychiatric disorders, such as major depressive disorder or posttraumatic stress disorder (PTSD). There’s growing evidence that suggests sleep apnea is more common in people with major depressive disorder or PTSD, but more research is needed to understand the link.

Some health conditions — especially ones that affect your hormones — can cause fluid to build up in your body or lead to weight gain, which can make sleep apnea more likely. These conditions include:

Hypothyroidism (underactive thyroid). If your body doesn’t make enough thyroid hormone, it can cause symptoms such as weight gain or swelling in the tissue near the airway — both of which may contribute to sleep apnea.

Polycystic ovary syndrome (PCOS). People with PCOS often have higher levels of androgens (male sex hormones). This hormonal imbalance can lead to weight gain. About 20% of people with PCOS also have obstructive sleep apnea.

Type 2 diabetes. Research shows a link between diabetes and sleep apnea. Sleep apnea can lower oxygen levels during the night, which may lead to insulin resistance. Both conditions are also linked to obesity.

Congestive heart failure. This condition can affect how your brain controls breathing and may cause fluid to build up in your neck when you lie down. Many people with heart failure have central sleep apnea, often with a Cheyne-Stokes breathing pattern.

Sleep apnea can affect anyone, but certain factors can raise your risk, including:

Age. Sleep apnea tends to show up more often in older people, especially those over 60. This could be because as you age, you’re more likely to have other health issues linked to obstructive sleep apnea.

Sex. Males are two to three times more likely than females to get sleep apnea, and they often experience it earlier in life. For women, sleep apnea is more common after menopause or in those who are overweight.

Family history. Sleep apnea is hereditary in some cases. You might inherit physical features such as a smaller lower jaw or a thicker neck, which can make it harder to keep your airway open during sleep. Genetics that influence your weight may also play a role. About 25%-40% of people with obstructive sleep apnea have family members with the condition.

Some cases of sleep apnea are temporary and may only happen in certain conditions or environments.

When you sleep at higher altitudes (for some people, above 8,000 feet), the lower oxygen levels can disrupt your body’s normal breathing rhythm. For most people, breathing returns to normal when they get back to a lower altitude. 

Certain sleeping positions can also put extra pressure on your airways. “Some folks only have sleep apnea when they sleep on their backs, but not on their sides,” Ebben says. A high-quality sleep study can show how your habits affect your symptoms. For some people, switching positions at night helps ease sleep apnea.

About 4%-9% of middle-aged adults have obstructive sleep apnea, but many people don’t know they have it. If you’re over 65, your risk goes up — at least 10% of older adults have the condition. As you get older, your brain may not keep your throat muscles firm enough during sleep. This makes your airway more likely to narrow or collapse.

If you’re a postmenopausal woman, using hormone replacement therapy may lower your risk. Experts think estrogen or progesterone might help protect your airway. Still, doctors don’t recommend hormone therapy to treat sleep apnea, as it can affect your health in other ways.

There is increasing evidence that links sleep apnea to a wide range of other health conditions, including:

  • High blood pressure (hypertension)
  • Stroke 
  • Heart attack
  • Diabetes
  • Gastroesophageal reflux disease
  • Nocturnal angina 
  • Heart failure
  • Hypothyroidism
  • Abnormal heart rhythm

Sleep apnea can make you extremely sleepy during the day, which raises your risk for motor vehicle accidents and may play a role in depression.

Some of these complications may happen because your body releases stress hormones. These hormones respond to low oxygen levels and poor sleep. They can raise your heart rate and put extra strain on your heart and blood vessels. This may raise your risk for heart disease. But you have treatment options that can help you manage it. These include:

For central sleep apnea, doctors will also treat any underlying medical conditions that might be contributing to it.

Sleep apnea is a common sleep disorder. It causes you to stop breathing for short periods during the night. Obstructive sleep apnea happens when something blocks your airway. Central sleep apnea happens when your brain doesn’t send the right signals to control your breathing. Sleep apnea can affect both children and adults. Without treatment, it can lead to serious health problems. If you think you have it, talk to your doctor. They can find the cause and suggest the right treatment for you.

Is it okay to live with sleep apnea?

Sleep apnea can affect your quality of life. Over time, it can also lead to more serious health problems. Your doctor can help you find ways to manage your symptoms and prevent complications.

What are the warning signs of sleep apnea?

At night, sleep apnea may cause you to snore, wake up often, gasp for air, or stop breathing while you sleep. During the day, you might feel tired, have headaches, or notice changes in your mood. 

What is the first stage of sleep apnea?

Snoring is usually the first stage of sleep apnea. It’s often harmless but can develop into sleep apnea in the future.

How common is obstructive sleep apnea?

About 30 million adults in the U.S. have obstructive sleep apnea (roughly 1 in every 15 people). Central sleep apnea is less common and affects fewer than 1% of adults.