Sleep Apnea: Symptoms, Causes, and Treatments

• Sleep apnea causes breathing to repeatedly stop and restart during sleep. These pauses can last ten seconds or longer and can happen many times throughout the night.
• Pauses in breathing cause fragmented sleep and can lower blood oxygen levels, often leading to daytime sleepiness.
• Loud snoring, gasping, and breathing pauses are the most common signs of sleep apnea, and a sleeping partner often notices them first. If you experience any of these signs, consult a healthcare provider.

Sleep apnea is a common sleep disorder in which breathing repeatedly stops and restarts through the night. This pattern interferes with periods of deep sleep and overall sleep quality , leading to lower oxygen levels. This is why sleep apnea is linked not just to daytime fatigue but also to chronic conditions like high blood pressure and heart disease.

If you or a loved one snore or gasp for air while sleeping, continue reading. This guide details the common signs of sleep apnea, how the condition is diagnosed, and what treatment may look like.

Sleep apnea is a medical condition where someone's breathing stops and restarts while they are asleep. These pauses last ten seconds or more before breathing resumes, and they can disrupt deep sleep , impacting sleep quality which can lead to adverse health conditions, which we'll discuss below.

Sleep apnea is a relatively common condition, with a 2025 review of existing research estimating that somewhere between 9-38% of people worldwide have it, depending on the study and diagnostic criteria used.

There are three types of sleep apnea: obstructive, central, and complex.

Obstructive Sleep Apnea

The most common type is obstructive sleep apnea (OSA). This type occurs when the upper airway is blocked. Airflow blockages lead to either full or partial discontinuation of airflow.

Without airflow, someone may wake up throughout the night gasping for air and their blood oxygen levels may become desaturated, meaning there isn't enough oxygen in the blood to maintain normal bodily functions. When those with OSA wake up grasping for air it is the body's way of signaling desaturation. Of note, obesity, particularly an enlarged neck circumference, is the most common risk factor for OSA.

Central Sleep Apnea

The second most common type is central sleep apnea (CSA), which is when someone experiences disrupted breathing because the brain is not sending the correct signals to muscles that control breathing, such as the diaphragm, while sleeping. It's commonly associated with high altitude, heart failure , and stroke .

Complex Sleep Apnea Syndrome

If someone has both central and obstructive sleep apnea, it's referred to as complex sleep apnea syndrome or treatment-emergent central sleep apnea. About 10% of people with sleep apnea have this type.

All sleep apnea types have a similar range of symptoms, but treatment for each may differ. The American Thoracic Society outlines common symptoms when someone is asleep and awake. If you experience one or more of the following symptoms, please see a healthcare provider.

Possible Symptoms When Asleep

• Loud snoring that may wake up sleeping partners
• Gasping for air
• Choking sounds
• Trouble staying asleep or waking often during sleep
• Breathing pauses
• Jerky body movements
• Night sweats

Possible Symptoms When Awake

• Excessive daytime sleepiness
• Morning headaches
• Feeling tired, even after sleeping seven to nine hours
• Mood changes
• Dry mouth when waking up
• Trouble paying attention
• Sore throat upon waking

Warning Signs

According to the National Heart, Lung, and Blood Institute, the most common early signs include daytime sleepiness, breathing that stops and starts during sleep, and gasping for air. The exact warning signs of sleep apnea also differ by gender. Men are more likely to experience loud snoring. Insomnia, fatigue, and morning headaches are more common in women.

To prevent complications and find relief from the other symptoms above, it's important to alert healthcare professionals if experiencing any warning signs.

Long-Term Health Risks

When left untreated, sleep apnea can lead to sleepiness and low oxygen levels when sleeping. These effects are associated with a higher risk for serious health problems, including:

The cause depends on the sleep apnea type:

• Obstructive sleep apnea: A structural change in the upper airways disrupts air pressure and flow.
• Central sleep apnea: The brain doesn't produce the right signals to tell the muscles that control breathing, such as the diaphragm, to work when asleep.
• Complex sleep apnea syndrome: A mix of both causes is present.

Risk factors vary by sleep apnea type. A sleep medicine specialist will examine a patient's medical history and look for these factors during an initial evaluation.

Risk Factors for Obstructive Sleep Apnea

Many factors contribute to OSA, such as:

• Age: As we get older, soft tissue can build up in the neck or tongue, increasing the risk of OSA.
• Obesity: People with obesity have more fat around the neck, which may lead to structural changes in the upper airways.
• Large neck, tongue, or tonsils: This increases the chance of a narrow upper airway or for the tongue to block airflow when someone is asleep. If the soft palate, the soft tissue at the back of the roof of the mouth, is too large, it may also lead to OSA.
• Hormonal health conditions: People with certain hormonal conditions, such as thyroid disorders and polyendocrine metabolic ovarian syndrome (PMOS; previously known as PCOS) have a higher risk for OSA.
• Lifestyle: Heavy drinking, a sedentary lifestyle , and smoking all raise the risk of OSA.
• Chronic nasal congestion: People with stuffy noses, such as those with severe allergies , are more likely to develop OSA. However, congestion may cause sleep disturbances that appear similar to sleep apnea, making it difficult to differentiate between the two conditions.
• Gender: Men are more likely to develop OSA, though the risk increases for women after they reach menopause . The reasons for these gender differences are not fully understood, but anatomy, like larger upper bodies and neck circumference, and hormonal differences play a major role.

Some of the above risk factors are modifiable. Additionally, a healthy lifestyle may help prevent mild sleep apnea from turning into more severe OSA.

Risk Factors for Central Sleep Apnea

Central sleep apnea (CSA) shares some risk factors with OSA. Lifestyle habits, particularly smoking and heavy drinking, are associated with a higher CSA risk. Someone's risk also increases with age, and CSA is more common in men than women.

This type of sleep apnea has some unique risk factors as well:

• Family history of CSA: There appears to be a genetic component to this condition.
• Opioid use: This medication class may interfere with some brain functions related to breathing.
• Health conditions: Some conditions impact how the brain controls breathing. These include heart failure, stroke, amyotrophic lateral sclerosis, and myasthenia gravis.
• Premature birth: Those born before 37 weeks of pregnancy have a higher chance of CSA.

If you or a person sleeping near you recognize symptoms of sleep apnea, that is not enough for an official diagnosis . Instead, a healthcare provider who specializes in internal medicine or primary care must assess symptoms, risk factors, and family history. From there, the path to diagnosis often looks like this:

• If a healthcare provider suspects sleep apnea, they'll refer you to a sleep specialist for a more thorough evaluation.
• Either a specialist or a primary care provider can refer you to a sleep lab for an overnight sleep study.
• Or, they may instead recommend an at-home sleep test.

What Tests Diagnose Sleep Apnea?

There are a few different sleep apnea tests. The gold standard is polysomnography (PSG) , which is a test that takes place in a sleep center. It assesses multiple metrics associated with sleep quality and may be used to diagnose sleep apnea as well as other sleep disorders.

Metrics assessed by a PSG include:

• Air flow as someone breathes in and out
• Regular or irregular heartbeats
• Sleeping position
• Blood oxygen levels
• Brain waves
• Eye movement
• Heart rate
• Muscle activity

If you are uncomfortable sleeping outside of your home or a healthcare provider doesn't suspect other sleep disorders, they may recommend an at-home sleep test. Some of these are as effective at detecting sleep apnea as a PSG, but they are used only to diagnose sleep and cannot detect alternative sleep conditions. Even more, they do not differentiate between sleep apnea types such as OSA versus CSA.

Sleep Apnea Severity

When diagnosing sleep apnea, a healthcare provider will use sleep test results to determine the severity. They typically define severity using the apnea-hypopnea index (AHI), which measures how many breathing events occur per hour during sleep.

An apnea is when someone stops breathing for ten or more seconds due to full airway blockages. A hypopnea is when the airway is partially blocked for ten or more seconds.

The AHI ranges are:

• 0 to 5 an hour: Normal breathing
• 5 to 15 an hour: Mild sleep apnea
• 15 to 30 an hour: Moderate sleep apnea
• 30 or more an hour: Severe sleep apnea

While the AHI is important, it's one metric that informs a sleep specialist's diagnosis, not a standalone indicator of sleep apnea severity.

Once a healthcare provider diagnoses sleep apnea, they will create a treatment plan. This plan varies from patient to patient, though there are some common treatments that may be effective.

Continuous Positive Airway Pressure (CPAP) Therapy

When someone has a breathing-related sleep disorder, such as sleep apnea, their healthcare provider may prescribe CPAP therapy . A CPAP machine delivers mild air pressure to keep airways open when sleeping. The machine is connected to a mask that someone wears around their nose and possibly their mouth when sleeping. CPAP is highly effective, but getting used to it takes time; roughly 15% to 35% of people struggle with it at first. If the mask is uncomfortable, tell your provider. Adjusting the mask fit, pressure ramp, or humidifier setting often makes a difference.

Other Positive Airway Pressure (PAP) Therapies

CPAP therapy is the most common type, but there are other PAP therapies :

• Bilevel positive airway pressure (BiPAP or BIPAP): Delivers a higher pressure when someone breathes in and lower when they breathe out. This is usually prescribed for central sleep apnea.
• Autotitrating (adjustable) positive airway pressure (APAP): Changes air pressure based on breathing patterns throughout the night.

Lifestyle Changes

As either a standalone treatment for mild OSA or as an additional treatment for more severe cases, a healthcare provider may recommend lifestyle changes :

• Limit alcohol or caffeine intake
• Lose weight
• Quit smoking
• Eat a nutritious diet
• Exercise more often or increase activity time, such as walking more or taking the stairs instead of the elevator
• Sleep on your side rather than your back, which can reduce airway collapse (known as positional therapy).

Other Treatment Options

While PAP therapy and lifestyle changes are the most common treatments, other emerging treatments exist. For example, the FDA recently approved a medication for adults with moderate-to-severe obstructive sleep apnea who also have obesity.

Oral appliances, such as tongue-retaining devices and mandibular repositioning mouthpieces, may also help keep the airway open when sleeping.

What happens if sleep apnea is left untreated?

If sleep apnea remains untreated, it can greatly impact someone's overall quality of life due to daytime sleepiness and low oxygen levels when sleeping. It may increase the risk of certain medical conditions, such as high blood pressure, GERD, heart disease, and more.

What is the best position to sleep in with sleep apnea?

Side sleeping is often thought to be the best sleep position for people with sleep apnea. However, someone's sleeping position alone isn't enough to treat this condition. If you suspect that you or a loved one has sleep apnea, consider seeing a healthcare provider.

What organ does sleep apnea affect?

Sleep apnea doesn't affect one organ. It impacts many. Obstructive sleep apnea is primarily due to issues in the upper airway, like the nose, mouth, and throat. Meanwhile, central sleep apnea stems from different signaling patterns in the brain. If left untreated, sleep apnea may impact other organs too, such as the heart, liver, pancreas, or kidneys.