At a Glance
The cause of sleep apnea depends on the type of sleep apnea. Obstructive sleep apnea stems from conditions that physically block the airway, such as obesity, a stuffy nose, or anomalies in the shape of your face and neck. Central sleep apnea occurs when the brain fails to signal the muscles that control breathing, often as a result of medical conditions like heart failure.
Sleep apnea doesn't have a single cause. A variety of medical and lifestyle factors can interfere with normal breathing during sleep and raise the risk of sleep apnea. Some of these factors can be changed, and some can’t.
Ultimately, the underlying cause depends on the type of sleep apnea and can range from physical characteristics that narrow the airway to medical conditions that affect the body's ability to regulate breathing. Below, we’ll cover the most common causes of sleep apnea and who’s most at risk.
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Causes of Sleep Apnea
There are two main types of sleep apnea: obstructive and central. The causes depend on which type of sleep apnea you have.
Obstructive Sleep Apnea Causes
Obstructive sleep apnea (OSA) involves pauses in breathing that occur when the airway is blocked. This may be due to the tongue or other soft tissues and muscles relaxing during sleep and falling into the airway, or it may be due to structures that take up too much space, such as nasal polyps.
Technically, OSA occurs when the pressure inside the airway isn’t enough to withstand the pressure of surrounding tissues, causing collapse of the airway. During sleep, the nerves and muscles in the airway aren’t as active. Breathing naturally slows, paving the way for breathing pauses in people whose airway is naturally weaker.
The airway may collapse due to external pressure on the airway tunnel walls, such as when the neck is carrying extra fat. Narrowing the entrance to the airway due to structures like nasal polyps can also affect pressure levels inside the airway, making it more likely to collapse.
Central Sleep Apnea Causes
Whereas OSA occurs due to a physical obstruction of the airway, central sleep apnea (CSA) involves pauses in breathing due to faulty control from the brain’s respiratory center. The problem in the brain may exist during the daytime as well, but people usually remember to breathe if they’re awake.
During sleep, you can identify CSA because the person won’t try to inhale like they would with OSA. This is also why snoring isn’t as common with CSA, while it’s a hallmark symptom of OSA.
CSA is usually a result of another medical condition, such as heart failure, a central nervous system disorder, or a neuromuscular disorder. People may also experience CSA symptoms when sleeping at high altitudes or after taking opioids.
Causes of Complex Sleep Apnea
Complex sleep apnea refers to sleep apnea that displays both obstructive and central breathing pauses. Complex sleep apnea was previously called treatment-emergent sleep apnea, because this condition can occur when someone uses CPAP therapy or has a tracheotomy to treat OSA and ends up developing symptoms of CSA. Usually, these symptoms go away after a couple of months.
Risk Factors for Sleep Apnea
Risk factors for sleep apnea depend on whether the sleep apnea is obstructive or central.
Risk Factors for Obstructive Sleep Apnea
Obstructive sleep apnea is influenced by conditions that cause physical blockage of the throat. Factors that increase the possibility of OSA include:
- Obesity
- Use of alcohol or sedatives, which relax the muscles
- Menopause
- Older age
- Genetics, or a family history of sleep apnea
- High blood pressure
- Back sleeping
- Male sex
- Race (Black people, Chinese people, Mexican people, and Pacific Islanders may be more likely to have facial anatomy that triggers OSA)
There are also anatomical risk factors, including:
- Small airway
- High, arched palate
- Small lower jaw (micrognathia) or a lower jaw that’s set further back than usual
- Enlarged tonsils or adenoids (in children)
- Large tongue
- Nasal polyps or deviated septum
- Short or thick neck
Risk Factors for Central Sleep Apnea
Central sleep apnea is usually caused by a condition that directly affects the brain or heart. Causes of CSA include:
- Congestive heart failure
- Stroke
- Kidney disease
- Opioid use
- Hypothyroidism
- Damaged brain tissue
- Rare birth conditions
- Sleeping at high altitude (may occur in healthy people and disappear after return to sea level)
- Older age
- Male sex
Many other medical conditions can also contribute to CSA.
When to Talk to Your Doctor
Talk to your doctor if you’re experiencing symptoms of sleep apnea, such as:
- Regular, loud snoring
- Pauses in breathing observed by a bed partner
- Snorting, gasping, or choking during sleep
- Daytime sleepiness
- Morning headaches
- Dry mouth or sore throat
- Frequent nighttime urination (nocturia)
- Waking up feeling unrefreshed
- Trouble concentrating or remembering things
- Mood changes
- Insomnia
There are effective treatments for sleep apnea, but the longer it goes unaddressed, the higher the risk of developing health conditions such as high blood pressure, diabetes, and heart disease.
Frequently Asked Questions
A deviated septum doesn’t usually directly cause sleep apnea. However, if the deviation is significant, it could worsen obstructive sleep apnea symptoms. Seeking surgery to repair a deviated septum may not completely cure sleep apnea, but it may help CPAP therapy to be more effective.
While hypertension (high blood pressure) doesn’t directly cause sleep apnea, there’s a bidirectional relationship between the two conditions. Sleep apnea can lead to or worsen high blood pressure due to the frequent dips in blood oxygen that strain on the heart. Conversely, high blood pressure can worsen existing sleep apnea symptoms.
While there’s no strong evidence suggesting tinnitus causes sleep apnea, they do appear to be linked. Research shows that rates of tinnitus are higher in people with severe sleep apnea.
It’s most likely that sleep apnea affects the progression of tinnitus. Loud snoring and fluctuating oxygen levels due to OSA may damage the cochlea (part of the ear), leading to hearing loss that exacerbates tinnitus.
Asthma doesn’t cause sleep apnea, but it’s common for people to have both OSA and asthma. The two conditions likely influence each other, and may also be influenced by shared third factors, such as obesity, nasal polyps, or seasonal allergies.
Like sleep apnea, asthma affects breathing, and it’s possible that both conditions occur due to similar physical causes. Asthma occurs when the bronchi swell in response to a trigger, constricting the airway and making it difficult to breathe.
People with asthma are more likely to have a stuffy nose and other changes to the airway that can trigger sleep apnea. Some asthma medications may also contribute to OSA, although medications for reducing nasal congestion seem to help reduce sleep apnea symptoms.
Multiple studies show a link between post-traumatic stress disorder (PTSD) and obstructive sleep apnea, and experts believe each condition influences the other.
OSA affects sleep quality, making it more likely that a person will experience bad nightmares — a key component of PTSD. On the flip side, PTSD keeps the fight-or-flight system activated, causing the sleeper to sleep less deeply and leaving them more vulnerable to waking up from lapses in breathing. Antidepressants prescribed for PTSD may interfere with sleep as well.
Research suggests that having OSA may make it more likely for a person to develop PTSD after a traumatic event. OSA also interferes with PTSD healing methods like exposure therapy. Treating OSA tends to improve PTSD, although people with PTSD may be more likely to experience CPAP side effects, such as claustrophobia from wearing a mask that reminds them of active combat.
Short-term stress isn’t considered a direct trigger for sleep apnea, although emerging research suggests that stress may play a role in OSA. Notably, stress interferes with sound sleep, which could exacerbate symptoms of existing sleep apnea. Additionally, stress often goes hand-in-hand with unhealthy behaviors like drinking alcohol and getting insufficient exercise, which are risk factors for OSA.
Long-term stress may cause chronic inflammation in the body that could eventually increase the risk of developing sleep apnea.
Allergies to pollen, pet dander, and dust mites are a known trigger for sleep apnea, as they can cause a stuffy nose that directly narrows the entrance to the airway. Minimizing exposure allergens and treating allergies with over-the-counter medications, nasal sprays, or personalized treatments recommended by your doctor can help reduce sleep apnea symptoms during allergy season.
Anxiety isn’t generally considered one of the main causes of sleep apnea, although it may contribute to sleep problems that heighten sleep apnea symptoms. For its part, OSA may contribute to stress, anxiety, and depression by causing dips in blood oxygen levels that affect brain function over time.
Written by
Danielle Pacheco, Contributing WriterDanielle is originally from Vancouver, BC, where she has spent many hours staring at her ceiling trying to fall asleep. She channels her frustration into researching sleep solutions and sharing insights with fellow insomniacs. Danielle spends her downtime trying out new recipes and working off the calories on the soccer field. Danielle studied the science of sleep with a degree in psychology at the University of British Columbia.
