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What Causes Sleep Apnea?

Types of sleep apnea and their causes.

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Dayton Respiratory Center

Feb 18 2022

5 mins read

Do you wake up in the morning feeling sleepy and tired, as if you haven't slept all night? The reason could be lack of sleep.

Sleep apnea is characterized by interrupted sleep. It occurs when you intermittently stop and start breathing while you are asleep. It causes loud snoring and makes you feel drowsy during the day. You may also experience headaches, tiredness and irritability even after a full night's sleep.

More than 100 million people around the world suffer from sleep apnea. It occurs due to a disruption in the normal breathing cycle during your sleep. This disruption hinders the oxygen supply. The decreased oxygen concentration in the blood signals the brain to wake you up. Since this awakening is rapid, you are not aware of it.

Sleep Apnea

Types of Sleep Apnea

  • Obstructive sleep apnea (OSA) is a prevalent sleep disorder. It occurs when the soft tissues in your throat relax and obstruct the airways during sleep, cutting off the air supply. As a result, the oxygen level dips. The brain senses this oxygen deficiency and sends a signal to awaken you. You start breathing with a loud gasp or jerk, interrupting your sleep.
  • Central sleep apnea(CSA) occurs when your brain fails to signal the muscles that aid breathing. Consequently, you intermittently stop breathing during sleep. CSA can develop due to a problem in the brainstem (area of the brain that controls breathing). 
  • Complex sleep apnea, sometimes called treatment-emergent sleep apnea, occurs when you suffer from obstructive and central sleep apnea. 

What Causes Sleep Apnea?

The cause or reason for interrupted sleep depends on its type. Let’s look into the cause of each type in detail.

Obstructive Sleep Apnea

Obesity and excess weight are the two main reasons for OSA. When the tongue and soft tissues at the back of your throat relax and fall back during sleep, they narrow and block the airways. 

Obese and overweight people are more prone to OSA. The excess fat deposit narrows their airways. During sleep, the muscles relax, thereby blocking the narrow airways. A weight gain of 10% increases your chances of OSA by six times.

Other causes of OSA are:

  • A narrow throat. The respiratory tract in some people is inherently narrow. The narrow airways interfere with normal breathing and lead to sleep apnea.
  • An enlarged tonsil
  • Hypothyroidism. Low levels of thyroid hormone cause hypothyroidism. The thyroid hormone regulates brain functions, and its abnormal levels affect the brain, nerves and muscles involved in respiration.
  • Allergies cause nasal congestion, blocking your airways and interfering with sleep.
  • GERD (Gastroesophageal reflux disease). In this condition, acid backflow into the esophagus occurs when the lower esophageal sphincter remains open. This reflux causes your throat muscles to contract and leads to obstructive sleep apnea.
  • Smoking/ Alcohol/ Drug use. Smoking exacerbates inflammation causing fluid retention, which leads to restricted airways. Alcohol and drugs relax the muscles aggravating the symptoms of obstructive sleep apnea.
  • Acromegaly is a hormone disorder characterized by high levels of growth hormones. It is associated with enlargement of facial bones, increase in tongue size and swelling of the throat. These factors contribute to sleep apnea. 
  • Deviated septum. If your septum is curved or deviated, one nasal airway can be narrower than the other. The constricted airway can interfere with normal breathing.

Central Sleep Apnea

Central sleep apnea can develop due to a medical condition or be idiopathic (unknown cause).

The following conditions cause CSA:

  • Cheyne-Stokes breathing is an irregular breathing pattern. In this condition, your breathing gradually deepens and becomes faster. It then slows down, resulting in a momentary pause called apnea. A chronic heart failure or stroke gives rise to this type of central sleep apnea.
  • Health problems. Heart failure, stroke, kidney failure, and diabetes are some medical conditions that can increase sleep deprivation.
  • Medications such as opioids can affect your breathing patterns. Your breathing may increase, decrease or even stop temporarily.
  • Other treatments. Central sleep apnea can develop while treating obstructive sleep apnea using  CPAP (continuous positive airway pressure).
  • High-altitude. Oxygen deficient air at high altitudes can cause a Cheyne-Stokes breathing pattern. It is temporary and normal breathing resumes at lower altitudes.

Complex Sleep Apnea

Complex sleep apnea sometimes develops in patients undergoing CPAP treatment. CPAP (continuous positive airway pressure) treatment is the most common therapy for obstructive sleep apnea. This therapy delivers a steady positive air pressure that keeps the airways open and aids breathing. However, these patients experience central sleep apnea during the treatment.

Patients may also develop complex sleep apnea after a tracheostomy surgery. Tracheostomy is a therapy used to treat obstructive sleep apnea. Some patients develop central sleep apnea soon after this surgery.


Talk to your doctor if you experience drowsiness and tiredness or have a problem falling asleep. If untreated, sleep apnea will not only make you sleep deprived but can also lead to other complications. Good sleep ensures a healthy mind and body.

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