Apnea is suspension or cessation or a pause in breathing. Since it occurs while you are asleep it is called sleep apnea. Sleep apnea causes and risk factors that make you prone to suffer from both OSA and CSA in men and women are explored.

Obstructive sleep apnea (OSA) occurs due to the blockage or obstruction of the airway, which can be due to several reasons. In such cases, breathing becomes laborious and you snore loudly.

Central sleep apnea (CSA) occurs because the brain fails to send signals to the respiratory muscles to function and bring about respiration. This type of sleep apnea is rare.

You should never ignore this condition because it can cause serious health complications. Therefore, once the diagnostic evaluation is complete, your doctor has effective treatment options. Certain cases of OSA may require surgical treatment. Your sleep doctor will also advise lifestyle improvements and home remedies that will improve your symptoms.

In normal circumstances, the muscles of the throat around the windpipe keep the airway stiff and open to facilitate proper breathing (entry and exit of air).

When you sleep, these throat muscles are in a more relaxed state but they still keep the windpipe open allowing you to breathe normally.

These muscles support the soft palate, the uvula, the tonsils, and the tongue. In obstructive apnea, this muscle support fails due to certain reasons and is the main cause of sleep apnea.

Secondly, due to less intake of oxygen because of restricted breathing, oxygen levels in the blood fall.

When this fall is excessive, the brain wakes you up because when you awaken, the throat muscles tighten and the airway is opened allowing you to breathe in freely and increase oxygen levels in the blood.

This happens repetitively during the night with a choking sound and deprives you of deep sleep. These frequent drops in oxygen levels cause the release of stress hormones, which can cause blood pressure and heart complications.

Obstructive Sleep Apnea (OSA)

Persons with obstructive sleep apnea (OSA) often have a low muscle tone and the airway is often narrower than normal. It may get repetitively blocked or narrowed during sleep due to the following reasons and risk factors. It is typically identified by its symptoms, of which loud snoring is the most common.

OSA risks 

  • Males: Males are three times more prone to develop obstructive apnea.
  • Menopause: In women, risk increases after menopause.
  • Ethnicity: It is seen more in Blacks, Hispanics, and pacific islanders.
  • Obesity: Being obese or overweight increases your risk of sleep apnea. Obesity causes extra soft tissue to be deposited around the windpipe narrowing it and obstructing airflow. According to John Hopkins Medicine,
    ” Sleep apnea occurs in about 3 percent of normal-weight individuals but affects over 20 percent of obese people”.
  • Craniofacial deformities: The bony structure of the jaw and neck may be such that decreases the size of the airway in the mouth and throat area. The lower jaw may be structurally and abnormally longer than the upper jaw. Craniofacial deformities such as those developed in Marfan’s syndrome and Down syndrome can increase your risk.
  • Scoliosis: Similarly, having deformities of the spine such as scoliosis increases your risk of developing OSA.
  • Older age: Advanced age (above 65 years) causes limitations in the neurotransmission of brain signals, which keep the airway stiff during sleep. This can cause the collapse of the airway and obstruct breathing.
  • Smoking: Smoking significantly increases the risks.
  • Family history: People with sleep apnea often have a family history of it.
  • Endocrinal disorders: Certain endocrinal disorders such as hypothyroidism and acromegaly increase your risk of developing sleep apnea.
  • Thick neck: People with thicker necks usually have narrower airways, which predisposes to developing OSA.

OSA causes

  • In children, enlarged tonsils and adenoids in the upper airway are the most common cause of obstructive sleep apnea. Infection is the main reason for such enlargements.  The enlarged adenoids can completely block the nasal passages making breathing through the nose laborious.
  • An enlarged tongue can fall backward when you sleep and obstruct airflow through the windpipe. Conditions such as oral thrush or oral herpes can cause swelling of the tongue.
  • A deviated nasal septum can narrow the nasal airway obstructing airflow and breathing.
  • Swelling of the nasal filters (passageways) called turbinates can also obstruct airflow. Allergies or a lengthy cold or overuse of decongestant nasal sprays can cause these filters to swell making it difficult to breathe.
  • A long or floppy palate or uvula can fall backward when you sleep and obstruct the windpipe.
  • Obese people accumulate fat in the neck, tongue, and upper belly. This fat accumulation reduces the diameter of the throat and pushes against the lungs, contributing to airway collapse and sleep apnea.

Central sleep apnea (CSA)

Central sleep apnea (CSA) is much less common than obstructive sleep apnea and the symptom of snoring is less common.

It occurs due to the failure of the brain to send signals to the breathing muscles to carry on the process of breathing when the oxygen levels in the blood have dropped dangerously.

In CSA, apnea lasts for more than 20 seconds causing a severe drop in oxygen levels in the blood. CSA is also associated with a change in heart rate, low blood oxygen levels, and generally, more relaxation of body muscles (Hypotonia).

CSA risk factors

  • This type of sleep apnea is more common in infants (especially premature infants) because of a less developed respiratory center in the brain.
  • You also see it more in males and in people above the age of 65 years.
  • Adults with heart diseases such as congestive cardiac failure and cerebrovascular disease
  • In persons with neurological diseases such as encephalitis and stroke affecting the brain stem,
  • People with brain stem or spinal injury are at a risk
  • Some people with arthritis and degenerative diseases of the cervical spine and base of the skull may develop CSA
  • In a congenital disease called congenital central hypoventilation syndrome (CCHS), which is an extremely rare disease.
  • It can occur in places of high altitude

CSA causes

  • Certain narcotic painkillers including opioids such as morphine and codeine can disturb your breathing
  • High altitudes of 8000 feet above can induce breathing problems
  • Cheyne-Stokes breathing cycle can last 30 seconds to 2 minutes. In this condition, breathing speeds up, slows down, stops, and then starts again. About 50% of such patients develop CSA.
  • Some medical conditions can cause CSA. These include heart failure, Parkinson’s disease, stroke, infection in the brain, and end-stage kidney disease.
  • Some patients of obstructive sleep apnea who undergo CPAP treatment develop CSA.

CSA is seen in people with heart and lung disease because the carbon dioxide levels in the blood are higher than normal in such people. The brain is accustomed to these high carbon dioxide and low oxygen levels, and therefore, fails to respond as it should normally do.