Sleep apnoea caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. In cental sleep apnoea, the airway is not blocked but the brain fails to signal the muscles to breathe.

Untreated, sleep apnoea can cause high blood pressure and other cardiovascular disease, memory problems, weight gain, impotency, and headaches.

There are different reasons why breathing may stop during sleep, and those reasons help classify sleep apnoea as either:

• Central Sleep Apnoea
  In individuals suffering from Central Sleep Apnoea, the brain does not signal the chest muscles to work during sleep, and breathing stops.

• Obstructive Sleep Apnoea (OSA)
  OSA is the most common type of sleep apnoea. Patients with OSA breathe normally, but the air is momentarily blocked from entering the lungs because the upper airway collapses during sleep.

• Mixed Sleep Apnoea
  This type of sleep apnoea is the most complex to treat. In Mixed Sleep Apnoea, the brain periodically fails to trigger breathing, and when the sleeper does try to breathe, he or she can’t because the upper airway has collapsed.

During OSA and Mixed Sleep Apnoea, the upper airway collapses. The upper airway is a floppy tube supported by muscles, and it runs from the mouth to the lungs. When you lay down to sleep, your muscles relax. With gravity at work, it’s natural that the airway narrows when you lie down, but in some people, it narrows too much. When the person breathes in, the air struggles to get through the narrowed passage and as it squeezes through, the air tube rattles. The noise that is created is what you hear when a person snores. Many sleep apnoea sufferers are also snorers.

When the airway is blocked and breathing stops during sleep, you are being momentarily choked, and the sudden drop in oxygen level causes carbon dioxide levels in the blood to rise. The body tries to protect itself from harm by making the heart work harder to move the remaining oxygenated blood through the body. So, your heart rate increases too.
As a result, sleep apnoea can cause:

• High blood pressure
• Heart attack
• Stroke
• Impotence
• Irregular heartbeat
• Heart disease