Obstructive sleep apnea occurs when the muscles in the back of your throat relax. These muscles support the soft palate, the triangular piece of tissue hanging from the soft palate (uvula), tonsils and tongue. When the muscles relax, your airway narrows or closes as you breathe in, and breathing momentarily cuts off. This may lower the level of oxygen in your blood. Your brain senses this inability to breath and briefly rouses you from sleep so that you can reopen your airway. This awakening is usually so brief that you don't remember it.

You can awaken with a transient shortness of breath that corrects itself quickly, within one or two deep breaths, although this is rare. You may make a snorting, choking or gasping sound. This pattern can repeat itself 20 to 30 times or more each hour, all night long. These disruptions impair your ability to reach those desired deep, restful phases of sleep, and you'll probably feel sleepy during your waking hours. People with obstructive sleep apnea may not be aware that their sleep was interrupted. In fact, many people with this type of sleep apnea think they sleep well all night.

Central sleep apnea, which is far less common, occurs when your brain fails to transmit signals to your breathing muscles. You may awaken with shortness of breath or headaches. The most common cause of central sleep apnea is heart disease. People with central sleep apnea may be more likely to remember awakening than people with obstructive sleep apnea are.

Causes and Risk Factors of Sleep Apnea:

• Shape of head and neck may create a smaller than normal airway.
• Large tonsils or adenoids or other anatomical differences. (A deviated septum, enlarged tongue, or receding chin can also create difficulties breathing during sleep).
• Being overweight or obese (although almost 50% of people with sleep apnea are not obese).
• Throat muscles and tongue relax more than normal during sleep. (This can be due to alcohol or sedative use before bedtime, but not necessarily).
• Snoring - Snoring can cause the soft palate to lengthen, which in turn can obstruct the airway.
• Smoking or exposure to secondhand smoke.
• Nasal congestion, nasal blockages, and nasal irritants.
• Family history of sleep apnea - No specific genetic marker for sleep apnea has been discovered, but obstructive sleep apnea seems to run in families. This may be a result of anatomic abnormalities that run in the family.
• Other disorders and syndromes - Hypothyroidism, Acromegaly, Amyloidosis, Vocal Cord Paralysis, Post-Polio Syndrome, Neuromuscular disorders, Marfan'sSyndrome, and Down Syndrome.
• Other physical conditions, such as immune system abnormalities, severe heartburn or acid reflux and high blood pressure. It isn't clear whether the conditions are the cause or the result of sleep apnea.