Sleep Disordered Breathing (SDB)

Sometimes during sleep, the body either forgets to breathe, has a hard time breathing, or is unable to pass air even when trying to breathe. This is called sleep disordered breathing (SDB).

Sleep disordered breathing, also called sleep apnea, was first described in the late 1800s. Yet it was only 25 years ago that doctors recognized it as a serious problem. The word apnea comes from the Greek words "a," which means absence of, and "pnoia," which means breath. Sleep apnea syndrome is defined as breathing that temporarily stops during sleep. You fall asleep; you stop breathing; to start breathing again, you wake up; you start breathing; you fall back to sleep; you stop breathing. This cycle continues throughout the night. The awakenings you experience are so brief that you are not aware of them, but they are long enough to help you start breathing again and long enough to disrupt your sleep.

The most common type of SDB is obstructive sleep apnea. Normally, the air you breathe passes from your nose and mouth through your throat to your lungs. The portion of the throat just above the larynx (the voice box) is soft and flexible so you can swallow and so you can make the sounds needed for whispering, talking, singing, and yelling.

For the diagnosis of SDB to be made, each apnea episode must last a minimum of 10 seconds and must occur at least 5 times for each hour you are asleep. Partial decreases in breathing, called hypopneas, may also produce brief awakenings even when complete apneas do not occur.

The soft palate is the tissue at the back of the roof of your mouth that blocks the passage leading to your nose when you swallow. This stops food from going up into your nose. The uvula is the flap that hangs down in the back of your throat. Your tonsils are globules of tissue far back on both sides of the throat that frequently swell and become tender during throat infections, especially in children. Muscles hold the airway open by keeping each structure tight and in place.

During sleep the muscles relax a little, but in a normal person, air can still pass through. When any of these structures is anatomically abnormal, air is prevented from freely flowing during sleep, causing snoring and Sleep Disordered Breathing. Obstructive sleep apnea occurs when the muscles of the airway collapse, resulting in partial or complete blockage of airflow. You still attempt to breathe, your diaphragm is still moving, but the collapse of the airway muscles blocks your airway, so the air cannot get in or out. Therefore the reason you stop breathing is that when you fall asleep, the muscles in your airway collapse, blocking the air from going through. When you wake up, even briefly, the airway opens again.

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