A good night's sleep is essential for good health. It makes you feel rested and ready to take on the world. Yet many people don't get the sleep they need. Sometimes this is related to sleep-related breathing disorders (SRBD) — their own, or those experienced by their sleeping partners. Sleep Apnea is characterized by recurrent episodes of reduced or interrupted respiratory airflow. This is caused by soft tissues near the back of the throat collapsing during sleep so that they partially close off the windpipe. These tissues — the tongue, for example — can vibrate as air passes by, causing snoring. Snoring is often worsened sleeping on one's back because this encourages the lower jaw to slip back, which in turn pushes the tongue in front of the airway. Loud snoring often disturbs the person in the bed who isn't the one doing it, robbing him or her of vital sleep. The snorer, on the other hand, may seem to be slumbering peacefully, but this might not actually be the case. Chronic loud snoring is a common symptom of Obstructive Sleep Apnea (OSA; “a” – without; “pnea” – breath), which occurs when the upper airway is blocked to the point of causing significant airflow disruption, or even no airflow whatsoever for 10 seconds or more. This can be dangerous as reduced airflow into the lungs lowers blood-oxygen levels. A person with sleep apnea may wake 50 or more times per hour — that's almost once a minute! — without having any memory of it. These awakenings, called micro-arousals, last just long enough to restore muscle tone to the airway so the individual can breathe. Unfortunately, all those micro-arousals prevent deep and restful sleep.