Obstructive sleep apnea (OSA) is characterized by episodes of breathing cessations during sleep. It is the most common type of sleep apnea and is caused by the intermittent relaxation of the throat muscles which block the airway. The symptoms include restless sleep, often feeling sleepy during the day, loud snoring, insomnia, frequent urination at night, heart burn, GERD, mood changes, and night sweats. The risk factors include old age, obesity, long-term snoring, and brain injury. Treatments include using a device to keep the airway open, a mouthpiece which thrusts the lower jaw forward, and surgery.