Obstructive sleep apnea (OSA) is a common sleep apnea caused by obstruction of the airway. It is characterized by pauses in breathing during sleep. These episodes, called apneas (literally, "without breath"), each last long enough that one or more breaths are missed, and occur repeatedly throughout sleep. In obstructive sleep apnea, breathing is interrupted by a physical block to airflow, despite the effort to breathe.

Common signs of obstructive sleep apnea include unexplained daytime sleepiness, restless sleep, and loud snoring (with periods of silence followed by gasps). Less common symptoms are morning headaches; insomnia; trouble concentrating; mood changes such as irritability, anxiety and depression; forgetfulness; increased heart rate and/or blood pressure; decreased sex drive; unexplained weight gain; increased urination and/or nocturia; frequent heartburn or Gastroesophageal reflux disease; and heavy night sweats.

Most cases of OSA are believed to be caused by:

• old age (natural or premature),
• brain injury (temporary or permanent),
• decreased muscle tone,
• increased soft tissue around the airway (sometimes due to obesity), and
• structural features that give rise to a narrowed airway.

Decreased muscle tone can be caused by drugs or alcohol, or it can be caused by neurological problems or other disorders. Some people have more than one of these issues.

Old age is often accompanied by muscular & neurological loss of ability of the airways. Premature aging is temporarily caused by chemical depressants; alcoholic drinks being the most common. Permanent premature airway aging may be caused by traumatic brain injury, or poor adherence to chemical and or speech-therapy treatments.

Individuals with decreased muscle tone, increased soft tissue around the airway, and structural features that give rise to a narrowed airway are at high risk for obstructive sleep apnea. Men, whose anatomy is typified by increased body mass in the torso and neck, are more typical sleep apnea sufferers, especially through middle age and older. Adult women suffer typically less frequently and to a lesser degree than men do, owing partially to physiology, but possibly to emerging links to levels of progesterone. Prevalence in post-menopausal women approaches that of men in the same age range.

The treatment of obstructive sleep apnea depends in part on the severity of the condition. Treatment options include:

• Dental devices: Dental devices, also called oral appliances, are custom-made mouthpieces that help position the lower jaw and tongue during sleep. Dental devices may be helpful for mild cases of obstructive sleep apnea.
• Breathing devices: Continuous positive airway pressure (CPAP) devices are the most common treatment for moderate-to-severe obstructive sleep apnea. Although these devices can take some time to get used to, they are a very effective treatment.
• Surgery: Various surgical procedures may be recommended for severe cases of obstructive sleep apnea.