Sleep apnea is a sleep disorder where a person has pauses in breathing or periods of shallow breathing during sleep. Each pause can last for a few seconds to a few minutes and they happen many times a night. In the most common form, this follows loud snoring. There may be a choking or snorting sound as breathing resumes. Because the disorder disrupts normal sleep, those affected may experience sleepiness or feel tired during the day. In children it may cause hyperactivity or problems in school.

Sleep apnea may be either obstructive sleep apnea (OSA) in which breathing is interrupted by a blockage of air flow, central sleep apnea (CSA) in which regular unconscious breath simply stops, or a combination of the two. Obstructive (OSA) is the most common form. Risk factors for OSA include being overweight, a family history of the condition, allergies, a small breathing airway, and enlarged tonsils. Some people with sleep apnea are unaware they have the condition. In many cases it is first observed by a family member. Sleep apnea is often diagnosed with an overnight sleep study. For a diagnosis of sleep apnea, more than five episodes per hour must occur.