Sleep apnea is a serious sleeping disorder. It occurs when patients stop breathing while they’re sleeping. Sleep interruptions may occur infrequently or hundreds of times per night, which causes the brain to receive insufficient amounts of oxygen. Sleep apnea occurs in one of two manifestations. The airway becomes blocked during sleep when patients have obstructive sleep apnea (OSA). Central sleep apnea (CSA) is a disorder in which brain signals fail to control breathing while you sleep.