Sleep apnea is a breathing disorder characterised by interruptions of breathing during sleep. There are two types of sleep apnea:

• Central sleep apnea occurs when the brain fails to send the right signals to the breathing muscles to start breathing.
• Obstructive sleep apnea occurs when air cannot flow into or out of the person's nose or mouth although efforts to breathe continue.Obstructive sleep apnea is much more common than central sleep apnea. In obstructive sleep apnea, the throat collapses or is obstructed during sleep causing the individual to snort and gasp for breath. Hundreds of these episodes can occur every night causing daytime sleepiness and, it is thought, increasing the risk of hypertension (high blood pressure) and heart problems.