when one has sleep apnea, their body fails to gain enough oxygen or even just breathe. a solution for that is a cpap/bipap. a cpap is made for obstructive sleep apnea (meaning something is blocking your throat from getting enough air down) and a bipap is made for central sleep apnea (when your brain fails to remember to take a breath). ive technically got a bipap that's been instructed to work as a cpap.