Sleep apnea is a breathing condition where the person stops breathing for a few seconds or minutes. It can be caused by a number of different factors, but the main cause is usually obesity. The person's voice will change and they will not be able to breathe out of their nose. Snoring is when a person snores loudly and in an irritating way. It may also occur when someone has sleep apnea, but it can also occur with other breathing disorders like obstructive sleep apnoea (OSA).