What is the condition called when your heart temporarally stops in your sleep and may be fatal?

See Below: Likely pauses from sleep apnea or increased vagal tone (the slowing system of the central nervous system as opposed to the fast heart rate due the fight/flight system). This is usually benign unless associated with long pauses.

SUNDS: Sudden unexpected death syndrome, or sudden unexpected nocturnal death syndrome (sunds), is sudden unexpected death of adolescents and adults during sleep. The heart may go back into a normal rhythm thus avoiding death. Untreated sleep apnea may also cause irregularities in cardiac activity as well. An overnight sleep study or a halter monitor would yield the likely answer if you are concerned.