The story says that during the persecutions by the Roman emperor Decius, around 250 AD, seven young men were accused of following Christianity. They were given some time to recant their faith, but they refused to bow to Roman idols. Instead they chose to give their worldly goods to the poor and retire to a mountain cave to pray, where they fell asleep. The Emperor, seeing that their attitude towards paganism had not improved, ordered the mouth of the cave to be sealed.
Decius died in 251, and many years passed during which Christianity went from being persecuted to being the state religion of the Roman Empire. At some later time—usually given as during the reign of Theodosius II (408–450)—in 447 A.D. when heated discussions were taking place between various schools of Christianity about the resurrection of the body in the day of judgement and life after death, a landowner decided to open up the sealed mouth of the cave, thinking to use it as a cattle pen. He opened it and found the sleepers inside. They awoke, imagining that they had slept but one day, and sent one of their number to Ephesus to buy food, with instructions to be careful.
Upon arriving in the city, this person was astounded to find buildings with crosses attached; the townspeople for their part were astounded to find a man trying to spend old coins from the reign of Decius. The bishop was summoned to interview the sleepers; they told him their miracle story, and died praising God. The various lives of the Seven Sleepers in Greek are listed and in other non-Latin languages at BHO.