In the Bible, the phrase “fallen asleep” is used as a euphemism for dead or died. It’s much the same as we might say “passed away,” “passed on,” or “passed.”
So when Jesus raises someone who has fallen asleep, he is not merely waking them up from a deep sleep or bringing them out of a coma, he is literally raising them from the dead.
This is aptly shown in the story of Lazarus (John 11:1-43). Here Lazarus is said to have fallen asleep. The disciples take this literally and assume that Lazarus is resting well and will recover from his illness. At that point Jesus tells them plainly, “Lazarus is dead.” Jesus later calls Lazarus from the grave and restores him to life.