One cannot tell the difference between a body that is asleep at night and one who is died. Thus the reference of sleeping as the body is put aside until it is awaken again with the Spirit entering it and giving it life.

Jesus said-Luke 8:52 Now all wept and mourned for her; but He said, "Do not weep; she is not dead, but sleeping."

Matt 9:24 He said to them, "Make room, for the girl is not dead, but sleeping." And they ridiculed Him.

Luke 8:51-55 When He came into the house, He permitted no one to go in except Peter, James, and John, and the father and mother of the girl. Now all wept and mourned for her; but He said, "Do not weep; she is not dead, but sleeping." And they ridiculed Him, knowing that she was dead. But He put them all outside, took her by the hand and called, saying, "Little girl, arise." Then her spirit returned, and she arose immediately. And He commanded that she be given something to eat.

John 11:11 These things He said, and after that He said to them, "Our friend Lazarus sleeps, but I go that I may wake him up." v:14 Then Jesus said to them plainly, "Lazarus is dead.

John 12:1 Then, six days before the Passover, Jesus came to Bethany, where Lazarus was who had been dead, whom He had raised from the dead. V.17 Therefore the people, who were with Him when He called Lazarus out of his tomb and raised him from the dead, bore witness.