There are two words rendered "Sleep" : --
1. katheudo = to compose one's self for sleep. Occurs twenty-two times; never used of death.
2. koimaomai = to fall asleep (unintentionally).
Hence this latter is used of death, as it is involuntary while katheudo
is voluntary. See this difference illustrated in 1Thess. 4:14 (where
it is koimaomai), and 5:6, 7, 10 (where it is katheudo).
Occurs eighteen times; always of death, save Matt. 28:13. Luke 22:45.
John 11:12. Acts 12:6.