In a general sense, sleeping in the Bible represents a state of obscurity about spiritual matters, a state in which you are not recognizing things that are spiritually true and not seeking what is spiritually good. In particular -- especially when someone is in a "deep sleep" -- it represents a state in which we believe we think, feel and do everything from ourselves, without acknowledging that all life comes from the Lord.

(References: Arcana Coelestia 147, 150, 3715, 5210)