In Psalm 127:1, this signifies a clear and alert state. (Arcana Coelestia 5210)

When a man begins to know that he does not live from himself, he wakes up. (Arcana Coelestia 147)

147. Verse 21 And Jehovah God caused a deep sleep to fall upon the man, and he fell asleep; and He took one of his ribs, and He closed up the flesh in its place.

'A rib', which is a breast bone, is used to mean man's proprium when it contains very little life, a proprium indeed that he cherishes. 'The flesh in place of the rib' is used to mean the proprium when it does contain some life. 'A deep sleep' is used to mean that state into which he was brought so that he might seem to himself to have a proprium. This state resembles sleep because a person in that state is conscious only of living, thinking, speaking, and acting from himself. But when he starts to realize that this is false, he is aroused from sleep so to speak and wakes up.