a deep sleep that comes over a person from outside, sealing off the senses so that something is done to them while they lie helpless and unaware
This is not the ordinary sleep of a tired body. It is a heavy, overpowering sleep that falls on a person from outside, and in the Bible it almost always comes from God. The person it falls on goes completely passive: their senses are shut off, and they take no part in what happens next. The name itself may go back to an old word meaning to block or stop up, which fits a sleep that seals a person off.
Six of its seven appearances are caused directly by God, and they cluster at turning points in the story. God makes a deep sleep fall on the first man so the woman can be formed, on Abram so a covenant can be sealed, and on Saul's whole camp so David can walk through it untouched. In the book of Job it is the setting in which a vision comes at night. In each case the human is set aside so that God can act or reveal without their help, which is why the word carries far more weight than plain sleep.
Two passages bend the pattern rather than break it. In Isaiah, God pours out a deep sleep as judgment, dulling people's eyes and minds so they cannot see or understand. In Proverbs, the same heavy sleep is what laziness brings on, a hollow echo of the God-sent sleep that leaves the sluggard with nothing but hunger. Both of these depend on the reader already knowing that this sleep normally falls from God.
Nuances
Whether the deep sleep of Genesis 2:21 is functional unconsciousness (God simply puts the man under so the woman can be formed without his participation) or a visionary trance in which he receives revelation.
- majorityFunctional unconsciousness: a narrative device shielding the woman's formation from human cooperation, not a vision.; C. Westermann, Genesis 1-11 (Continental); G. J. Wenham, Genesis 1-15 (WBC), p. 69; K. A. Mathews, Genesis 1-11:26 (NAC)
- minorityA visionary trance in which the man beholds prophetic mystery, weighted by the Septuagint's choice of the word for ecstasy.; J. H. Walton, The Lost World of Adam and Eve, pp. 77-81; B. K. Waltke, Genesis, pp. 89-90; Augustine, De Genesi ad litteram 9.19