So the LORD God caused a deep sleep to fall upon the man: So marks a consequence of the reason given in verse 20, “Therefore, As a result, Consequently.” Caused … to fall is idiomatic in Hebrew, as is the English “So God put the man to sleep” or “… made the man sleep soundly.”

The word rendered deep sleep refers to an unconscious or altered state of the mind and body. It is normally caused by God acting on individuals or groups. In 15.12 such a sleep is said to have fallen upon Abram when the LORD tells him what will happen to him and his descendants. In 1 Sam 26.12 the LORD sends a deep sleep upon Saul and his army. This is more than ordinary sleep, and since it is cause by the LORD, it does not end until the LORD is ready to remove it.

Took one of his ribs means that he removed it from his body. That is, “While the man was sleeping God removed a rib from the man’s body.”

And closed up its place with flesh: this indicates that a cut or hole resulted from the removal of the rib, which then had to be closed. Closed up … with flesh will often be expressed as “closed up the flesh,” “healed the hole,” or “closed and healed the cut.”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .