Jamieson, Fausset and Brown on Ephesians 5:14

14. Wherefore--referring to the whole foregoing argument (Ep 5:8, 11, 13). Seeing that light (spiritual) dispels the pre-existing darkness, He (God) saith ... (compare the same phrase, Ep 4:8).

Awake--The reading of all the oldest manuscripts is "Up!" or, "Rouse thee!" a phrase used in stirring men to activity. The words are a paraphrase of Is 60:1, 2, not an exact quotation. The word "Christ," shows that in quoting the prophecy, he views it in the light thrown on it by its Gospel fulfilment. As Israel is called on to "awake" from its previous state of "darkness" and "death" (Is 59:10; 60:2), for that her Light is come; so the Church, and each individual is similarly called to awake. Believers are called on to "awake" out of sleep; unbelievers, to "arise" from the dead (compare Mt 25:5; Ro 13:11; 1Th 5:6, with Ep 2:1).

Christ--"the true light," "the Sun of righteousness."

give thee light--rather, as Greek, "shall shine upon thee" (so enabling thee by being "made manifest" to become, and be, by the very fact, "light," Ep 5:13; then being so "enlightened," Ep 1:18, thou shalt be able, by "reproving," to enlighten others).