Matthew Poole and continuators on Numbers 24:4

4 He hath said, which heard the words of God, which saw the vision of the Almighty falling into a trance , but having his eyes open:

So called either strictly and properly, because he was awake when this was revealed to him: or largely and improperly, for any extraordinary discovery of Gods mind to him, whether sleeping or waking.

Or, extasy, fainting and falling upon the ground, as the Prophets used to do. See 1 Sam. 19. 24. Ezek. 1. 28. and 3. 23. and 43. 3. Dan. 8. 17, 18. and 10. 16. Rev. 1. 17. Others, falling suddenly into a sleep, as the Prophets sometimes did, as Gen. 15. 12. Dan. 8. 18.