ציטירנדיקער פּירוש אויף דניאל 8:18

ותרדמה נפלה על אברם, this exhaustion was due to the marshalling of all of Avram’s spiritual resources to receive these prophetic visions. We have evidence of these reactions in Daniel 8,18 who describes these physically debilitating reactions when he involuntarily went to sleep on the very ground on which he had been standing. (he did not have time to lie down on a bed) He had to be revived by the angel. He referred to such weakness also in verse 17 of that same chapter. Avram, at least at the beginning of his prophetic vision, did not experience such a weakness. The reason was that at the beginning of the visions G’d showed him there were only positive developments. Now when G’d showed him the downside, he was overcome with the impact of what G’d showed him.