In fact, he and Moses were the two Old Testament saints who appeared with Jesus on the Mount of Transfiguration. Yet Elijah had such an emotional collapse after his great victory at Mount Carmel that he begged God to let him die. Instead of scolding, the Lord sent an angel with some food and let him go back to sleep. When rested, he was ready for another assignment. Occasionally sanctified people experience deep clinical depression that requires medical attention.
Causes are often mysterious and complex, but generally some kind of chemical imbalance is involved.
During this terrible time they may feel deserted by God and man. In extreme cases supersensitive souls battle with feelings of lostness, even fearing that they have sinned away their day of grace. When they come out of this black tunnel, their assurance is reaffirmed. Of course those who are spiritually mature and acquainted with the ways of God are more apt to come through these experiences with some understanding of what is happening. It is easier for them to hold steady and believe God is with them whether they feel His presence or not.