Contrary to what we find in Psalm 3, in this psalm the problem is one of malicious slander and lies. It is the psalmist's reputation rather than his person that is being attacked, and what he needs is a sense of the presence and approval of God rather than physical deliverance.

The last section of the psalm is a confident cry for God's deliverance, because the psalmist knows that God has heard him and will provide deliverance. 

To many people the most appealing part of this psalm is the third stanza, the part in which David tells how he was able to lie down and sleep even in the midst of the sudden great danger occasioned by Absalom's rebellion (vv. 5-6). It is a beautiful picture of one so trusting in God that he is able to sleep soundly even while the treacherous seek his life.

Much happens in this psalm in the space between the first two stanzas, marked out by selah. The first stanza is an expression of the crisis that has come into the psalmist's life because of the enemies who have risen up against him. The second stanza is a quiet expression of his confidence in God. What has produced this abrupt but obvious change? The answer is that he has turned his attention from his enemies to God.

So the psalm is not speaking of some vague problem or disappointment but rather of a specific danger David faced that specific morning. I am sure that many people can identify with that. Perhaps you are one. You may not be facing an imminent military battle when you wake up most mornings, but you are facing a battle.