What does Psalm 6:6 mean?

The cause for David's misery is not given in this psalm. It might have been anguish over his own personal sin, or the effects of a disease, or both. He might have been suffering from a dire threat from enemies. In his misery, David wept profusely. His tears drenched his bed and couch.

In another of the "penitential Psalms," David says he was feeble and crushed and he groaned (Psalm 38:8). David states: "O Lord, all my longing is before you; my sighing is not hidden from you" (Psalm 38:9). Adding to his misery, his friends and relatives have forsaken him and his enemies plot to destroy him (Psalm 38:11–12). David had known peaceful sleep in the past. In Psalm 4:8 he writes: "In peace I will both lie down and sleep; for you alone, O LORD, make me dwell in safety."

Somehow David's confidence in the Lord, which had allowed him to sleep securely, had vanished. Now he cannot sleep at all. Loss of confidence in the Lord as our protector can cause us, too, to weep and lose sleep.