In the wee hours or daybreak, one can't help but be cured of insomnia, for the sun is the nighthawks natural enemy. It only makes sense to blot out as much memory of it's risen hours as possible via voluntary hallucination infused unconsciousness.
Seriously though, look at sleep objectively. If we weren't so used to it it would seem like the strangest sensation... Suddenly being unable to move, but extremely relaxed. Seeing things that are ridiculous and haunting and wonderful all at once, yet being unable to remember them. Seeing ones fantasies and ones fears materialized, never really knowing for sure if one has truly experienced what one sees.
This is the true face of the dream, the true state of affairs for those who slumber.
