Sartre's Rejection of the Unconscious- relating to dreams

Sartre is very committed to his concept of freedom void of any predisposition (determinism).  He even rejects the scientifically supported notion that dreams are controlled by our unconscious.  What would this mean then, that even while we rest our mind is wide awake and able to make decisions?  Do we never truly sleep?  I might be completely misunderstanding what the concept means, and if you know better what the reaches of Sartre's ideas are please offer your opinion.  To what did Sartre credit dreams? How did he feel it contributed to our personal essence? If we freely choose our dreams would that take a recognizable selection before we lay down to establish the course of the night's dreams?