In addition, Freud and his contemporaries did not know that we forget many more dreams than we remember. We normally only remember a dream if we happen to wake up during the dream, and if we don't make a conscious effort to continue to remember that dream, we will soon forget it. The function of REM sleep therefore must have more to do with what is happening in our brains when we are unconscious - when we are dreaming and forgetting - than with the few dreams that we remember.