I would suggest that Chopin was contrasting romance (wish fulfillment) to realism (role fulfillment). Her romance with Robert is both dangerous and wishful. Dangerous in that by allowing it to occur, she is putting herself in a situation where she goes against all societal convention. Likewise, there is also the danger of it turning into the husband/wife situation that she is so desperately trying to escape.
Her marriage represents reality. She is fulfilling the role that society has set out for her.
The contrast between sleep and awakening is metaphoric. Because society would not allow her to live up to her 'dreams', her awake or conscious state is therefore akin to sleeping. When she decides to break out of the traditional roles, or attempt to break out, she awakens from her sleep-like state of being.