Meaning: The rabbit continuously slept throughout the entire night.
Choice of Words: Rabbit is the subject, slept is the verb, all night long is an adverbial phrase.
Meaning: This means that the rabbit was asleep for the entire night.
Choice of Words: Slumbered is a more formal word for slept. Nocturnal means relating to the night. Hours is a noun that means a period of time.
Meaning: This means that the rabbit was asleep until the sun came up.
Choice of Words: Bunny is another word for rabbit. Dozed means to sleep lightly. Dawn means the first light of day.