There are numerous synonyms for the word "sleep-filled" that one can use to describe a deep and restful slumber. Several options include "slumberous," "somnolent," "heavily-laden with sleep," "droopy," and "drowsy." Other synonyms that convey a state of deep sleep are "reposeful," "restorative," "peaceful," and "tranquil." For a more poetic or flowery description, one could opt for "dreamy," "soporific," "serene," or "mesmeric." Ultimately, the choice of synonym will depend on the context and tone of the sentence, with each word offering a slightly different nuance to the idea of sleep-filled bliss.