Sleepful has a variety of synonyms that you can use depending on the context of the sentence. Words that can be used to replace sleepful include restful, peaceful, relaxing, calm, soothing, tranquil, and serene. These synonyms all convey a sense of calmness and relaxation that is associated with getting a good night's rest. For example, you might say that you had a restful sleep after a long day at work. Alternatively, you could describe a relaxing evening in with a book and a cup of tea as sleepful. Whatever word you choose, make sure it reflects the peaceful state of mind you experience when you are well-rested and refreshed.