There are various synonyms for the phrase "in a state of sleep" that can help us to describe this common state of unconsciousness. Some of the most commonly used synonyms include being asleep, slumbering, dozing, snoozing, napping, resting, and drowsing. Each of these terms describes a slightly different variation of sleep, with "slumbering" indicating a deep and peaceful rest, while "dozing" and "drowsing" suggest a lighter and less restful state. Similarly, words like "snoozing" and "napping" imply a shorter duration of sleep, while "resting" could indicate a person who is lying down but not fully unconscious. Overall, each of these synonyms provides a useful alternative to the simple phrase "in a state of sleep".