The phrase "need to sleep constantly" can be expressed in a variety of ways. You could say that someone "requires frequent rest," "has an insatiable need for sleep," or "craves regular napping." Other synonyms for this phrase include "adds up z's regularly," "has a compulsive urge to snooze," or "feels a constant need for shut-eye." In more medical terms, someone who needs to sleep constantly might be described as having an "excessive hypersomnia condition," or being in a state of "chronic sleepiness." No matter how you say it, needing to sleep constantly can indicate a potential sleep disorder or underlying health issue that should be addressed.