Minecraft wiki entry for The_second_day, associated text: When trying to sleep, make sure it's either night-time or storming (not just rain), and there are no monsters around you. If there is a problem, you should get a status message explaining what's wrong. You can't sleep if you are currently starving, poisoned or on fire. If trying to sleep at sundown, you may need to wait a few seconds for night to officially begin, and try again.