A bed is a block (or, two blocks) that the player can make to sleep through the night. The players spawn point is reset to the bed, although if it gets destroyed, you spawn at your original spawn point. A player cannot sleep if monsters are nearby, displaying the message 'You cant sleep now, there are monsters nearby!' In Multiplayer, all players in the Overworld must be asleep. If you try to sleep in the Nether or the End, the bed will explode, causing an explosion more powerful than TNT.