Minecraft wiki entry for Shelters, associated text: Sleeping in a bed resets your spawn point to that bed. It's a pretty good idea to have this in a secure bunker. It's also a good idea to keep this room far from the outdoors, so a mob cannot prevent you from sleeping or blow up your bed. For added safety against creepers creeping up on you or PVP griefers in your sleep, use three-layered walls, with the middle one being Obsidian or Water.