Insomnia

Insomnia is a mechanic in Minecraft that allows phantoms to spawn around players that have not entered a bed or died for three in-game days (1 hour or 72000 ticks). This value is specifically defined by the "Since last rest" statistic and can be disabled with the command “/gamerule doInsomnia false.” 
Insomnia may refer to:
* Phantoms - phantoms may only spawn when a player has insomnia.
* Sleeping - Sleeping or entering a bed are methods to reset the insomnia counter.
* - A gamerule that enables or disables insomnia, and thus, phantom spawning.