Sleep World is one of the three main worlds in PHOGS! It contains 7 levels focused around the theme of sleeping and night time.
SPOILERS AHEAD
<spoiler> Sleep World, sometimes known to the PHOGS! community as "Nighty night zone" and "The Domain of Eternal Slumber" is a realm that has been cast into a deep slumber by The Midnight Dragon, when he grew jealous of his older brother The Midday Dragon. The citizens of this world include a moth, light orbs (unsure if those are alive) a spider, dream-nozzle ogres, alarm children, and many animate teddy bears. The Midnight Dragon's curse is broken by Red and Blue at the end of the 7th level. </spoiler>