Hades

The Gray Waste of Hades was an Outer Plane, and eighth layer of the Nine Hells. It had magical connections to the Shadowfell, and was said to be a representation of the Shadowfell (and therefore, Echelon) if good in the Material Plane was snuffed out. It was considered neutral evil in alignment, with nothing but gloomy regions devoid of emotion, hope, and peace in all directions.

Like in Pandemonium, a person could not sleep in Hades. However, instead of adrenaline-fueled madness resulting from the lack of sleep, dreamless nights in Hades would eventually result in overwhelming ennui.