Close the door, turn out the light, close the blinds, turn the curtains. Lie back with shut eyes and pray that sleep will take you. As soon as you try the fatigue vanishes and insomnia takes hold, and your eyes stay wide open against the darkness which presses upon them. They itch and burn and cry to be left alone in dark contentment, but the mind churns and whirls and thoughts dance across your consciousness, never allowing your eyes a moment's rest.
The black is supposed to help, but even where the sun doesn't shine, you are offered no relief, no release from the struggle to stay coherent. People pass back and forth, ignoring the unremarkable door which shields you from the day. It's not that people don't know what happens behind closed doors, it's that they don't even care to find out.