My room is "dark" but analyze: is it actually dark enough? Map the darkness: can I see my hand in front of face? Light under door? Electronic LEDs? Calculate: if I achieved complete blackness, would sleep improve? Show me the darkness hierarchy: these light sources matter most. Give me the blackout plan: block these lights in this order. Include: whether my "dark" is actually dark enough, sources I'm missing, and whether perfect darkness is necessary for me.