I grew up in a house that had the massively thick kind of exterior blinds everywhere, the ones that really make your room pitch dark ("Außenrolläden" in my nati

I grew up in a house that had the massively thick kind of exterior blinds everywhere, the ones that really make your room pitch dark ("Außenrolläden" in my native language). After moving out from my parent's house I have lived in several places, but often in older buildings without decent blinds. I didn't realize the influence this may have had on me before a temporary room mate pointed out that the room is far too bright for her at night. Sleeping masks did not help me too, so I got thick blackout curtains for my next flat, and the first effect was that I suddenly had vivid dreams again regularly, which I only had occasionally in the years before. I am considerably more alert during the day now. In retrospect I indeed must have felt constantly slightly tired for years during the day, after sleeping in such rooms. It is possibly dangerous to sleep in even slightly light rooms. The lowered levels of melatonin are correlated to several bad illnesses (just look it up). I push my SO who still sleeps in a too bright apartment to regularly wear his sleeping mask at least, but people who have never slept in really dark rooms for prolonged time may simply not have the experience points here.