I don’t like to sleep in near pitch black rooms. It just feels unnatural to me. It may be more the fact that it prevents the gradual transition to daylight unless you’re using an artificial light, so that bothers me more because you don’t know when morning is. But even when traveling I love to keep the curtains open through the night and sleep to whatever the natural light level is around me even if it’s in the middle of a city.
Hmmm I can see your point, but on the other side, think about how our species evolved, to sleep in very dark conditions. It seems to me that it’s more natural to sleep in the dark and waken with the gradual lightening of the sky at dawn. So I guess I agree you with you that we shouldn’t go from full dark to full bright with the flick of a switch. For myself, I keep the blinds open and wake with the dawn, and always feel very rested.