I sleep much better in real dark. I used to work night shifts, so have years of experience struggling to sleep with too much light. I never did adjust well to it. Now I probably take it too far, taping over the power light on the phone next to my bed, etc. But I know I sleep better with the blinds down even just to filter out the light from a full moon.

No doubt for a lot of people light isn't a problem with sleep at all, particularly for younger people.