I need at least sheets that are thick enough not to let light through, not super thin sheets. It’s annoying in summer months. I need my feet covered because I’m paranoid about mosquitos though it’s rare for them to actually get inside and I need my head/eyes covered as well or it just doesn’t feel right, partly about light and muffling noise.

And for me it’s definitely a horizontal sleeping thing too. Propped up I can fall asleep while being only partially covered or hardly at all but horizontal I have to have it.