I live on my own in a tiny one bedroom flat. My bedroom is 7 foot by 9 foot. I have a double bed pushed up against one wall, a small wardrobe and a bedside table.
Would it be crazy for an adult in their late 30s to have a loft bed?? Ideally a double but think that would need to be custom made but I could easily manage with a single. I'm never going be sharing a bed with anybody.. no kids and no partner and there will never be a partner.