a recessed nook becomes a headboard for the bed. I think I'd take the nook all the way to the ceiling to avoid it looking like you put the bed in a repurposed closet; and put the ledge up higher, so that you can recline against the wall
UK artist Rachel Dein’s method of plaster casting captures everyday objects in a unique and delicate way. She makes impressions in wet clay, and then pours plaster directly over them. The clay captures.