I co slept as a preteen with my two younger (2 & 4 yrs younger than me) sisters, sideways in a double bed (it may have been a queen bed) Can't remember how old I was (i know i was older than 7) or how old the youngest sister was. I have a vague idea it was done as my parents couldn't afford single beds for us at the time and my brothers. We just accepted that it was bedtime & went to sleep. I have vague memories if the occasional disagreement as to who was sleep in the middle and who had which end but nothing else stands out as unusual from that time.

ETA this was in the mid-late 80s