Last week a student asked me if it was a bad thing for brothers to share a bed while growing up. He said he had and his brother had shared a bed when they were kids, and some of his friends think it was strange and maybe even sick. I said it's not strange or sick at all, and it's even quite common. In my Two in a Bed research, 33 of the 88 adults I interviewed said they had experience sharing a bed as a child. Most often they shared a bed with one or more siblings or with a grandmother. Some did it for years.
Reasons for Child Bed-Sharing
Children share beds for all sorts of reasons. But one of the most common is that there aren't enough beds in the household to go around. Often because of economics and sometimes because people live where there isn't much space, the family needs children to share a bed. In fact, for poorer families in the U.S. or other countries, it would be strange for a child not to share a bed with someone. Most children do.
But it's not all about economics. There is security in sharing a bed, security that comes with another person very near and possibly the security that comes with touching and being touched. Whatever is scary in the night is probably less scary when someone else is near.
Then there is the warmth factor. Some grandparents appreciate the extra body heat from a child in bed with them, particularly in winter. And on cold winter nights, many children are also glad to have a warm person in bed with them.
Some children don't fall asleep right away and enjoy chatting and giggling with a bed companion. For some children, touching a sibling or grandparent can feel comfortable and reassuring. I also interviewed in one family where the mother wanted her children in bed with her because it protected her from her husband's abusiveness.
Guesses about Human Evolution
I think humans evolved sleeping together, and that is especially so for infants and young children. It is only in recent times and almost only for economically well-off households that there is so much sleeping in separate beds (and even in separate rooms). In fact, in research I did using 19th century diaries, most people who mentioned their sleeping situation said that they shared a bed with other family members. Some even shared their bed with servants, farm hands, and visiting strangers who were passing through and needed to spend the night. So in evolutionary perspective, what might be strange is to grow up not sharing a bed.
Long Term Gains from Childhood Bed-Sharing
Some of the people I interviewed said that having shared a bed in childhood was a real help to them in their adult bed-sharing. They learned how to sleep parallel to the long side of the bed. They learned how to stay on their part of the bed when they wanted to do that and to keep the other person from invading their space if they didn't want that. They learned how not to steal covers and pillows and to protect their covers and pillows from being stolen. They learned not to be bothered much by the tossing and turning, sounds, and smells of a bed-partner. So when they got into an adult bed-sharing relationship with a romantic partner, sharing a bed was generally easy for them.