A simple mattress (standard size 90x200), either on the floor on a bed frame, is certainly not for everyone. But tastes differ, and it does have some advantages compared to the marriage bed and loft bed when it comes to sex. For one thing, it is so narrow that it invites physical contact. So when you go to bed together, cuddling is practically unavoidable and having sex is likely. While it does not offer as much space as a sensible futon bed, it is easy to move away from the wall in order to make room for creative positions.