It all depends on the age of the child, but the air mattress is stable, so as soon as your child can sleep on a 'normal' bed, he or she will be able to use this extra mattress.

Sorry, we didn't test this with my 11 year old daughter's friends. Let's just say that it looks really solid and of good quality, but for sleeping rather... because the mattress is inflatable, it will not have the same stability as a standard mattress. After that, for an inflatable, it's strong.