For babies, a crib with a firm, tight-fitting mattress is crucial to the infant's health and safety. Make sure the crib has adequate support for the mattress, so that the bedding can't be easily dislodged. Otherwise, your baby could fall through the slats. Many parents consider the crib mattress an afterthought, but it's the most important item, since babies spend almost three-quarters of their time asleep and toddlers spend half their time sleeping.

As your children grow older, they are probably ready to graduate to a twin bed. The rules of comfort and support apply here. Children need 8-10 hours of sleep per night (although as we all know, they try to get away with less.) A mattress that allows them to sleep comfortably while preventing them from moving around too much will give them the restful sleep they need to grow up healthy.

Also, do not give a child your old mattress when you buy a new one. If a mattress is no longer comfortable for you, it will not be so for your child.