Buying a mattress for a child needs to be considered and researched before purchasing as it will come to play a big role in their life as they grow in weight and height. It’s important to regard a mattress as an investment piece that your child will feel the benefit of every night (and every day) for a good number of years. For example, if you’re buying a mattress for a younger child, say 3 to 4 years old, you should plan to replace it within 7-8 years.