When choosing a convertible sofa, one of the most important considerations is the type of mattress that will be used as well as its thickness. For occasional sleeping, a foam mattress is a good option. These mattresses are relatively light . You need to look at the density of the mattress, ideally greater than 28kg/m3. Some products are not necessarily as comfortable as the mattress of a bed intended for daily sleeping which must have a density greater than 40kg/m3. The same goes for the thickness which must be greater than 6cm for occasional sleeping vs. 14cm for regular sleeping. Ultimately, the best mattress for a convertible sofa depends on need and use.