consumer advocate for serta pure u.s., elisabeth lemmy says lie down. >> all right.ping position. for me it is my side. you sleep on your back? >> no, no. >> let's be honest. you should really stay put for 15 minutes because consumer reports found the same mattresses that testers liked after a month were the ones they liked after 15 minutes. >> reporter: you don't have to do it for every single mattress in the store, but do take the time for the ones you are really serious about. >> the key is support. you need a good mattress that's going to give you good support. it is not that hard. >> reporter: keith cross owns this place. on to the mattress to know the if it is even a contender. no, no, don't get up yet, don't get up yet. lay down. just roll halfway over. >> reporter: that's something else you need to know. all beds come with at least some foam, and the chemicals used in the manufacturing process can be brutal. lemy says you should look for a bed that comes with foam certified by serta pure u.s.. she is a spokesperson for the nonprofit which keeps track of chemi