The art & science of asking questions is the the source of all knowledge" - Thomas Berger

When I toss and turn, the mattress there is a squeaking sound from the bed. What is that? And how to resolve it?

There are a few possibilities to the squeaking sound.  First it might be the friction between the base of the mattress and the supporting base of your bedframe.  All you need to do is to put a sheet of cloth in between them.  Alternatively, you may spread some baby powder on the supporting base of the bedframe before you place the mattress on it.  The second possibility might be the mattress are placed too close to a wall or cabinet which create the friction.  You just need to ensure there is a gap between them so that friction does not occur.  The next possibility might be the bedframe support structure having some problem or the mattress spring itself having an issue.  If you are unable to resolve the squeaking sound after trying out the above methods, you may call us for us to do a site inspection.