Stephan, thanks for the tips. I am not really sure I get your idea.
How is a metalic sheet under the matress gonna block the EMFs?
I doesn't make sense from an EMF standpoint of view. I know, I have studied theoretical electrodynamics and worked with RF and pulsed HV and MA currents in plasma physics experiments. However, being connected to ground seems to have benefits and although the screen underneath the mattress does not get you in direct contact with the ground, it still seems to have a benefit. The electrical potential (there is hardly any current flowing, maybe in the pA range) seems to do something to the body, that 'repels' bad 'energy'. I have no other way to describe it. Just give it a try. It would be worth knowing if it also helps with EMF. I know, it shouldn't but I have seen and experienced these remarkable results.