Hi,
I am not sure how much those grounding sheets are. They seem to really help some people and others don't feel so well. I'm thinking that the best thing is do it naturally on the ground.
That is where I felt my results from (haven't tried the sheets yet). I would not use a mattress , I think a blanket is sufficient. That is what I used. Since my last post I have been laying outside on the ground and noticed just now when I came back in that I was able to get up my stairs with no problem. I usually struggle going up my stairs because I'm so weak and hurt. I did feel a little stimulated the first 30 minutes but it went away.