Appreciation is appreciated, and I can only wish much [low-voltage] warmth to all PALS this winter.
One tip while I am here: these pads are a pain to wash (separately, instructions require clock-watching) and will never completely shed stains, so a mattress protector between this and the bottom sheet is highly advised.
If you have an overlay, put it on top of the heated pad and then a protector between the sheet and the overlay.
Don't worry, the heat will penetrate whatever layers you have on top of it, as long as it's on top of the mattress. Also, I can't remember if the description on line says something about adjustable beds (for legal reasons it might), but it's fine w/ any bed position once it is in place.