Hi valli,
While bedding is not my area of expertise … you can read a little more about silk mattress pads or toppers in post #2 here and in post #10 here and the links they include. Like wool silk is very good at controlling humidity and the sleeping microclimate and can regulate temperature in both directions.
There’s also an interesting video here about layered mulberry silk (as opposed to silk fleece) even though it’s more about comforters than toppers.
Post #6 here has a brief comment about wool and silk from one of the members here who is one of the most knowledgeable experts on bedding materials that I know.
Phoenix