What about this trick?
Instead of using an electric blanket to pre-warm your bed, use an electric iron. Yep, thats's right!!!
In the winter, I usually have a thick down comforter on my bed. On cold days, I heat up the iron, unplug it, take it to the bedroom, pull down the comforter and "iron" the premade bedsheets. I concentrate on the foot area and pull the comforter back on. It will stay nice and warm usually for an hour or more. When i get ready for bed, its still nice and toasty!
I am willing to bet that the hot iron probably kills a few dust mites in the process!
Try it.