That is the one disadvantage of the Tempur-Pedic beds. They are going to sleep warmer than innerspring or latex mattresses. You can try putting a mattress protector on the mattresss. That will take your body off of the mattress without compromising the support or changing the feel. Tempur-Pedic makes mattress protectors made to work with their mattresses.
I would also stay away from “t-shirt” type sheets that tend to sleep more warm.