just be honest with him, tell him you cant afford to keep the temperature that high at night, but if he wants to keep it that high he will have to pay the extra cost of the electric bill.
if he`s cold give him another blanket and a sweater.
Have you ever given a pretty good answer, and then
after you got a lot of thumbs up for it, you change it to a really rude and obnoxious answer so that it looks like people gave a thumbs up to the rude and obnoxious answer?