Someone keeps turning my fan off...

The weather remains a little on the cool side, but that has not stopped me from going to bed sweating and a little on the warm side. Sometimes I even notice sweating when I get up to go to the bathroom during the night.  Now, I've thought my body's temperature sensing and control mechanisms were out of whack since last summer, although the extremely cold winter may have alleviated this problem some what. 

Because these sensations are unpleasant, I've started sleeping with the fan on at night.  Lately, however, the fan has been turned off when I wake up in the morning. I am not usually sure why this is, unless I know I turned it off the night before.  The housemate, the only other person in the house, swears she's not doing it. 

I have come up with multiple theories, all of them of which I find equally likely:

1.) I am simply forgetting that I turned it off.
2.) The housemate is lying about not turning it off
3.) Friendly energy-saving spirits turn the fan off to prevent the electrical bill from becoming too high. (I love the possibility of gnome intervention.)
4.)  My parasomnias have reached a new level that now allow me to manipulate switches and knobs in my sleep.