I had my shower as normal. When I'd finished, I turned the on/off knob and got out as normal. This morning, my boyfriend asked me if I'd had a cold shower last night. I said no, and asked why. He said that when he got in the shower it was freezing cold. He realised why. The temperature knob had been turned to cold. Now, in order to go from hot to cold, you have to turn the knob from right to left, about 180 degrees (a half circle). It sticks in the middle a bit, so you have to give it a hard tug to shift it. There's no way I could have caught the knob accidentally, partly because of how hard it is to move it all the way across, and partly because there's about an 8 inch gap between the two knobs.
Can anyone please think of a rational explanation for this? Because at the moment the only thing I can think of is that I'm going mad and turned the knob without having any recollection of doing it. Or sleepwalking, which is something I never do.