I was recently informed that it is apparently not reasonable to keep the bedroom thermostat set at 45ºF (7ºC) in the winter— to which I could only retort, "But it's the best!" Blame my Norwegian heritage, but I can only sleep well in the cold.
Here's my ideal bedtime situation: approximately 40ºF, with the windows open and a light breeze blowing through the nearly-empty bedroom, near-perfect silence, deep dark, three down pillows of various levels of fluff, medium-firmness pillow-topped mattress, freshly laundered cotton sheets, no pyjamas, a massively fluffy down comforter (or two or three), and a bedside lamp so I can read a book for a while before drifting off.
I lived in San Francisco for eight years and only once did the temperature get down to freezing. I had all of my windows open that night as usual, and it was the best night sleep I'd had in forever. Now that I live in the Midwest, early spring and late fall are the best because I can keep the bedroom cold without endangering all of the pipes and such— something you have to worry about when it's -20ºF. (I sincerely do not mean any disregard for all of the people struggling to heat their home, and know how insanely lucky I am to be able to afford heat and blankets.)
If you could design the ultimate sleeping chamber for yourself, what would it involve? A big television? Twenty pounds of blankets under the stars? A dozen cats snoozing on top of you?