I'm opposite of Erika. I have to have the heat up to 72 at least, at night, to help with jerking of my limbs and back. If I am too cold they jerk more. And of course I cannot wear any nighties any more because of itchy skin from Polycythemia Vera (have not found a fabric which works at night, although I do have ones which work by day). I usually sleep with the covers pulled way down, and the heat up.
This does not mean I like summer heat! I'm comfy at 72 but when it goes up to the real summer heat, like over 80 or 90, it isn't good.
The itch is driving me nuts at night--I often have to get up and drink more water or tea and watch something on the computer, because it distracts from the itch. People with PV usually have this itch and it is a major major symptom, hard to deal with, even with tons of body cream. I use only the purest body cream from the Health Store, read all labels.
It is exacerbated by the very very dry climate here, the dangerous drought we are in. Even an excellent humidifier does not do the whole job.