This varies. Most often nothing, which is less fetching as I age but still comfy. If the house is cold and I'm watching heating dollars, it can be a long sweatshirt.
I do have one flannel gown with a hood (a hood? well, I liked it and bought it) and long sleeves and crescent moons all over it that I drag on once in a while. I happen to have a lot of blankies.. well, that is, a few that I can pile up to warm the bod. The deal is getting up in the morning with the low temp, and leaving my blankies.