Heat escapes through the feet.
This is the first time in my adult life that this fact has been relevant. I got through entire Minnesota and New England winters without ever donning socks thicker than those I wear year-round. (My concession to the weather was my stomping boots, which are a good, thick leather.) On Monday, I was wearing over-the-knee regular sock-weight socks, instead of the lightweight trouser socks I normally wear (same weight as average tights), and I was comfortably warm. On Tuesday, I was wearing tights and no extra sock-layers, and I was not freezing, but cold enough to be very, very glad I keep a pashmina shawl at work. Today, I am wearing tights under warm, cashmere-blend knee-high socks. I had to take my fairly light-weight cotton sweater off when I got to my desk. I'm going to need to put it back on when other people start arriving, as a strappy camisole isn't terribly professional all by itself, but I am waiting until then. So yeah, socks. I need to start wearing socks. I don't have very many of those. So, if anyone is wondering what to get me for my birthday or Christmas, it appears I need more socks. I prefer knee- or over-the-knee length, as I need a layer of fabric between my skin and my braces.
If only I knew somewhere to get awesome socks.