I find it difficult to drink enough water during winter. I have to remind myself to drink. I use an empty Gatorade bottle filled with water on the kitchen counter to remind me to drink and refill it so I can sort of keep track if I am drinking enough. And, yes, I have heard that before about hydration and cold weather. I've never paid much attention to it as I have always been more concerned with simply staying hydrated because during winter, the cold seems to cool me off even when I am active and I simply don't drink as much even when I should so...but I expect he is correct.
Sleep nekid in your fart sack. Wear layers. Keep your feet dry and clean or the cold will pull out your soul. I drink 100 ounces of water minimum per day. I track everything. The pressing the thumbnail idea was cool. Thanks for that.
Long ago I learned that your head and feet are the main points that keeps you warm or cool. On cold winter night, I sometimes even wear a stocking hat to bed. A hat is the first thing I take off if I am too hot and the first thing I put on if I'm too cold. Feet if wet or cold will make the rest of you cold so keep them dry and warm.