When temperatures plunge, and white, fluffy stuff insists on falling out of the sky daily; when your bones rattle and teeth chatter because -- baby it's cold outside -- then it's time to curl up in bed and get warm. An electric blanket will do the trick within minutes, but if you feel guilty about leaving a carbon footprint, consider alternative blankets that will have you warm as toast.
First, the Science
What is it about some blankets that barely keep you warm, and others that you kick off during the night because of the heat they give? Actually, it's not the blanket that's producing the heat; it's your body. The blanket merely traps that heat; the fibers conduct, or don't conduct it. Flat fibers like those found in synthetic blankets don't trap the warm body heat. Curly wool fibers create air pockets for the warm air to nest in, as do the pockets of air surrounding clumps of down, returning that warmth to swim over your body.
Less is more. We're talking about down here -- those lightweight bits of fluff plucked from birds and used to fill blankets, jackets and coats. The fill power denotes the volume of a single ounce of down. A high fill power comes from the down of a mature bird, and while it insulates best, it weighs less. But if it can keep the birds warm, you'll do just fine. Clusters of down from mature wild geese are larger and warmer than those plucked from farmed ducks. The lower the fill-power count, the lighter the blanket and the less warmth you'll get.
100 Percent Wool
If the blanket is 100 percent merino or alpaca wool, then it'll keep you warm. Merino wool comes from merino sheep, a breed with fleece that's made for extreme temperatures. One of its unique factors is that it draws perspiration away from the body. It's also antimicrobial and hypoallergenic. Alpaca wool is also very warm, and because it contains no lanolin, it too is hypoallergenic. The softness of alpaca wool equals that of merino, and neither of which are scratchy like the wool blankets you may have grown up with.
Fleece is a synthetic material designed to mimic the properties of wool. It has a variety of names, including polar and micro fleece. Both are used in blankets and are lighter than wool. A dissection of fleece reveals that it's woven to incorporate pockets of air, trapping warmth, just as do the curly fibers of wool. Look for a fleece that is anti-pill, a more expensive but more attractive blanket that doesn't need a shave after several uses.
Mylar Space Blankets
A metalized film over an aluminum-based sheet is a product of America's Space Age; a research scientist discovered that covering and keeping a satellite warm also works to keep people warm. Body heat is reflected from the sheet back to the body when it's used as a blanket. Put your space blanket over a wimpy blanket and sleep snugly through the long and cold winter night.