Originally Posted by
Wogsterca
Cheapest is to invest in a toque, this is a knitted hat, usually wool (or synthetic wool), and a few are thinsulate lined. Most sleeping bags, either don't have a hood or have an uninsulated hood, unless you get into the really cold weather bags. Adding a little insulation with a toque ( you pronounce that as too-ck), it's actually the French name although it's used in English Canada as well. In the US, you probably hear the term in Northern border States, although watch cap is probably common as well along the seaboards. You often will not see me outside between December and March without one on. Should add a good 2-3 degrees to the temperature rating of a bag.
Another option, get a sleeping bag liner, liners can be good at any time, in that it has the advantage of keeping the inside of the bag clean, when it gets grungy, toss it in the wash. Another option, is to wear clothes when sleeping, this is best when you have cold spots.
Good suggestion about the "toque" (new word for me...I'll try to use it in a sentence three times before bedtime).
I surmise that a sleeping bag liner (see them made of natural, breathable materials such as silk) may be different than a vapor barrier liner, eh? (See. I speak a bit of Canadian). Still makes me claustrophobic just discussing them.