How to keep your bed warm.

[MGfromBC]

I've mixed and matched from most of the things already mentioned. Another thing I've been known to do is make a thermos of very hot coffee to toss in the bottom of the sleeping bag. As far as heat goes, it's sort of slow release, but it's still hot coffee in the morning.

 

[BelgianPup]

Make a bivy (bivouac -- like a pup tent) over the bed to trap body heat. A rope or length of PVC pipe can hold it above you.