Craig, there are several out there. The first generation are herbal and generate heat when the ingredients are crushed together, much like a cold pack. These are not reuseable. There are reuseable chemical versions available from several camping,surplus and medical supply sites. having said that, Ill have to find them all again.Some of these packs generate enough heat to cause burning, but as your wife will be awake and not in a sleeping bag that is not a concern. There are also battery powered socks;essentially small electric blankets. If the office dress allows for the 'Eddie Bauer' look, those and a knit hat would help.<br><br>