I have to concur with brian. I know that whenever I meditate, either in deep theta or QiGong, my body generates an incredible amount of heat. I tend to sweat profusely even when next to an open window in middle of the winter!
The sweating tends to subside farther into the meditation, but to tackle the discomfort, you might want to either wear extremely light clothing or weat a pair of shorts.
Hope this helps.
