IR film is sensitive to shortwave IR, i.e. under 1um. Stuff isn't going to show up brighter on the film unless it's at a few hundred degrees, i.e. just short of glowing - if the film were sensitive to longer-wave IR emitted by things at body temperature then just allowing the film to come to room temperature would expose it; it would need to be kept practically frozen from manufacture, while being used and while being developed.

The usual pictorial use of IR is to photograph people and foliage in full sun - google for the "Woods Effect" and/or look for images tagged with HIE on flickr. You will need a special filter, e.g. an R72.