is there any medical reason for your body temp. to be less than 90 degrees?

Answer 1

Death. Has rigor mortis set in yet?

Answer 2

your body is hypothermic if it drops below 94 degrees. if you took a bath in ice then yes you will get to the point of 90 degrees but you would die very quickly as your body cant opperate at that low of a tempature. at that low of a temp you wouldnt feel anything. you wouldnt even be shivering anymore, as shivering is the bodies way of generating heat in the muscles. other than that there is no reason your body should ever be that cold