Noxious temperature changes and high levels of reactive oxygen species (ROS) have traditionally been regarded as harmful stimuli. However, there is now substantial evidence for the importance of small-to-moderate changes in temperature and ROS levels-well below the thresholds that induce cell death or physiological dysfunction-as fundamental signaling cues that regulate a wide range of physiological functions in mammals. In this review, I summarize our recent findings on the regulatory roles of ...