“Most researchers on temperament have studied short-term arousal. It’s easy to study, for it’s quite apparent from the higher levels of heartbeat, respiration, perspiration, pupil dilation, and adrenaline. There is another system of arousal, however, that is governed more by hormones. It goes into action just as quickly, but the effect of its main product, cortisol, is most noticeable after ten to twenty minutes. An important point is that when cortisol is present, the short-term arousal response is also even more likely. That is, this long-term type of arousal makes us even more excitable, more sensitive, than before.”