Levy reported that in a 2004 study of suburban rail commuters taking the train from New Jersey to Manhattan, «Wener and his coauthor Gary Evans found that the longer their test subjects» journey was, the higher the levels of cortisol (the primary stress hormone) in their saliva, and the more difficult they found to focus on the task of proofreading assigned them at the end of their commute.» (businessinsider.com)
The CLOCK gene has an important role in regulating many rhythmic patterns of the body, including body temperature or level of cortisol, the primary stress hormone. (sciencedaily.com)
The primary stress hormone in your body is cortisol. (mindbodygreen.com)