From a Google search I found this info: http://www.truthforhealthyliving.org/testrelat.htm
Communications and relationships that work (at work and elsewhere) involve interactions between people who are experiencing comfortable emotions and physical states. An uncomfortable emotional state such as anger with an uncomfortable physical state like a “tension headache” discourage getting along. The most direct cause of such discomfort is psychological stress: the biochemical response to an unknown perception of threat. To the point, the more stress you have the more your relationships suffer. The more your relationships or interpersonal communications are hurting, the greater the likelihood you will have even more stress.