Typically it is said when listening to someone talking-- it is a polite way to let them know that you are paying attention. Think of it as going 'mm' or 'ah'.
In addition stress can have direct effects on the skin (rashes, hives, atopic dermatitis, the gastrointestinal system (GERD, peptic ulcer, irritable bowel syndrome, ulcerative colitis) and can contribute to insomnia and degenerative neurological disorders like Parkinsonâs disease.
Extreme Trauma and PTSD. 1  PTSD may develop following exposure to extreme trauma. 2  The stress caused by trauma can affect all aspects of a personâs life including mental, emotional, and physical well-being. 3  Research suggests that prolonged trauma may disrupt and alter brain chemistry.