“…Harmful effects of stress in humans have been associated with unwelcome life events such as financial and occupational strain, perceived ill health, loss of a spouse or loved one, academic strain, low socioeconomic status, low level of education, military combat, excessive noise, and marital difficulties (50, 55–59, 61, 87, 112). Animal studies have consistently found a depressed immune response in association with noise, isolation, increased population density, male–female proximity, handling by animal keepers, exposure to cold temperatures and deliberate physical trauma (47, 102, 186, 209, 212, 215). In most instances the stressful event was prolonged.…”