stress may also lead to adaptations, which allow certain organisms to better deal with the stressors. stress happens every day, and is part of every living thing's life. too much stress is bad and can cause health problems. stress plays a part in some physical problems, like heart disease. stress also plays a part in many mental illnesses, like anxiety, acute stress disorder, and ptsd. acute stress disorder and ptsd are mental illnesses that can happen when a person experiences something that is very terrifying, like a major accident or a war. another type of stress disorder is a "psychosomatic illness" where a person has physical symptoms that are caused by an emotional stress, not by physical harm.