The sympathetic nerves are part of the vegetative nerves that primarily regulate the activity of the heart and other internal organs. Under normal conditions, the sympathetic nerve, together with the parasympathetic nerve, which has the opposite function, regulates the balance of the body. Sympathetic nerve activity plays a major role when the body is in a state of tension, quarrels or anger. When the sympathetic nerve is excited, pupils are dilated, heart rate increases, blood pressure rises, bronchial diastole, gastrointestinal peristalsis slows, blood sugar rises, saliva secretion decreases, and so on. Since the body cannot be under tension all the time, the parasympathetic nerves will act to relieve the body’s tension in order to restore the normal situation. The symptoms of insomnia, irritability and irritability are the manifestations of neurasthenia, mainly related to plant nerve dysfunction, so you must develop good habits of life and rest, adjust your emotions, learn to release stress and relax properly.