The stress response in children represents an opportunity to teach healthy, adaptive coping strategies. Responding to stress is different than reacting to it. A stress reaction is when a child encounters a combination of internal and external stressors that trigger stressful reactions. The latter is usually automatic and based on habits of the past. A response, such as a mindful one, is a healthy proactive positive approach and alternative to reacting.
In young children this stress reaction can be a "melt down," a tantrum, or emotional dysregulation. In middle school aged or teenage children, it presents as sadness, anger, depression, and certainly anxiety. The automatic habit-based stress reactions are less healthy and we know this from a physiological perspective as studies have proved the effect stress reactions have on the heart, the brain, the circulatory system, pain management, etc.