<p>It's important to recognize and treat mental illnesses in children early on. Once mental illness develops, it becomes a regular part of your child's behavior. This makes it more difficult to treat.</p> <p>But it's not always easy to know when your child has a serious problem. Everyday stresses can cause changes in your child's behavior. For example, getting a new brother or sister or going to a new school may cause a child to temporarily act out. Warning signs that it might be a more serious problem include:</p><ul> <li>Problems in more than one setting (at school, at home, with peers)</li> <li>Changes in appetite or sleep</li> <li>Social withdrawal or fear of things he or she did not used to be not afraid of</li> <li>Returning to behaviors more common in younger children, such as bedwetting</li> <li>Signs of being upset, such as sadness or tearfulness</li> <li>Signs of self-destructive behavior, such as head-banging or suddenly getting hurt often</li> <li>Repeated thoughts of death</li> </ul> <p>To diagnose mental health problems, the doctor or mental health specialist looks at your child's signs and symptoms, medical history, and family history. Treatments include medicines and talk therapy.</p> <p class="">NIH: National Institute of Mental Health</p>