According to youth.gov, a national and international literature review found that an average of 17 percent of young people experience an emotional, mental, or behavioral disorder.  Warning Signs Marked decline in school performance Poor grades in school despite trying very hard Severe worry or anxiety, as shown by regular refusal to go to school, go to sleep or take part in activities that are normal for the child's age Frequent physical complaints Marked changes in sleeping and/or eating habits Extreme difficulties in concentrating that get in the way at school or at home Sexual acting out Depression shown by sustained, prolonged negative mood and attitude, often accompanied by poor appetite, difficulty sleeping or thoughts of death Severe mood swings Strong worries or anxieties that get in the way of daily life, such as at school or socializing Repeated use of alcohol and/or drugs