Depression in childhood and adolescence

Major depressive disorder, often simply referred to as depression, is a mental disorder characterized by prolonged unhappiness or irritability. It is accompanied by a constellation of somatic and cognitive signs and symptoms such as fatigue, apathy, sleep problems, loss of appetite, loss of engagement, low self-regard/worthlessness, difficulty concentrating or indecisiveness, or recurrent thoughts of death or suicide.

Source: Wikipedia — Depression in childhood and adolescence (CC BY-SA 4.0)