Following a trauma, some people may develop an acute reaction to seeing or experiencing a frightening event. The person's age will affect how the event is experienced. For example, a young child may refuse to go to school and become more "clingy" in behavior. An adolescent may become more argumentative while minimizing her/his concerns. Adults may withdraw, express feeling "numb" or in "shock" and become preoccupied with the events of the trauma. Common reactions include disbelief, denial, anxiety, relief, grief, hostility, and altruism. Somatic problems such as loss of appetite, headaches, and sleep disturbances are commonly observed. Some of these reactions may take weeks, and possibly months, to appear.