When children do not outgrow the fears and worries that are typical in young children, or when there are so many fears and worries that they interfere with school, home or play activities, the child may be diagnosed with an anxiety disorder. 

It could be separation anxiety, having extreme fear of  a specific thing or situation; afraid of school and other places where there are people, being worried about the future and about bad things happening.

It may present as fear or worry, but can also make children irritable and angry. Anxiety symptoms can also include trouble sleeping, as well as physical symptoms like fatigue, headaches or stomach-aches.

Some anxious children keep their worries to themselves and, thus, the symptoms can be missed. Hence, professional help is essential to deal with these problems.