It is seen in adults as well as children (features varies in both).

Symptoms:

Feeling of excessive anxiety and worry about topic, events or activities.
Excessive worry is experienced as very challenging to control.
Feelings of restlessness, uneasiness.
Feelings of tiredness or fatigue.
Impaired concentration or for kids disturbances in academics.
Irritability.
Increased muscle pain.
Sleep disturbances.