We all have secret fears which may sound silly to others but are very real to us. It's only when these fears become major phobias that damage our day to day lives that we need help.
Children have different worries at different ages. A three year old might be terrified by sirens and dogs. By their early teens they worry about looking foolish and how they appear.
Miscommunication also raises fears. When a grandad is rushed to hospital it might easier to say he has a bad cold than explain heart failure. But if grandad dies in hospital, the child's next cold might be seen as a serious event.
I have worked with children who have a fear of walking around the house alone at night. Reassurance is an important role for parents. We can support children through their fear by holding their hand through a dark room and standing near by as they go alone. Desensitisation, especially if carried out gradually and in a relaxing manner, is an effective strategy. For example if the dark is a problem, keep the lights on dim until confidence starts to grow.
As a psychologist, I believe that helping parents and children by encouraging honest communication, giving reassurance, and using desensitising and relaxation strategies, is much better than psycho-analysing children.