When a person experiences fear, adrenaline and stress hormone, cortisol are released into the blood and reactions like fast heart beat, rise in blood pressure, dilation of pupils and increased sweating occur.

Fear can be caused by many factors. For example, some people are afraid of spiders. Similarly there is the fear of blood, fear of exams, fear of height and many more. Children are generally afraid of darkness and this fear reduces with age. The fear of separation from parents is also quite high in children.