While insomnia is not a disease but a condition it can have a detrimental effect on children as they are tired and grumpy during the day, often hard for teachers to manage, and this can lead to behavior problems too. If this is something that happens every night then it could be the temperament of the child could be the primary reason. If children know that they can get away with it, they will fight sleep for hours to prove a point.
However, if your child has insomnia that is accompanied with nervousness, irritability, intensity, high strung, excitable, and easily angered then it might be that your child has Attention Deficit Hyperactive Disorder (ADHD). There is a direct relationship between ADHD and insomnia in children. Monitor your child and see if they are extremely difficult to wake in the morning and it is nearly impossible to turn off their motor at night as this too is associated with ADHD.
Children who have insomnia may actually display signs that are very similar to that of ADHD because they are lacking sleep and their systems are out of whack. Children are really supposed to get 9-11 hours of sleep per night, although studies have displayed that is rarely the case. Parents need to remember that children who are exhausted can actually still appear to have so much energy but what that really is, is their body's way of dealing with the tiredness. In the meantime they will become ornery and misbehaved but it is how they are coping with their lack of sleep and you certainly can not expect a good performance academically either.
Some facts about children and sleep are that sleep in one of the most important factors in a child's development because while a child is sleeping is when he body produces more of the hormones that cause children to grow. Children between the ages of one and five require 10-12 hours of sleep per night and school age children require about 10 hours of sleep per night.
So if you have a child that has a difficult time either falling asleep or staying asleep then here are some handy tips to start off with, do not turn on any lights and speak to the child in a very soft voice, and never let a child sleep in bed with you because in no time it will become a repetitive habit. Later that will complicate any insomnia that your child may suffer from so it is important to keep a routine.
source : holistic health articles