Insomnia is a mental disorder that causes you to not sleep like you should be normally. For some individuals it's only a slight inconvenience but for others it is a very disruptive situation. Insomnia is very common, just about 1 in every 3 adults will show symptoms throughout the world, and 10% of adults do meet criteria for having insomnia. There are two types of categorizing insomnia, time and cause. One of the categories is time can either be acute or chronic which is short time or long time. The other category is cause, cause is whether the insomnia is primary or secondary. Primary insomnia is when it is caused on its own and secondary insomnia is when it's a symptom of a condition and or circumstance.