There are four main causes of insomnia and they can be broken down into categories. Symptoms of insomnia present themselves in a variety of forms from the complete inability to fall asleep to waking up too early every morning or feeling tired after what would ordinarily been a sufficient amout of sleep. While there is no cure for insomnia, there certainly are some very effective insomnia remedies.

The first main cause of insomnia is psychological:

This is usually the result of the mental baggage we carry with us to bed. Relationship problems are a common cause as they would often weigh heavy on our minds while we try to fall asleep.
Stress which affects almost all aspects of our health, certainly plays a major role in our sleeping patterns. Whether it is work related stress, or even family or finance related stress, it is very likely to interrupt restful sleep.

The second cause of insomnia is psychiatric:

The most common form cause of insomnia in this category is depression. Depression is a very serious condition and when insomnia is added to the mix, a person can literally lose the will to live.
An overactive mind is another factor. A perfect example of this is when a person has a big day ahead of them, they often battle to fall asleep in anticipation of the day ahead. Many people are more alert at night and as a result battle to fall asleep easily at the best of times. Add stress to this and it is very easy to become an insomniac.

The third cause of insomnia is Psysiological:

These would include things like noise or light interruptions. An uncomfortable bed or pillows is a common culprit. Even a snoring partner or a blocked nose can be the cause of insomnia.
Light is a very important factor. When the room is dark and we are in a sleep the brain will produce Melatonin. Light interferes with the production of this compound which in turn affects our sleep-wake up cycle.

The fourth cause of insomnia is Pharmacological:

Both over the counter and prescription medications have been known to cause insomnia or to disturb regular sleeping patterns. Often it is one of the things people least expect to be the cause. Anti depressants and even blood pressure medication have been found to be a cause insomnia in some cases. Alcohol and narcotics are very well documented causes of irregularity in sleeping patterns.