Insomnia

Insomnia, or sleeplessness, is a sleep disorder in which there is an inability to fall asleep or to stay asleep as long as desired. This sleep disorder is often practically defined as a positive response to either of two questions: “Do you experience difficulty sleeping?” or “Do you have difficulty falling or staying asleep?”

Insomnia is most often thought of as both a medical sign and a symptom that can accompany several sleep, medical, and psychiatric disorders characterized by a persistent difficulty falling asleep and/or staying asleep or sleep of poor quality.

Those who are having trouble sleeping sometimes turn to sleeping pills, which can help when used occasionally but may lead to substance dependence or addiction if used regularly for an extended period.

SYMPTOMS OF INSOMNIA
-Difficulty falling asleep, including difficulty finding a comfortable sleeping position
-Waking during the night and being unable to return to sleep
-Feeling un-refreshed upon waking

TYPES OF INSOMNIA
-Transient Insomnia
Lasts for less than a week. It can be caused by another disorder, by changes in the sleep environment, by timing of sleep, severe depression, or by stress. Its consequences–sleepiness and impaired psycho-motor performance–are similar to those of sleep deprivation.

-Acute Insomnia
The inability to consistently sleep well for a period of less than a month. Insomnia is present when there is difficulty initiating or maintaining sleep or when the sleep that is obtained is non-refreshing or of poor quality. These problems occur despite adequate opportunity and circumstances for sleep and they must result in problems with daytime function. Acute insomnia is also known as short term insomnia or stress related insomnia.

-Chronic Insomnia
Lasts for longer that a month. It can be caused by another disorder, or it can be a primary disorder. People with high levels of stress hormones or shifts in the levels of cytokines are more likely to have chronic insomnia. Its effects can vary according to its causes. They might include muscular fatigue, hallucinations, and/or mental fatigue. Chronic insomnia can cause double vision.

http://en.wikipedia.org/wiki/Insomnia