Wikipedia - Insomnia
Wikipedia's article on insomnia.
Chronic Insomnia: A Practical Review
American Insomnia Association
The American Insomnia Association (AIA) is a patient-based organization that is dedicated to assisting and providing resources to individuals who suffer from insomnia. The AIA advocates and promotes awareness, education, and research of insomnia disorders and encourages the formation of local support groups.
20 Ways to Wake Up Alert, Rested and Refreshed. By Thomas Yarnell, Ph.D.
In-depth article on causes, clinical information, and possible treatments.