Spanish langage version of Sleepdex - Recursos para Dormir Mejor
Eric E. Chudler's sleep page - explanation of neuroscience of sleep from a professor at Washington University
The Cleveland Clinic has a good website section on parasomnias.
New Science magazine's instant expert on sleep.
Comparing Newer Drugs for Insomnia - from the National Center of Biotechnology Information
Restless Legs Foundation - affiliated with the Mayo Clinic
University of Pennsylvania Center for Sleep and Circadian Neurobiology
Journal of Clinical Sleep Medicine - archives of abstracts
American Academy of Sleep Medicine - a professional organization dedicated to sleep medicine and research.
American Sleep Apnea Association - non-profit organization dedicated to reducing injury, disability, and death from sleep apnea and to enhancing the well-being of those affected by this common disorder
National Center on Sleep Disorders Research - federal government's website contains substantial information on sleep
The UK's National Health Service Self Help Leaflets - there's one on sleeping problems
What is Sleep Apnea - From the National Heart, Lung, and Blood Institute
M.D. Anderson Sleep Center - clinic that studies and treats cancer patients with sleep problems
Alzheimer's Association - Sleep and Alzheimer's
Sleep and Cancer - National Cancer Institute
Sleeping Well - from the Royal College of Psychiatrists