For something as critical to our well being as good sleep, human beings suffer from an amazing number of sleeping disorders. The following Web sites explore just a few of these disorders, starting with a brief introduction to the normal stages of sleep from the Sleep Disorders Center of Central Texas (1). Next, the University of Waterloo offers a fascinating look at sleep paralysis, which many researchers consider the "likely source of beliefs concerning not only alien abductions, but all manner of beliefs in alternative realities and otherworldly creatures" (2). The third site (3), provided by the National Women's Health Information Center, is an easy-to-read source for information about insomnia. Likewise, the American Sleep Apnea Association (ASAA) offers an in-depth information packet on snoring and sleep apnea, as well as the ASAA newsletter and other resources (4). The next Web site (5 ) comes from the National Institute of Neurological Disorders and Stroke, and offers an introduction to the phenomenon of narcolepsy, including treatment, prognosis, and related research. Restless legs syndrome may not be as immediately familiar as some of the other sleep disorders addressed above, but a visit to the homepage of the Restless Legs Syndrome Foundation (6) should answer any questions about this "creepy-crawly" sensation in the limbs that occurs during sleep or other inactive periods. Of course, you don't have to have a bona fide sleeping disorder to suffer from sleep deprivation. Visitors to the next Web site from Loughborough University's Sleep Research Centre will find detailed information on how sleep deprivation affects brain function (7). Not surprisingly, the news isn't good. Finally, the Sleep Foundation offers How's Your Sleep, an online quiz designed to help users learn more about what may be affecting their sleep (8).