On top of insomnia, what other sleeping disorders exist?

Many sleep disorders: Including disorders of initiating & maintaining sleep, excessive sleep, disorders of the sleep-wake cycle, sleep apnea, night terrors & nightmares, sleep walking, & disorders related to sleep -- enuresis, bruxism, restless leg. Many internet resources, e.g., www.Nlm.Nih.Gov/medlineplus/sleepdisorders.Html.

Chemical interaction: and disbalance of neurotransmitters in the brain known to initiate either sleep or wakefulness may interfere with sleep. Some patients just have an individual/specific biochemical setting of their central nervous system, predisposing them to insomnia. In those cases, multiple approaches, medications, and/or procedures remain of low efficacy, as a symptomatic treatment.