Anyone who suffers from chronic insomnia, as I do, may find this analysis of the research and literature informative. It's a bit technical, so it may put you to sleep, but that's a good thing!
http://www.ahrq.gov/clinic/epcsums/insomnsum.pdf
"Manifestations and Management of Chronic Insomnia in Adults" (PDF; 496 KB)
"There is evidence that chronic insomnia is associated with older age, female gender, present or past psychiatric illness and psychological problems, medical conditions and poor general health, increased healthcare utilization, lower quality of life and social relationships, socioeconomic status (marital separation, unemployment, poorer working conditions and lower social status), and decrements in memory, mood, and cognitive function."