April 2008 - A long-term study of almost 600 young adults found that those with annual one-month periods of insomnia found the incidents of sleeplessness gradually increased over two decades, especially among women. In 40 percent of subjects, insomnia developed into more chronic forms over time, according to findings published in the April 1 issue of Sleep.

Insomnia lasting two weeks or longer predicted major depressive episodes and disorders, according to the report. Seventeen percent to 50 percent of subjects with insomnia lasting two weeks or longer later developed a major depressive episode.

"The results show that insomnia seems to be followed by depression more consistently than the other way around. In addition, we found that insomnia tended to be a chronic problem that gets more persistent over time, whereas depression was a more intermittent problem," accrding to study author Dr. Daniel J. Buysse, of the University of Pittsburgh.

"We used to think that insomnia was most often just a symptom of depression. However, a growing body of evidence suggests that insomnia is not just a symptom of depression, but that it may actually precede depression. In other words, people who have insomnia but no depression are at increased risk for later developing depression," Buysee said.

About Insomnia

Insomnia, the most common of all sleep disorders, is when a person has trouble falling asleep, staying asleep or waking up too early. About 30 percent of adults have symptoms of insomnia.