22 June 2005

Relationship Between Insomnia And Depression Revealed

by Kate Melville

Not being able to get a good night's sleep is torment enough without being told that insomnia can both cause and prolong clinical depression. There's no good news to be had in two new studies that show insomnia, far from being a symptom or side effect of depression, may instead precede it, making some patients more likely to become and remain mentally ill. The papers will be published in the Journal of Behavioral Sleep Medicine.

For some time researchers have thought that insomnia and depression were linked, but struggled to establish what the relationship was. The consensus among experts was, until recently, that depression caused insomnia. But along with new drugs designed to treat depression, came the realization that improving depression did not alleviate insomnia. Going against conventional wisdom, the idea that insomnia could be a contributor to, or predictor of, depression gained credence.

The studies run through a list of groups most at risk of depression and who also suffer with poor sleeping patterns. Compared to those who do not experience depression, it is elderly patients with insomnia (and no history of depression) who are 6 times more likely to experience an initial episode of depression. The elderly in general are a high-risk group, because two million older adults have a depressive illness, and five million more experience less severe forms of depression. As a group, they account for 18 percent of all suicide deaths despite representing just 13 percent of the population.

What many might find most alarming about the two studies is that those people most at risk of first-time depression are patients with severe "middle insomnia," where patients wake up frequently during the night, but eventually fall back to sleep each time. This description of inadequate sleep patterns probably account for nearly everyone at some stage of their lives. Michael Perlis, director of the University of Rochester Sleep Research Laboratory, said that: "The new findings are especially significant because they suggest that targeted treatment for insomnia will increase the likelihood and speed of recovery from depression." Now that the connection between insomnia and depression has finally been made, subsequent trials and studies are being conducted into improving sleep patterns.

Source: Media release - University of Rochester Medical Center