While insomnia can be classified as a symptom of mental illness, recent research appearing in the April issue of the journal Sleep provides evidence that in many cases, insomnia, which refers to problems falling asleep, staying asleep, or waking up early, is an independent disorder often occurring alongside other forms of mental illness. In examining the the relationship between depression and insomnia in adults aged 60 years or older, a team of researchers found an association between persistent insomnia and chronic depression.
The researchers, led by Dr. Wilfred Pigeon of the University of Rochester Medical Center, used data from a previous study of Project Impact (Improving Mood-Promoting Access to Collaborative Treatment), a program designed to aid older adults seeking treatment for depression. The program centers on collaborative care involving the individual's physician and other mental health professionals who provide information, counseling, monitoring, and who can adapt the treatment program to the individual's needs. The current study's 1,801 subjects were assigned either to the IMPACT program or to receive the usual depression treatment offered by their health clinic. Using assessments made at baseline and three months, the researchers placed the subjects into three groups based on their insomnia symptoms: those with persistent insomnia, those with intermediate insomnia, and those without insomnia. The subjects received further evaluations after six and 12 months.
After controlling for depression severity and other coexisting illnesses, the researchers found that compared with subjects who did not have insomnia, those with persistent insomnia were 2.8 to 3.5 times more likely to have significant symptoms of depression after six and 12 months. The prevalence of depression also increased according to insomnia severity, so that the rate of depression at six and 12 months was higher among those with intermediate insomnia than those without insomnia and higher in those with persistent insomnia than those in the intermediate group. These results were strongest among those not involved in the IMPACT program, and the researchers suggest that a more intensive treatment program may be needed to improve the symptoms of depression and insomnia in some individuals.
Research continues to inform our views of insomnia and depression, and other recent research has supported the concept of insomnia as more than just a symptom of other mental disorders. In studying nearly 600 individuals over the course of 20 years, researchers from Switzerland demonstrated that insomnia often precedes depression and may boost an individual's risk of developing the latter. However, as Dr. Pigeon notes in his study, the relationship between insomnia and depression may be complex, varying from person to person. Insomnia could be a symptom of depression in many cases, but in other instances it is most likely an independent disorder contributing to the subsequent development of depression or worsening the symptoms of existing depression.
While Dr. Pigeon's study was not designed to examine which disorder developed first or why the link between these two disorders occurred, the study's results suggest that insomnia may complicate depression treatment in some cases or act as a barrier to recovery, contributing to a lengthier illness. Insomnia may also be an indication of more severe or treatment-resistant depression. And, as this study focused exclusively on an older sample, these results may only be true in older adults. For individuals with both depression and insomnia, addressing both conditions is important, and further research on the relationship between these two disorders may point toward the most effective forms of treatment.
|