The findings of 2 studies suggest thatchronic insomnia may trigger and prolongdepression among the elderly population. Thefirst study followed the mental health of >1800men and women over the age of 65 diagnosedwith severe and/or mild depression.Once the researchers determined whether ornot the participants had persistent insomnia,the patients were evaluated twice, first at 6months and then after 1 year, for markers ofdepressive illness.
The results of the study showed that individualswho experienced insomnia were almost 11times more likely to continue being depressedafter 6 months. Furthermore, they were 17times more prone to be depressed after a year,compared with patients without insomnia.
The second study included 147 men andwomen over the age of 60 with no history ofmental illness at the study's onset. Of the participants,34 experienced persistent insomnia, 47had less persistent "indeterminate insomnia,"and 65 had no sleep problems. After conducting2 tests over a 1-year period, the investigatorsdiscovered that 12 patients experienced newonsetdepression during the time frame. Of thenewly depressed patients, half experienced persistentinsomnia, 4 had indeterminate insomnia,and 2 had no sleep problems.
Patients with persistent insomnia and mostat risk for depression were the "middle insomniacs,"characterized by sleep patterns thatwere usually disturbed by waking up in themiddle of the night. The researchers concludedthat patients with persistent insomnia are 6times more likely to exhibit serious new-onsetdepression, compared with individuals whorest easily.