Insomnia and nightmares, which are often confused and may go hand-in-hand, are known risk factors for suicide but just how they contribute was unknown, said Dr. W. Vaughn McCall, Chair of the Medical College of Georgia Department of Psychiatry and Health Behavior at Georgia Regents University.
The new study reaffirms that link and adds the element of hopelessness about sleep that is independent of other types of hopelessness, such as those regarding personal relationships and careers, said McCall, corresponding author of the study.
"It turns out insomnia can lead to a very specific type of hopelessness and hopelessness by itself is a powerful predictor of suicide," he said.
If the findings hold true in larger studies, they wave a red flag about suicide risk and point toward prevention that targets the negative thoughts with pharmaceuticals and psychological intervention.
The finding also is a reminder to physicians that depressed patients who report increased sleep problems should be asked if they are having suicidal thoughts, McCall said.
The scientists used psychometric testing to objectively assess the mental state of 50 depressed patients age 20-80 being treated as an inpatient, outpatient or in the Emergency Department. More than half had attempted suicide and most were taking an anti-depressant. Testing enabled the researchers to filter out other suicide risks such as depression itself and hone in on the relationship between insomnia and suicide risk, asking specific questions about dysfunctional beliefs about sleep such as: Do you think you will ever sleep again?
"It was this dysfunctional thinking, all these negative thoughts about sleep that was the mediating factor that explained why insomnia was linked to suicide," said McCall, who specializes in depression and sleep disorders.
The likelihood of being suicidal at least doubles with insomnia as a symptom, McCall noted.
The finding appeared in Journal of Clinical Sleep Medicine, the journal of the American Academy of Sleep Medicine.