Elderly patients who report poor sleep quality face a significantly increased risk of suicide for up to a decade, whether or not depression is also present.
Even after controlling for comorbid depression, investigators found that impaired sleep was associated with a 20% increased risk of suicide in these patients.
Results of the prospective observational study suggest that regularly asking about sleep quality might help improve suicide risk assessment, Rebecca A. Bernert, Ph.D., and her colleagues reported online Aug. 13 in JAMA Psychiatry (doi: 10.1001/jamapsychiatry.2014.1126).
Older adults tend to seek more physician care in the final weeks and months before a suicide than do other at-risk populations (73% and 45%, respectively).
"Furthermore, at least one psychological autopsy study indicates that disturbed sleep is visible to friends and family members in the weeks and months preceding death," wrote Dr. Bernert of Stanford (Calif.) University and her coauthors. "Targeting disturbed sleep as a visible warning sign of suicide may, in this way, constitute a novel opportunity for improved risk detection; this more narrowed, demographic focus may specifically inform intervention among a group at heightened risk for suicide."
The cohort comprised 420 subjects who were a subpopulation of the Established Populations for Epidemiologic Studies of the Elderly study. This project followed 14,500 older adults from 1981 to 1993; its purpose was to identify predictors of mortality, hospitalization, and placement in long-term care facilities and to investigate risk factors for chronic diseases and loss of function.
From this group, 400 controls were matched to 20 subjects who had committed suicide.
Sleep was evaluated with a five-item Sleep Quality Index (SQI) constructed by the investigators. Other measures included assessments of depression, cognition, and physical function.
Subjects were a mean of 75 years old at baseline; 60% were white, 19% were African American, and 1% were Asian, American Indian, or Hispanic. The methods of suicide included firearm (62%), cutting (10%), hanging (9%), poisoning (5%), drowning (5%), lethal jump (5%), and suffocation (5%).
The mean SQI scores were significantly higher among those who committed suicide than among the controls (10 vs. 8). Individuals who committed suicide also reported higher scores on all of the SQI subsets: difficulty falling asleep, difficulty staying asleep, early morning awakening, daytime sleepiness, and nonrestorative sleep.
In the univariate analysis, the total sleep score was a significant predictor of suicide (higher score odds ratio, 1.39) over the 10-year follow-up period. Difficulty falling asleep and nonrestorative sleep also were significant predictors (OR, 2.24 and 2.17, respectively).
After controlling for the presence of baseline comorbid depression, the investigators found that the relationship between overall sleep quality and suicide remained significant (OR, 1.2). Difficulty falling asleep and nonrestorative sleep lost their significance in the multivariate analysis.
The authors proposed that sleep-related deficits in cognitive and emotional processing might be a key factor in suicide among such patients.
"Research indicates that sleep fragmentation results in increased emotional reactivity, intensifying negative emotional responses while blunting positive affect," they noted. "Similarly, sleep deprivation among healthy adults is associated with amplification of amygdala activation, as well as increased reactivity to negative emotions such as anger and fear. Notably, a night of recovery sleep following sleep deprivation reverses this effect, decreasing amygdala activation and reducing such emotional reactivity.
"We propose that such deficits may lower the threshold for suicidal behaviors by impairing the processing of emotionally salient information and associated neural circuitry."
The authors cited several limitations of their study. For example, the measures of sleep quality were self-reported rather than measured objectively. Also, diagnostic information that might influence sleep quality, such as chronic pain and substance use, was not included. Finally, the results are not generalizable to the larger population because 19 of the 20 decedents in the current study were male. "Although this reflects national rates and statistics, the present results should be interpreted as primarily applicable to men and chiefly white men," Dr. Bernert and her associates wrote.
The study was sponsored by the National Institutes of Health and the Centers for Disease Control and Prevention. Neither Dr. Bernert nor her coauthors reported any financial conflicts.