Older adults who complain of poor sleep quality, independent of a depressed mood, are at increased risk for suicide, says a study.
Two sleep factors in particular - difficulty falling asleep and non-restorative sleep - were associated with increased suicide risk.
"We suggest that poor subjective sleep quality may, therefore, represent a useful screening tool and a novel therapeutic target for suicide prevention in late life," said Rebecca Bernert from Stanford University School of Medicine in the US.
Suicide is a preventable public health problem and accounts for almost 1 million deaths annually worldwide.
The study sample included 420 individuals (400 control patients and 20 patients who committed suicide) who were selected from 14,456 participants.
The researchers examined the risk for suicide associated with poor reported sleep in a group of older adults (with an average age of nearly 75 years) during a 10-year observation period.
Those individuals who reported poorer sleep quality at baseline had a 1.4 times increased risk for suicide.
When the researchers controlled for the effects of a depressed mood, people with poorer sleep at baseline still demonstrated a 1.2 times greater risk for suicide during the 10-year observation period.
The study appeared online in the journal JAMA Psychiatry.