In a new study, people age 65 and older who reported trouble sleeping were more likely to commit suicide over the next ten years than those who slept well.

Doctors who treat patients with depression or a history of suicide attempts should consider sleep problems a further warning sign, experts say.

“The majority of individuals who die by suicide visit their doctor in the months preceding, and these are missed opportunities to enhance detection and intervene,” said lead author Rebecca A. Bernert of the Stanford Mood Disorders Center at Stanford University School of Medicine in California.

Sleep can stand alone as a risk factor for death by suicide, even when depression is accounted for, Bernert told Reuters Health, though sleep problems are common for many people who should not be alarmed by this news.

Of the 14,456 people researchers followed over 10 years, 20 died by suicide.

The study team compared the answers those 20 people gave in a series of interviews to questions about symptoms of depression, and mental and physical functioning to the answers of 400 others similar in age, sex and location.

Those who went on to commit suicide tended to rate their sleep poorer at the start of the study than the comparison group, which was true even when researchers took symptoms of clinical depression into account.

With depression accounted for, poor sleep quality was associated with a 20 percent higher risk of death by suicide, Bernert explained. Since only 20 out of nearly 15,000 people in this study died by suicide, even with a 20 percent increase in risk the absolute chance of dying by suicide would still be less than two tenths of one percent.

Globally, suicide accounts for more than half of violent deaths, according to the World Health Organization. And whereas suicide attempts and depression are socially stigmatized, patients usually speak freely about trouble sleeping, since it doesn’t carry that stigma, Bernert said.

Of all the sleep problems described, difficulty falling asleep and not feeling like sleep was restorative were both particularly linked to increased risk of suicide, according to the results in JAMA Psychiatry.

Some experts believe that sleep problems are due to underlying depression, which then increases suicide risk, so the fact that sleep problems were linked in this study to suicide even without symptoms of depression is important, said Wilfred R. Pigeon, who directs the VA Center of Excellence for Suicide Prevention Research and the University of Rochester Sleep Research Lab.

“What is even more interesting is that the risk imparted by poor sleep is even stronger than that imparted by depression,” he told Reuters Health by email.

Having both poor sleep and depression conferred the biggest risk, noted Pigeon, who was not involved in the new study.

In general, not sleeping well causes physical and emotional stress, and could tip the balance for someone with suicidal thoughts, he said.

“Poor sleep is associated with difficulties regulating emotion as well as cognitive deficits, both of which increase the risk of suicidal behaviors,” said Amy Fiske, who researches depression and suicidal behavior in late life at West Virginia University in Morgantown.

“Thus, it is conceivable that sleep problems could lead to suicide by reducing a person's ability to cope with stressors and by impairing their judgment and thinking ability,” said Fiske, who was not part of the new study.

We cannot say that poor sleep causes suicide based on this study, since there could have been factors other than depression that could have caused both disturbed sleep and death by suicide, Fiske told Reuters Health by email.

“Many of us are prepared to say that some sleep disturbances such as insomnia have a causative role in the development of new onset depression, but I don’t think we are there yet with respect to sleep and suicide,” Pigeon said.

Though many other studies have found a similar link between sleep and suicide, most clinicians don’t give sleep problems the weight they deserve, according to Dr. William Vaughn McCall, professor and Case Distinguished Chairman of the Department of Psychiatry and Health Behavior at Georgia Regents University in Augusta.

“We need to continue to increase awareness among doctors,” he told Reuters Health.

Doctors and psychiatrists should recognize that sleep complaints along with depression indicate elevated suicide risk and require treatment, he said. Prescription sleep aids work immediately, but carry risk of dependence and tolerance, and behavioral therapy can work but takes a few weeks to be effective.

Experts agree: the vast majority of older people who suffer from sleep problems are not suicidal.

“We don’t want to create needless panic for older people who are otherwise psychologically healthy and can’t sleep,” McCall said. “For them it’s not time to ring the alarm.”

“If someone has a mental disorder diagnosis, then the additional burden of insomnia should be the warning sign,” he said.

The National Suicide Prevention Lifeline toll-free number, 1-800-273-TALK (273-8255), is available 24/7 and can be used anywhere in the United States.