Suicide rates have been rising alarmingly in the U.S. and have reached a 30-year peak of 13 per 100,000 people, according to a 2016 report by the U.S. Centers for Disease Control and Prevention. As psychologists and public health officials scramble to find solutions, Michael Nadorff, a psychologist at Mississippi State University, argues that one treatable risk factor has been hiding in the dark: nightmares.

Over the past five years Nadorff's research has shown that nightmares are an important clue to suicide risk among healthy individuals—and that therapy aimed at addressing their nightmares could help save lives.

Scientists measure suicide risk by three elements: thoughts of suicide, suicidal behaviors and individuals' own beliefs about the likelihood that they will die by suicide. In a 2011 study published in the journal Sleep, Nadorff and his colleagues evaluated suicide risk in 583 undergraduates and then examined how symptoms such as anxiety, depression and nightmares were related to that risk. Not surprisingly, the researchers found that the more severe the symptoms, the higher the suicide risk. When they looked more closely, however, they found that having nightmares correlated with overall suicide risk more closely than any other factor.

“What amazed me was that not only are nightmares associated with suicide but the relation was maintained even after we controlled for depression, anxiety and PTSD [post-traumatic stress disorder],” Nadorff says. “So here are some of the biggest risk factors in the field people think of or assess for, but nightmares are adding something that the others are not capturing.”

Nadorff expanded on these findings in 2013 in a study published in Suicide and Life-Threatening Behavior, when he showed that the longer a person experiences nightmares (in months), the higher the suicide risk. In 2014, in a paper published in the Journal of Affective Disorders, Nadorff looked at how nightmares related to the number of suicide attempts and, specifically, what factors distinguish those who stop at one suicide attempt from those who will try again. “Depression doesn't, anxiety doesn't, all these common risk factors are not differentiating,” Nadorff remarks. Yet nightmares were linked to a fourfold increased risk of renewed attempts.

Other researchers have found similar results in other countries. The National FINRISK Study, a series of health surveys of the Finnish adult population, found that having frequent nightmares increased the risk for death by suicide more than twofold, according to data obtained by the Finland National Death Registry. A similarly large study from Sweden and a meta-analysis of 14 studies also showed that nightmares increase suicide risk.

In a 2014 study published in Sleep and conducted at the University of Pennsylvania, researchers found evidence that suicide is more likely to occur at night, especially between midnight and 6 A.M. And in a paper published in 2016 in Sleep Medicine Reviews, the same researchers proposed that just being awake at night increases the risk for suicide. Why? “One possibility is that being awake at night may be associated with increased utilization of alcohol and other substances, reduced social support, and easier access to weapons,” the authors suggested in the 2016 paper. “Another possibility is that insomnia and/or nightmares contribute to suicidal ideation and behavior by intensifying the individual's sense of hopelessness, isolation, and distress relative to the inability to sleep.” They concluded that targeted treatment for nightmares and insomnia should be incorporated into suicide prevention programs.

Most health care providers do not survey patients about nightmares, and most sufferers are unlikely to report them. Yet there are simple, fast and effective treatments, the most common being imagery rehearsal therapy (IRT), which focuses on modifying the nightmare through waking visualization. The first step is to imagine the nightmare and write it down before rewriting the story with a more desirable ending. This “happy” version of the nightmare is then visualized and rehearsed for 10 to 20 minutes during the day. The best part? This simple therapy can be effective at treating nightmares after only one to three sessions.

Still, suicide prevention remains a complex issue, and more work needs to be done to evaluate whether treating nightmares with IRT, in combination with existing interventions, can be effective, especially for those high-risk individuals who have already made one attempt.