Over 40,000 fatalities in the United States last year were due to suicide, a rate that has increased more than 20 percent in the last 10 years. And for every suicide, there are an additional 25 attempts. These statistics suggest one thing: that current interventions are not working and we need new methods for preventing people from taking their own lives. But where to start? Michael Nadorff, a psychologist at Mississippi State University, claims one treatable risk factor has been hiding in the dark: nightmares.

Over the past five years, Nadorff’s research has shown that nightmares are associated with a higher risk for suicide—and that among suicidal individuals, treating the former may be one innovative approach to preventing the latter.

In scientific terms, suicide risk is measured by three elements: thoughts of suicide, suicidal behaviors, and the likelihood with which a person believes they will die by suicide. In a 2011 study published in the journal Sleep, Nadorff and his colleagues evaluated suicide risk in 583 undergraduate students and then examined how symptoms such as anxiety, depression and nightmares were related to that risk. What he found was simple—the more severe the symptoms, the higher the suicide risk. However, when they looked more closely at the effect of nightmares, they found that having bad dreams predicted suicide risk above and beyond all the other factors.

“What amazed me at the time was that not only are nightmares associated with suicide, but the relationship 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 that 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 actual duration (in months or years) a person experiences nightmares matters. In other words, the longer you have the bad dreams, the higher the suicide risk. In 2014, in a paper published in the Journal of Affective Disorders, Nadorff went on to look at how nightmares related to the number of suicide attempts. Again, he wanted to see how all the different risk factors stacked up. If someone already has attempted suicide, which factors distinguish those who stop at one attempt from those who will try again? “Depression doesn’t, anxiety doesn’t, all these common risk factors are not differentiating,” Nadorff remarks. But nightmares increased the risk of reattempting suicide fourfold.

Other researchers have found similar results in other countries. The National FINRISK Study is a series of health surveys of the Finnish adult population that has been conducted every five years from 1972 to 2012, with a total of 76,071 respondents. Researchers at the University of Turku analyzed data from this large, population-based study and found that having frequent nightmares increased the risk for death by suicide more than twofold, according to information obtained by the Finland National Death Register. At the University of Gothenburg in Sweden, a longitudinal study published in Psychiatry Research found that, in a sample of individuals who had attempted suicide, those who suffered from nightmares were at greater risk of reattempting suicide over the next two years. Lastly, a 2012 meta-analysis of 14 studies published in The Journal of Clinical Psychiatry concluded that those who suffer from nightmares are 2.61 times more likely to exhibit suicidal behaviors than individuals who do not have nightmares.

Why? What is it about having nightmares that might provoke suicidal behavior?

The first thing to note is the situational context of having a nightmare. Awakening from a bad dream is a severely distressing and overwhelming experience. You are jarred from sleep by disturbing imagery, lying alone in the dark with a racing heart. Maybe you dreamed of a cheating ex-wife, the recent death of a loved one, or losing your job. Now you are trapped in this anxious state and unable to fall back asleep, ruminating on emotional problems you probably would prefer to avoid.

“You don’t have the same support you have during the day, so you have fewer barriers” to acting on suicidal thoughts, explains Nadorff. In this light, a nightmare can tip those on the brink of suicide over the edge.

In fact, 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. For the study, they obtained estimated times of more than 35,000 suicides from the National Violent Death Reporting System. When accounting for the proportion of the population awake at each hour, the suicide rate per hour peaked at 16 percent between 2 and 3 A.M., and then dropped to 2 percent across the day between 6 A.M. and midnight. In a paper published in Sleep Medicine Reviews in 2016, the same researchers propose that just being awake at night increases risk for suicide, and conclude that targeted treatment for nightmares and insomnia should be incorporated into suicide prevention programs.

Unfortunately, most healthcare providers do not survey patients about nightmares and most sufferers are unlikely to report them. In fact, in a recent paper published in Journal of Clinical Sleep Medicine in 2015, Nadorff and colleagues examined this problem. “I ask suicide clinicians all the time, when you do a risk assessment, do you ever ask about nightmares? And no one ever does. No one ever does.”

Luckily, there are simple, fast, and effective treatments for nightmares, 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 ending” version of the nightmare is then visualized and rehearsed for 10 to 20 minutes during the day. IRT is well tolerated by patients, and significantly reduces nightmare frequency and severity over the long term, research suggests.

One advantage of nightmare therapy is that it may be easier for patients to talk about bad dreams rather than always focusing on depression or suicidal thoughts. “People seem to enjoy it,” Nadorff says, adding, “it’s one of my favorite treatments to do.” IRT also benefits the waking symptoms associated with suicidality. “You treat the nightmares, and the depression gets better, the anxiety gets better, so all these things we need to worry about are getting better anyway.”

The best part? This simple therapy can be effective at treating nightmares after only one to three sessions. While more longitudinal work needs to be done to evaluate this approach, treating nightmares with IRT may be an ideal additional treatment for suicidality, especially in those who have already made one attempt.