The Correlation Between Sleep Disturbance and Suicide

The battle against suicide took a step backward between 2011 and 2012. According to the CDC, while 8 of the 10 most common causes of death in the US showed statistically significant reductions in the death rate over the span of merely 1 year, one cause of death among the top 10 showed a significant increase-suicide.¹ More than 40,000 Americans will complete suicide this year. Clearly more needs to be understood and done to reverse these trends.

All psychiatrists know the risk factors for suicide. Some are unmodifiable, such as advancing age, male sex, and being white. Others are potentially modifiable, such as depression, drug abuse, hopelessness, and social isolation. Among the newest modifiable risk factors to join the list are insomnia and nightmares.

[[{"type":"media","view_mode":"media_crop","fid":"41415","attributes":{"alt":"© sam100/shutterstock.com","class":"media-image media-image-right","id":"media_crop_1692724372772","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4368","media_crop_rotate":"0","media_crop_scale_h":"155","media_crop_scale_w":"180","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right;","title":"© sam100/shutterstock.com","typeof":"foaf:Image"}}]]The first reports of an association between insomnia and suicide death appeared about 25 years ago.² The passage of time has produced a voluminous literature of more than 60 original research reports that show a statistical association between sleep disturbance and suicidal thinking, suicidal behavior, and suicide death. These reports come from North America, Europe, and Asia, and encompass children and adolescents, young adults, and the elderly.

The clever skeptic would guess that the association between sleep disturbance and suicide is spurious and is better explained by the well-known association of sleeping problems with depression; therefore, it must actually be the depression that is driving the association with suicide. And yet, when the presence and intensity of depression are controlled for within the statistical analysis, the relationship between sleep problems and suicide still stands. The odds ratio between insomnia and suicidal ideation is approximately 2.0. Moreover, the intensity of suicidal ideation co-varies with the intensity of insomnia during the course of clinical treatment for depression.³

While much of the relevant literature has been about insomnia and suicide, there are reports that more specifically link nightmares with suicide. The association between nightmares and suicide (as judged by the size of the odds ratio) may be greater than the association between insomnia and suicide, per se. The odds ratio for insomnia and suicidal behavior has been reported as 7.0, while the odds ratio for nightmares and subsequent suicidal behavior is as high as 8.2.⁴ In addition, hypersomnia may also be linked to suicide.⁵

Risk factors

What explains these associations, especially when 2 seemingly opposite phenomena such as insomnia and hypersomnia are linked to suicide? One explanation is the simple concept of “burden of illness.” It is well known that a chronic medical illness is a risk factor for suicide, so perhaps the burden of living with insomnia or hypersomnia becomes the “straw that breaks the camel’s back.”

The strength of the association between sleep disturbance and suicide would suggest that many suicide deaths happen at night, yet the opposite seems to be the case. Very few suicide deaths occur during the nighttime hours, followed by a sharp rise in suicide death rates through the morning hours and a decline again toward evening.6 Therefore, if sleep disturbance is related to suicide, it may be through the effects of sleep disturbance on daytime psychological or physiological function.

Both insomnia and hypersomnia are associated with impairments in cognitive functioning.⁷ Patients with insomnia have trouble in problem solving, and deficits in problem solving have been described in persons who have survived suicide attempts.⁸ In this scenario, the person who is dealt a major setback, such as a broken relationship or job loss, is unable to produce a solution to the problem if he or she has insomnia; this leads to the worst possible solution. Hypersomnia, like insomnia, is also associated with deficits in cognition.

A different possibility is that living with insomnia compounds any tendency toward hopelessness. Hopelessness is one of the most consistently replicated psychological findings in suicidal persons. In the field of sleep medicine, it is well know that persons living with chronic insomnia develop cognitive distortions about their sleep, in much the same way that suicidal persons might develop cognitive distortions regarding their future. Insomniacs can fall prey to the belief that they can do nothing to help themselves, that insomnia will ruin their life, and that whether they will sleep well or poorly on a given night is a total crapshoot.

Suicidal ideation

The Dysfunctional Beliefs and Attitudes about Sleep (DBAS) scale has been used to catalogue distorted views about sleep. Although the word “hopeless” never appears in the DBAS scale, many of the items in the scale imply a certain degree of hopelessness or futility regarding the sleep of the person with insomnia. It had initially occurred to me that the DBAS scale was merely a reframing of the concept of hopelessness that was so well described in suicidology.

Our research team began to evaluate some of these ideas by examining the intensity of suicidal ideation (as measured by the Scale for Suicide Ideation [SSI]) in a sample of well-characterized depressed outpatients.⁹ We found that the intensity of suicidal ideation closely tracked the intensity of insomnia over the course of treatment for depression.

This relationship was then examined in stable outpatients as well as in suicidal patients in the emergency department. We were surprised to find that the traditional notion of hopelessness as measured by the Beck Hopelessness Scale did not track along with the DBAS scale (Pearson’s r = 0.2; NS). It seems that regular hopelessness and sleep hopelessness are 2 different things! This finding must be viewed as preliminary and bears replication.

We also found that after taking into account the effects seen on the DBAS and the effects of nightmares, insomnia no longer made a contribution to the intensity of suicidal ideation, thus verifying the importance of understanding the role of nightmares in suicide risk. Preliminary data from a different sample of patients with depression, insomnia, and suicidal ideation suggest that both insomnia and hypersomnia independently contribute to the intensity of suicidal ideation. Thus, we are finding that a wide array of sleep-related concepts may contribute to suicidal ideation, including insomnia, hypersomnia, dysfunctional beliefs about sleep, and nightmares.

Biological considerations

Apart from psychologically based hypotheses to explain the relationship between insomnia and suicide, there are also biological considerations. Abnormally low serotonin function in the brain is among the best-replicated findings in human suicide, and animal data suggest that sleep loss desensitizes brain serotonin receptors.¹⁰ The psychobiology of insomnia strongly suggests that insomnia is a disorder of hyperarousal. That is, the sleeplessness of insomnia is better understood as an alerting system in overdrive, rather than a sleeping system that is broken.¹¹ This conceptualization is supported by brain PET imaging, EEG data both awake and asleep, and metabolic studies of whole-body oxygen consumption.

Understanding insomnia as a state of hyperarousal is consistent with the clinical view that there is a greater risk of suicide in patients who are agitated or becoming more active. This concept is also consistent with activation syndrome, which has been applied to the feelings of psychomotor restlessness that some patients feel with the initiation of treatment with an SSRI; this may be a period of acute risk for suicide.

Hypervigilence (and perhaps hyperarousal) is also a key feature in patients with PTSD. It has been hypothesized that excessive CNS adrenergic tone explains some of the symptoms of PTSD.¹² So hypervigilence and hyperarousal are common features of insomnia and PTSD-related nightmares, and both insomnia and nightmares are, in turn, related to suicide. The psychological aspects of nightmares may also contribute to suicide because the patient cannot find relief either during the day or during the night.

Current and future interventions

The rapid growth of observational studies on the topic of sleep disturbance and suicide has not been translated into an intervention. There are, in fact, very few randomized controlled trials (RCTs) of any intervention in patients with active suicidal ideation. There are some studies on the risk for suicide on the basis of prior suicide attempts or behavior, and these have found support for clozapine and lithium because of their specific antisuicidal effect.^13,14 In addition, open-label studies of electroconvulsive therapy (ECT) have suggested that suicidal ideation recedes rapidly with ECT.¹⁵ But there are few RCTs that specifically recruit an enriched sample of patients with active suicidal ideation.

Indeed, active suicidal ideation is a routine exclusion criterion in most psychiatric RCTs that are supported by pharmaceutical companies, because companies try to avoid the occurrence of serious adverse events. For that matter, university institutional review boards may be reluctant to approve RCTs that specifically recruit suicidal patients for fear that a series of serious adverse events could reflect badly on the university. As a result, there is scant information regarding the efficacy of most pharmaceuticals to treat active suicidal ideation. This recruitment discrimination is not much different from the practice 40 years ago of primarily recruiting white men for cardiovascular RCTs, resulting in a disenfranchisement of women and minorities from the generalizability of the RCT results.

Our research team is moving forward with an RCT for adults with MDD, with the requirement that they simultaneously have insomnia and active suicidal ideation. The study, Reducing Suicidal Ideation Through Treatment of Insomnia (REST-IT), is supported by the NIMH. The design includes the provision of open-label fluoxetine for 8 weeks, coupled with blinded randomization to zolpidem controlled-release or placebo at bedtime. While the study is still in progress and results are not yet available, early efforts have emphasized processes to enhance safety.¹⁶ Other investigators are looking at the utility of psychotherapeutic techniques to treat sleep problems, such as cognitive-behavioral therapy for insomnia or imagery rehearsal therapy for nightmares, as a means to reduce suicidal ideation.

Conclusions

Regardless of the results of the REST-IT study, there is sufficient evidence to recommend that the emergence or worsening of insomnia or nightmares be viewed as a sign of suicide risk, at least in patients with depression. Both new patients and established patients who complain of a new or escalating problem with insomnia or nightmares should be queried regarding the presence of suicidal ideation.

The vast majority of the research on the link between sleep disturbance and suicide has been derived from population studies or samples of depressed patients. There is a small but growing body of work showing that sleep disturbance is also linked to suicidal ideation in persons experiencing alcohol use disorders. Less is known about the relationship between sleep problems and suicide in persons with schizophrenia. Extension of the finding of a link between sleep and suicide to persons with schizophrenia would pose the possibility that the association between sleep and suicide is a universal feature of psychiatric illness.

Disclosures:

Dr McCall is Case Distinguished Chair in the department of psychiatry and health behavior at the Medical College of Georgia, Georgia Regents University in Augusta. He reports that he has received research support from the NIMH and the American Foundation for Suicide Prevention; he is Scientific Advisor for Merck and Luitpold; he has received CME honoraria from Global Medical Inc; and he receives royalties from Wolters Kluwer Publishing.

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