A growing body of research indicates that sleep disturbances are associated with suicidal ideation and behaviors. This article (1) provides a critical review of the extant literature on sleep and suicidality and (2) addresses shared underlying neurobiological factors, biological and social zeitgebers, treatment implications, and future directions for research. Findings indicate that suicidal ideation and behaviors are closely associated with sleep complaints, and in some cases, this association exists above and beyond depression. Several cross-sectional investigations indicate a unique association between nightmares and suicidal ideation, whereas the relationship between insomnia and suicidality requires further study. Underlying neurobiological factors may, in part, account for the relationship between sleep and suicide. Serotonergic neurotransmission appears to play a critical role in both sleep and suicide. Finally, it remains unclear whether or not sleep-oriented interventions may reduce risk for suicidal behaviors. Unlike other suicide risk factors, sleep complaints may be particularly amenable to treatment. As a warning sign, disturbances in sleep may thus be especially useful to research and may serve as an important clinical target for future suicide intervention efforts.
Keywords: suicidality, sleep, nightmares, suicide risk factors
Suicide is a leading cause of death. Approximately 30,000 people die by suicide each year in the United States alone (Murphy 2000). Suicide kills more Americans annually than homicides, and although rates vary substantially by age, suicide ranks as the 11th most common cause of death. Attempted suicides are believed to far exceed this number. It is estimated that 10 to 25 nonlethal suicide attempts occur for every completed suicide (Maris 2002). Moreover, such attempts are responsible for more than 400,000 emergency room visits annually (Doshi et al 2005). Taken together, suicidal behaviors represent a complex, yet potentially preventable public health problem, with far-reaching personal and societal consequences. Improvements in the identification of risk factors for suicidal behaviors thus ultimately enhance our ability to intervene and prevent death by suicide.
Acute and chronic suicide risk is associated with social, psychological, and biological variables (Lewinsohn et al 1996; Mann et al 2001; Rowe et al 2006), and such factors are often further divided into precipitating and predisposing causes (Mann 2002). One growing area of research includes the study of sleep complaints and suicidality. Increasing evidence suggests that disturbances in sleep are associated with an elevated risk for suicidal behaviors. Both sleep disorders and general sleep complaints appear to be linked to greater levels of suicidal ideation and depression, as well as both attempted and completed suicide (Krakow et al 2000; Agargun et al 1997a; Fawcett et al 1990). In consideration of these findings, sleep problems and more specifically, significant changes in sleep, are now listed among the top 10 warning signs of suicide from the Substance Abuse and Mental Health Services Administration (SAMSHA) (National Mental Health Information Center 2005).
Clinical and epidemiological investigations of self-reported sleep disturbances and suicidal behaviors
Poor sleep quality, insomnia, and hypersomnia
Fawcett and colleagues conducted one of the first studies to prospectively examine sleep, depression, and suicide (Fawcett et al 1990). In a group of depressed patients, symptoms of global insomnia were more severe among those who completed suicide within a 13-month period. This finding suggested that insomnia may be considered a clinical indicator of acute suicidal risk, perhaps particularly when it appears in the midst of a depressive episode. Agargun et al (1997a) demonstrated a similar link between suicidality, depression, and sleep complaints. Depressed subjects suffering from either hypersomnia or insomnia showed significantly higher scores on measures of suicidality. In a separate study, these authors also examined self-reported sleep quality among depressed patients (Agargun et al 1997b). Subjective sleep quality was significantly more disturbed among suicidal versus nonsuicidal patients.
An association between poor sleep quality and completed suicide has been prospectively studied in several community samples of men and women. Among a large group of elderly participants, for example, poor self-reported sleep quality was linked to suicide within 10 years. Although depression showed the strongest link with suicide, poor sleep quality increased the risk for suicide by 34% (Turvey et al 2002). A recent investigation conducted in Japan demonstrated similar findings. Fujino et al (2005) showed that, among 13,259 middle-aged adults, only difficulty maintaining sleep at baseline, compared to other sleep disturbances (eg, difficulty initiating sleep, nonrestorative sleep), significantly predicted death by suicide 14 years later. In both of these studies, depression was not accounted for when examining the association between sleep and completed suicide. Such information would elucidate whether sleep disturbance stands alone as a risk factor for completed suicide or, conversely, whether such sleep complaints simply vary with increased depressive symptoms.
Similar to insomnia symptoms, nightmares are more common among suicidal versus nonsuicidal individuals with major depression. Research indicates that depressed patients with self-reported repetitive and frightening dreams are more likely to be classified as suicidal, compared to those without frequent nightmares (Agargun et al 1998). A similar relationship recently emerged in a prospective, population-based study conducted in Finland. Tanskanen et al revealed an association between nightmare frequency at baseline and completed suicides at follow-up 14 years later (Tanskanen et al 2001). Compared to subjects reporting no nightmares, those reporting occasional nightmares were 57% more likely to die by suicide. Among those with frequent nightmares, the risk for suicide increased dramatically; those endorsing frequent nightmares were 105% more likely to die by suicide compared to those reporting no frightening dreams.
Bernert and colleagues (2005) investigated the frequency and severity of nightmare symptoms, depression, and suicidality among 176 clinical outpatients using several validated symptom inventories. Results indicated that nightmares predicted elevated suicidal ideation, and this effect was independent of depression. Although this relationship emerged as a nonsignificant trend (p = 0.06), these findings suggest that nightmares may constitute a unique risk factor for elevated suicidality. More recently, Agargun and colleagues (2007) examined nightmare frequency, insomnia symptoms, and suicide attempt status among depressed patients with and without melancholic features. Depressed patients with melancholic features (N = 100) were compared to depressed patients without these features (N = 49). Participants were categorized further as having a history or no history of suicide attempts. Results revealed that melancholic patients with a history of suicide attempts showed higher rates of nightmares and insomnia symptoms compared to melancholic patients without a history of attempts. This study did not assess sleep variables using objective sleep tests; however, it is perhaps the first investigation to examine melancholic depression, suicidality, and sleep disturbances. The authors theorized that feeling worse in the morning as opposed to later in the day, a hallmark symptom of melancholic depression, may be associated with dream content, more negative affect, and in this way, greater risk for suicidality.
The entire paper can be read here:
The recent publication of Sleep Deprivation and Disease – Effects on the Body, Brain and Behavior is also an useful research manual:
As well, Combat Stress (FM 6-22.5) Sleep Deprivation, Suicide Prevention, a manual published by the U.S. Army, U.S. Military, Department of Defense, is also of interest in this subject. It is well known that Geronda Ephraim read WWII battle strategy books while he was on Mount Athos, “to help him understand the strategies of warfare.” If monks are soldiers in a heavenly army, and are in ceaseless battle until their last breath, perhaps manuals about suicide and sleep deprivation applied to physical and earthly warfare may also help: