We are always seeking to improve our understanding of the risk factors for suicide

Article in review: Hedstrom, A., Bellocco, R., Hossjer O., Ye, W., Lagerros Y. & Akerstedt, T. (2021). The relationship between nightmares, depression, and suicide. Sleep Medicine, https://doi.org/10.1016/j.sleep.2020.11.018

Summary: Suicide prevention seeks to minimise the factors that increase suicide risk while increasing the factors that protect people from suicide. There are some independent characteristics and things we can do in communities that may help protect people from suicidal thoughts and behaviour. There are limited studies about protective factors as there are about risk factors, but recognising and understanding them is very important.

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If a patient, client, employee, or colleague mentions they have been having nightmares, could this be an indicator of an increased risk of suicide? A recent study has sought to determine if there is a link between nightmares, depression, and suicide.

What exactly are nightmares and who has them?

Nightmares are terrifying or disturbing dreams that usually involve threats to a person’s survival, safety, or physical health. They may occur as the result of a post-traumatic stress reaction, be idiopathic or occur as the result of drug use. Frequent nightmares have been related to general psychopathology and psychiatric disorders, including post-traumatic stress disorder, major depressive disordered, schizophrenia, and bordering personality disorder. Some people experience nightmares over a long period of time. There is also a substantial genetic effect on the disposition to have nightmares.

Landmark Swedish study

A landmark longitudinal and very large study was commenced in Sweden in 1997. The Swedish Cancer Society organised a four-day nationwide fund-raising event. Participants at the event were invited to fill out a 36-page questionnaire regarding demographics, lifestyle, and medical information. Participants were asked to include their individual Swedish registration number so that follow-up data could be obtained and assessed where relevant.

Study cohort

A whopping number of people participated in the study by completing a detailed questionnaire- 43,863 people from 3600 Swedish cities. Following exclusions related to responses and eligibility, a final sample of 40,902 was assessed. 64% were women and 34% men. The inclusion of the identifier number meant that the population could be tracked and the incidences of suicide occurring until 2018 could be considered. Mortality data were obtained by linkage with the cause of death register, and follow-up ended at the time of death, emigration, or on 30 April 2018. During this time, 8640 deaths occurred of which 69 were suicides.

Findings

Overall, this study found no evidence suggesting that night marked influence the risk of suicide. However, nightmare frequency correlated with self-reported depressive and anxiety symptoms, sleep during, and insomnia. Among people who indicated they experienced nightmares, there was a higher rate of diagnosis of depression during the study period. Results were in alignment with previous research that suggested an association between nightmare frequency and the general level of psychopathology, mood, and anxiety disorders, and other sleep disorders.

Nightmares were not associated with an increased incidence of suicide amongst non-depressed patients and did not further increase the incidence of suicide associated with depression. This suggests that nightmares may reflect pre-existing depression. Given that genetics are contributors to both depression and nightmares, this may contribute to comorbidity in these conditions.

Psychiatric traits are predictors for nightmares, however, there is no evidence to suggest that the occurrence of nightmares can be seen as a predisposition to psychiatric illness or psychological problems.

Takeaway

People experiencing both depression and nightmares may be at an increased risk for death by suicide. When supporting a person who is both depressed and experiencing nightmares, it is worthwhile to consider interventions that target and address both of these conditions, to provide more comprehensive care with additional therapeutic benefit.