'When Reason Sleeps': Suicide Risk Peaks at Night

Batya Swift Yasgur, MA, LSW

April 23, 2020

The risk for suicide is higher at night than at any other time of day, new research shows.

In findings that may offer an opportunity for suicide prevention, investigators found that the risk of dying by suicide between midnight and 6:00 AM was roughly three times higher than at other times of day regardless of month, method of suicide, or a wide range of other factors.

"The take-home message is that helping at-risk patients sleep through the night may be an excellent way to reduce suicide risk," lead author Andrew Tubbs, an MD/PhD candidate at the Sleep and Health Research Program, Department of Psychiatry, University of Arizona, Tucson, told Medscape Medical News.

The study was published in the March/April issue of the Journal of Clinical Psychiatry.

Time, Method of Suicide

Previous research suggests that waking at night is linked to a heightened risk for suicidal thoughts and behaviors, the investigators note.

"The motivation for this study was to expand our understanding of factors that increase suicide risk at night. Since night length changes across seasons, we wondered if suicide risk at night would be lower during summer months and higher during winter months," he said.

"Similarly, we thought the availability of some suicide methods may vary by time of day — for example, perhaps nighttime would involve more 'silent' methods, such as poisoning or asphyxiation, over 'louder methods,' such as firearms or vehicle suicides," Tubbs added.

The investigators also examined whether the risk for nocturnal suicide was influenced by demographic or geographic factors.

They analyzed data on 35,338 suicides from the US National Violent Death Reporting System for the years 2003–2010.

Time of suicide was divided into four categories ― night (midnight to 5:59 AM), morning (6:00 AM to 11:59 AM), afternoon (noon to 5:59 PM), and evening (6:00 PM to 11:59 PM).

Suicide methods included guns, asphyxiation, poisons, falls, vehicles, sharp weapons, drowning, and fire. Demographics included sex, age, race, and ethnicity. Geographic analyses were based on latitude (at or above 40° N or below 35° N) and region (West, Midwest, South, and Northeast).

Raw data revealed that more males than females died by suicide (n = 28,700 vs 6636), that most suicides occurred in May (n = 3196), and that the most common method of suicide was by firearms (n = 21,937). Most suicides occurred in those aged 45 to 54 years (n = 7252) and in whites (n = 31,239) and non-Hispanics (33,384).

Interestingly, most suicides occurred during the afternoon (n = 11,381). Tubbs explained that suicides are more common during the day, typically around midday, when most people are awake, "so the 'eligible' population for suicide is highest at noon," he said. However, this does not translate into level of risk, so the researchers accounted for nocturnal wakefulness in the analyses.

"When Reason Sleeps"

The incidence rate ratio (IRR) at night was 3.18, significantly higher than at any other time of day across all months. The highest IRR was in May (3.90), and the lowest was in November (2.74).

An analysis of variance (ANOVA) for month and time of day indicated that the IRR varied significantly only by time of day (P < .001), not across months (P = .33) or by interaction (P = 1.00).

Initially, a 2-way ANOVA showed that the risk for suicide varied both by time of day and by suicide method (both Ps < .001), but the interaction between them was not significant (P = .3026). The mean (SD) nocturnal IRR was 3.09 (.472) across all methods.

Although more than half of suicides involved firearms, "no method had a significantly higher risk at a specific time than any other method at that same time," the authors note. In addition, an analysis of nocturnal risk by method showed no differences on the basis of sex, age, ethnicity, latitude, and region.

"There are probably many overlapping reasons why the risk of suicide is highest at night. Certainly, social and family supports are minimized if you are awake and everyone you know and love is asleep — you're isolated, no one's reaching out to you, and there's no one there to stop you," said Tubbs.

On the other hand, "recent evidence indicates nighttime changes in brain function can impair impulse control, decision making, and long-term planning, which can definitely increase suicidal behaviors.

"Whether these changes are due to sleep deprivation or circadian rhythms is unknown, but it is clearly dangerous to be awake when reason sleeps," he said.

Clinicians who treat suicidal patients, said Tubbs, should ask about sleep. If a patient has a problem with sleep, cognitive-behavioral therapy for insomnia should be initiated. This first-line treatment, he said, is more effective and much safer than prescribing a hypnotic.

Difficult Hours

Commenting on the study for Medscape Medical News, Christopher W. Drapeau, PhD, assistant professor, Department of Education, Valparaiso University, Indiana, said that sleep disturbances "may be a modifiable risk factor for suicide, especially when sleep disturbances are cited by patients as a primary reason for wanting to attempt suicide."

Drapeau, who was not involved in the study, said that this "presents an area for health professionals to focus on when developing treatment approaches based on patient information collected during suicide risk screenings and comprehensive risk assessments."

Also commenting on the study for Medscape Medical News, Michael Nadorff, PhD, associate professor of psychology, Mississippi State University, Starkville, who was not involved with the study, said the study findings are clinically relevant.

These data, he said, inform clinicians about when patients are most likely to be struggling with suicide intent and offer an opportunity to develop safety plans to mitigate suicide risk during these "difficult hours" when coping mechanisms are at a low ebb and sources of support are unavailable.

Support for the study was provided by grants from the National Institutes of Health and the Veterans Administration. Tubbs and coauthors, Drapeau, and Nadorff report no relevant financial relationships.

J Clin Psychiatry. 2020;81:19m12964. Abstract

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