January 20, 2021

More on Sleep Disturbance and Suicide

As we have previously presented, sleep disturbance is correlated with suicidal behaviors and risk factors. Important work on understanding these connections is coming out of Dr. Grandner’s lab, including wakefulness at night as a specific concern out lined in this From the Scientist summary of a recent paper. Evidence is building that increased awareness and treatment of sleep disturbances across a variety of health and life conditions may prevent suffering and loss.

 

From the Scientist:

Summary of “Relationship of Nocturnal Wakefulness to Suicide Risk Across Months and Methods of Suicide”

By Andrew S. Tubbs, BSc; Fabian-Xosé Fernandez, PhD; and Michael A. Grandner, PhD, MTR

The motivation for our research outlined in this paper comes from statistics showing that the U.S. suicide rate has risen 33% since 1999. Suicide has emerged as a national public health crisis, but the epidemic has hit teenagers and young adults really hard; in these groups, reported suicides are at their highest levels since the government began collecting statistics in 1960. The data are sobering, and the fact that these numbers only continue to increase has compelled us to examine some of the reasons for why younger individuals might commit suicide. When approaching this topic, it’s important to note that assumptions about depression and mental illness no longer explain the majority of cases: Most people who commit suicide don’t have a diagnosed mental health condition at time of death.

For decades, sleep disturbance has been suggested as a possible risk factor for suicide. However, a starburst of recent investigation by us and others across the globe has brought this association into powerful focus: over 100 studies now document a prospective directional relationship between baseline sleep problems and later suicidal thinking, attempts at self-harm, and deaths. This connection is observed even when depression is factored out as an issue. At this juncture, the critical questions for us are: What aspects of “sleep disturbance” promote increased suicide risk and why?

To answer these questions, we first wondered whether one specific kind of sleep problem increased risk preferentially over another. Our analyses suggested that this kind of granularity didn’t matter: someone with inadequate sleep experiences the same increased risk of suicidal thinking and behavior irrespective of whether their sleep problems are traced back to insomnia or having repeated nightmares, or just generally bad sleep. This presented the possibility that simply being awake during the middle of the night might be a common element that ties the association together.

To investigate whether nighttime wakefulness might be an issue, we analyzed data from the CDC’s National Violent Death Reporting System, which had collected information from over 35,000 individual suicides committed between 2003-2010. These reports provided an estimated time of fatal injury connected to the suicide and other information related to the person’s age, gender, and race/ethnicity. We compared these data with population-level wakefulness data that were collected through the American Time Use Survey, a survey done by telephone each year from people aged 15 years and older across the United States. The Time Use Survey estimates the percentage of the population awake at each hour of the 24-hour day.

Cross-checking these two datasets, we determined that the number of suicides at night vastly exceeded the number of suicides expected given the proportion of the population awake at that time. This equated to a 3.6-fold increased risk of suicide at night (between midnight and 6:00am) that was seen equally across younger and older individuals, men and women, and across the seasons. From this analysis, we concluded that the highest normalized incidence of suicide was around 3:00am.  

At present, we are trying to organize laboratory studies that will help us answer the question of why nighttime wakefulness increases someone’s vulnerability to suicidal thinking and behavior. Two interconnected possibilities stand out to us. The first has to do with the timing of highest normalized suicide incidence with respect to a person’s natural circadian variations of cognition and emotion: The highest incidence coincides with when there is a natural bottoming of our cognitive ability and our ability to regulate negative emotions (all coalesce at 3:00am). This raises the question of whether poor brain function in the middle of the night might abet suicidal thinking, as described in this recent Case Report.

The second possibility, pursuant to the first, is that the overnight vulnerability period we’ve suggested only becomes an issue if someone has already experienced chronic sleep loss. While temporal patterns for fatal suicidal injury have been established, we don’t know anything about the sleep history of the individuals affected by suicide. It could be that chronic sleep deprivation is an essential trigger. To that end, we are organizing experiments that will tell us whether a complete lack of sleep for 2-3 days induces a special kind of anxiety syndrome. We speculate that the symptoms of this anxiety syndrome would be present throughout the day, but would lead to a precipitous loss of cognitive and emotional control in the middle of the night thus driving suicidal thinking and significantly impairing a person’s impulse control between midnight and 6:00am.

If these hypotheses are supported by laboratory data, they could pave the way towards developing, institutionalizing, and prioritizing the provision of suicide-prevention services at night.