Presenters from SLEEP 2022 contextualized some of the recent research showing the impact of sleep disorders on aspects of mental health, including depressive symptoms and suicide.
During a presentation entitled “Sleep and Mental Health,” researchers gathered to contextualize some of the recent research showing the impact of sleep disorders on aspects of mental health, including depressive symptoms and suicide.
Insomnia and Depression Prediction
Past longitudinal studies have shown a link between insomnia and depression, but the underlying mechanisms of this relationship have not been fully realized. The researchers proposed that emotion regulation could be a potential mediating mechanism; however, empirical tests of the effect have been limited.
The researchers decided to conduct a study that would examine the individual relationship between insomnia and depressive symptoms over a 14-day period to assess whether insomnia symptoms on a given night would positively predict depressive symptoms the following day via emotion regulation.
In total, 60 adults between 18 and 65 years old with elevated insomnia symptoms, demonstrated by having an Insomnia Severity Index score of 10 or above, were enrolled in the analysis. The participants were tasked with filling out diary entries in the mornings and evenings and were given an actigraph to wear for 14 days.
The morning diary entries were to measure emotional reactivity using the International Positive and Negative Affect Schedule, emotional regulation strategy use through the Emotion Regulation Questionnaire and Cognitive Emotion Regulation Questionnaire, and depression, as determined by the Center for Epidemiologic Studies Depression Scale. The researchers utilized multilevel modeling to assess the within-individual associations and controlled for age and gender.
The results showed that shorter total sleep time in a single night predicted greater depressive symptoms the following day (P = .028). Additionally, sleep quality was found to have a negative association with next-day depression at the between-individual level (P = .003). Negative reactivity was observed to partially mediate the relationship between the quality of the participants’ sleep and depressive symptoms (P = .008), total sleep time and depression (P = .11), and sleep efficiency and depression (P = .002) at the between-individual level.1
The researchers said that in addition to finding an association between daily sleep time and depression, their findings suggested, “that one of the facets of emotion regulations, namely negative reactivity, plays a mediating role in the insomnia-depression relationship.” However, emotional reactivity and emotion regulation strategy use may not vary substantially across days.
Nocturnal Suicide and Possible Risk Factors
Suicide risk is greater at night after adjusting for population wakefulness, which researchers have hypothesized may be due to sleep- and circadian-dependent changes in neurophysiology to promote sleep. However, the characteristics of people who die by nocturnal suicide may differ from those who die by suicide during the day.
Researchers conducted an archival analysis of the National Violent Death Reporting System from 2003 to 2017 and identified 77,784 suicide deaths with the time of fatal injury. Cases that occurred between 5 a.m. and 10:59 p.m. were considered daytime suicides and cases that occurred between 11: p.m. to 4:59 a.m. were considered nocturnal suicides. All cases were categorized by age, sex, race, ethnicity, marital status, military service, education, history of suicidal thoughts, and prior diagnosis of anxiety, bipolar disorder, depression, post-traumatic stress disorder (PTSD), and schizophrenia. The presence of an opiate or cannabis and blood alcohol level (BAL) on autopsy were also considered.2
Every sociodemographic aspect included in the analysis was observed differently between nocturnal and daytime suicides. Nocturnal suicides were more common among those who were diagnosed with bipolar disorder or PTSD, had an elevated BAL, or had tested positive for cannabis.
Additionally, nocturnal suicide among people with a high BAL was more common in younger adults between the ages of 35 and 64 years. Notably, the risk of nocturnal suicide was 17% greater among those with a prior history of suicidal ideation and 13% lower among those diagnosed with depression.
“Further research is needed to target suicide prevention efforts at appropriately times for those with mood, substance, and alcohol use disorders,” the researchers wrote.