Trauma-linked sleep problems affect nearly 7% of Icelandic women

Study: Trauma-associated sleep disturbances among women in a nationwide study. Image Credit: Frame Stock Footage / Shutterstock

In a recent study published in the journal Communications Medicine, researchers evaluated the prevalence of trauma-associated sleep disturbances (TASD) among Icelandic-speaking women aged 18-69 years in Iceland.

Trauma-associated sleep disorder (TSD) is a proposed non-diagnostic sleep phenotype that occurs after experiencing a traumatic event. It is characterized by hyperarousal during sleep, disruptive nocturnal behaviors (DNBs), and trauma-related nightmares (TRNs). One of the core symptoms of post-traumatic stress disorder (PTSD) is sleep disturbance, often lingering even after other symptoms subside.

TSD remains an investigational clinical phenotype that may co-occur with PTSD or persist independently. TSD research has primarily focused on male populations in high-stress occupations, including military service; as such, there is limited information about its prevalence in other populations, such as non-military and female populations.

About the study

In the present study, researchers investigated the prevalence of TASD and related factors among females in Iceland. They included Icelandic-speaking female residents aged 18-69 years who participated in the Stress and Gene Analysis cohort study. Individuals with cognitive brain diseases and those with missing data on TASD and life stressors were excluded. Participants completed online questionnaires about their health and trauma history.

Life stressor exposure was assessed using a modified Life Events Checklist for DSM-5 (LEC-5). Past-month TASD symptom criteria were evaluated using items from the PTSD Checklist for DSM-5 (PCL-5) and the Pittsburgh Sleep Quality Index (PSQI) Addendum for PTSD (PSQI-A). TASD was defined as the presence of TRNs and DNBs, exposure to a significant life stressor, and a PSQI-A score > 3. General sleep problems encountered within the past month were assessed using the PSQI.

Probable PTSD within the past month was assessed using the PCL-5. Anxiety and depressive symptoms were assessed using the General Anxiety Disorder (GAD-7) scale and the Patient Health Questionnaire (PHQ-9), respectively. Suicidal ideation, suicidal attempts, and self-harm in the past five years were assessed using the World Mental Health (WMH) Composite International Diagnostic Interview (CIDI). Sociodemographic data were also collected from participants.

TASD prevalence was estimated, and Poisson regression models calculated prevalence ratios for the association between TASD and psychiatric, sociodemographic, and trauma-related factors. Models were adjusted for education, age, employment status, personal income, relationship status, temporal proximity to the worst life stressor, and number of life stressors. Poisson Generalized Estimating Equations (GEE) models were used to assess age-related effect modification.

Findings

The study included 27,938 participants, with a mean age of 43.7 years. The prevalence of TASD was 6.9% in the sample. Most individuals were employed (81%) and were in a relationship or married (76%). About 39% of participants experienced two or three life stressors. Among PSQI-A symptoms, DNBs were the least frequent, while hot flashes and general nervousness were the most common. TASD prevalence was the highest in the 18-29 age group.

Having primary or secondary education, smoking, being unemployed, binge-drinking, or being single/widowed was associated with a higher TASD prevalence. Notably, TASD prevalence increased with the number of life stressors experienced. Repeated exposure to the worst life stressor was associated with a 48% increased TASD prevalence.

Participants with recent exposure to the worst life stressor (within the past year) had the highest TASD prevalence, while those with exposure more than two decades ago had the lowest. Some life stressors, such as physical and sexual violence, captivity, sudden violent death, sudden accidental death, life-threatening injury or illness, and stillbirth, were strongly associated with TASD. Combat/war-zone exposure also showed a strong association, although this estimate was based on a very small subgroup and should be interpreted cautiously.

The researchers also examined overlap with mental health symptoms. Furthermore, TASD was strongly associated with probable PTSD; 74% of participants who had TASD also showed probable PTSD. Participants with depressive symptoms, general sleep problems, or anxiety had an increased prevalence of TASD. Self-harm and suicidal ideation within the past five years were associated with TASD. A small subset of participants had TASD without probable PTSD or general sleep problems, supporting the possibility that trauma-related sleep disruption may occur outside broader PTSD symptomatology.

Conclusions

TASD prevalence was 6.9% among women aged 18-69 years in Iceland. Exposure to sexual and physical violence, stillbirth, and combat or war-zone exposure was associated with a substantially higher prevalence, although the combat-related estimate was imprecise. Temporal proximity and repeated exposure to the worst life stressor were associated with an elevated TASD prevalence.

Current age and recency of trauma appeared more relevant than age at first occurrence of the worst life stressor. TASD was strongly associated with PTSD, anxiety, and depressive symptoms. Because the study was cross-sectional and based on self-reported trauma and sleep symptoms, it cannot establish causality or confirm TSD using polysomnography.

Overall, the findings emphasize the potential value of early detection of TASD and targeted sleep-focused interventions.

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