Sleep and arousal in adult survivors of chronic childhood trauma

Abstract

Exposure to traumatic stress during the developmental period has a profound impact on physical and psychological well-being. While survivors of childhood trauma often report sleep disturbance, the nature and characteristics of sleep disturbance and the underlying mechanism are largely unknown. Existing studies on clinical samples suggested that hyperarousal might interfere with sleep onset and maintenance, and dissociation might be associated with attenuated arousal. To investigate the complex relationships among sleep, arousal, and dissociation in childhood trauma survivors, three studies were conducted using samples of community-dwelling adults in Hong Kong.

Study 1 examined the differences in subjective sleep quality and sleep-related experiences among individuals exposed to short-term, chronic, and no childhood trauma, and evaluated if the chronicity of trauma altered the relationship between childhood trauma and sleep. Nine-hundred-and-fourteen adults completed an online survey on sleep, trauma-related symptoms, and psychological distress. Study 2 extracted the data from Study 1 and examined the factor structure and psychometric properties of the Chinese version of the Dissociative Experiences Measure, Oxford (HKC-DEMO). Study 3 examined the mediating role of arousal and the moderating role of dissociation in the relationship between childhood trauma and sleep. Fifty survivors of chronic childhood trauma and their age-and-gender-matched controls who reported no history of childhood trauma completed a week of sleep diary and an overnight portable polysomnography assessment. High-frequency heart rate variability (HF-HRV) and skin conductance level (SCL) were also assessed at baseline and under distress to evaluate autonomic arousal.

Results from the three studies showed that compromised sleep was found in survivors of chronic childhood trauma, but not in survivors of short-term childhood trauma, after controlling for demographic factors and current psychological distress. Specifically, chronic childhood trauma survivors had poorer sleep quality, longer sleep onset latency, and more wake time after sleep onset. However, such impairment in sleep was only found in subjective reports, but not in objective polysomnography assessments. Besides, hyperarousal, as indicated by heightened subjective pre-sleep arousal and decreased HF-HRV, was found in chronic childhood trauma survivors. Only subjective pre-sleep arousal mediated the association between childhood trauma and sleep. Furthermore, HKC-DEMO showed a five-factor structure and was reliable and valid for the assessment of dissociation in Chinese adults. Dissociation might moderate the association between childhood trauma and sleep such that the relationship between PTSD symptoms and compromised sleep appeared weaker in individuals with higher levels of dissociation.

Overall, exposure to chronic childhood trauma was associated with compromised sleep health and hyperarousal might be the underlying mechanism. Individual differences in dissociation might moderate the strength of the trauma-sleep association. While sleep and arousal regulation might mediate the impact of childhood trauma on physical and mental health in adulthood, improving sleep health and autonomic functioning should be regarded as the targets for prevention, assessments, and interventions for survivors of childhood trauma.