Sleep under stress: the complex web of fear, hypervigilance and mental health in a low socioeconomic status community in South Africa

Correia, Arron Taylor Lund

Sleep under stress: the complex web of fear, hypervigilance and mental health in a low socioeconomic status community in South Africa

Thesis / Dissertation

2025

Abstract

Introduction: There is a well-established bidirectional relationship between sleep and mental health. Furthermore, low socioeconomic status (SES) environments have been linked to both poorer sleep and mental health, at leastin part due to a lack of perceived safety. Specifically, individuals who feel unsafe or vulnerable in their neighbourhoods may either delay sleep in favour of remaining alert to potential threats or experience hypervigilance throughout the night. This state of hypervigilance is typically characterized by heightened sympathetic nervous system activity and reduced parasympathetic tone, which can be quantified through measures of autonomic nervous system function, such as heart rate variability. Heart rate variability (HRV) is a non-invasive measure of autonomic regulation of the heart which can be divided into time and frequency domain variables. Frequency domain variables are derived from the spectral power of the electrocardiography signal and include very low, low and high frequency power measures (VLF, LF and HF power, respectively). VLF and HF power reflect sympathetic withdrawal and parasympathetic input, respectively while LF is understood to reflect a combination of sympathetic and parasympathetic input. Lower HRV has previously been linked to various mental disorders, including depression and anxiety, and has been included as a contributing factor in the hyperarousal model of insomnia.

Keywords

Mental Health

Reference:

Collections

PhD / Doctoral

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