Latest article: Breaking the hyperarousal cycle: How to support sleep, stress regulation and daytime calm

WHAT IS HYPERAROUSAL?

Hyperarousal can be conceptualised in many ways, though it typically comprises a combination of physiological indicators, emotional states, cognitive symptoms, and behavioural disturbances.

Hyperarousal is believed to be an important factor contributing to the aetiology and maintenance of a range of disorders, including insomnia, anxiety and stress-related disorders such as post-traumatic stress disorder (PTSD).¹⁻³ Research also suggests it plays an important role in depression, autism, and even in people experiencing tinnitus.⁴⁻⁶ Greater hyperarousal symptoms are also associated with an increased risk of all-cause mortality or major adverse cardiovascular events in survivors of cardiac arrest.⁷

There are several biological mechanisms that contribute to a hyperaroused state. The sympathetic nervous system (SNS) is a branch of the autonomic nervous system that plays a crucial role in our ‘fight or flight’ response. In response to a stressor, fibres from the SNS innervate peripheral organs and tissues throughout the body to control diverse physiological processes, including cardiac output, body temperature, blood glucose levels and immune function.⁸ The neurotransmitters adrenaline and noradrenaline play an important role in SNS activity.

The hypothalamic-pituitary-adrenal (HPA) axis also plays an important role in our stress response, releasing and regulating hormones such as cortisol to help the body respond to a stressor. Cortisol mobilises energy stores, increasing blood glucose levels to provide the body with a readily available energy source, enhances cardiovascular function to prepare the body for a fight-or-flight response, and dampens the immune response to conserve energy for immediate survival needs.⁹

Neurological activity in brain regions such as the brainstem, hypothalamus, basal forebrain, and thalamus is influenced by the SNS and the HPA axis, but in turn also plays important independent roles in physiological arousal.¹⁰ Overactivation of the SNS, the HPA axis, and the previously mentioned brain regions are important processes involved in hyperarousal.