Recent reports support the theory that insomnia often is associated with a hyperarousal state marked by increased activation of the hypothalamic-pituitary-adrenal (HPA) axis. In a study presented at the Associated Professional Sleep Societies 19th Annual Meeting (June 2005), patients with insomnia demonstrated a 71% greater adrenocorticotropic hormone response, which results in higher levels of secreted cortisol, compared with the patients in the control group. The investigators concluded that the data reflected the HPA dysregulation or hyperarousal state seen in primary insomnia.
Cortisol increases when individuals have physical or psychological stress, which tends to drive sleeplessness. Cortisol raises blood sugar and ensures that enough energy is produced to deal with stress factors. Treatments that address the hyperarousal state of insomnia may not only improve the quality or quantity of sleep but also reduce the risk of developing psychiatric or medical illnesses associated with hyperarousal.