Challenging the Inflammatory Response System in Insomnia Disorder

Sleep is critical for the regulation and maintenance of biological systems, and sleep deficiency, such as insomnia, has been shown to be associated with elevated risks for cardiovascular, metabolic, and mood disorders.

Despite the high prevalence of insomnia in the population, the investigators understanding of the biological consequences of the disorder with respect to inflammatory, autonomic, and stress system markers is limited, and often not consistent.

In addition, insomnia may not only alter the basal activity of these systems, but may change their reactivity to other stressors and challenges. In support of this assumption are findings showing that poor sleep quality in healthy individuals is associated with a stronger biological response to a stressful challenge, such as the cold pressor test. This test involves the immersion of the hand in ice-cold water. It is one of the most commonly used laboratory physiological challenge tests, provoking not only unpleasantness, but also increases in stress and inflammatory markers.

Investigations of such system's reactivity to challenge may elucidate systems abnormalities that the investigators do not capture by only assessing basal system's levels. For example, in patients with rheumatoid arthritis, basal inflammatory levels are normal, but the response to a physiological stress challenge (cold pressor test) is amplified.

To the investigators knowledge, no studies have measured how insomnia may affect the reactivity of biological systems to a stressful challenge, which may serve as an important indicator of system's dysregulation and associated disease risk.

In this light, the primary goal of this proposal will investigate whether stress-related systems are more reactive to a physiological stressful challenge in insomnia disorder compared to healthy controls.