Psychological stress is defined as a “state in which homeostasis is actually threatened or perceived to be so”, whereas homeostasis represents the complex and dynamic equilibrium between all systems functioning in a living organism [1, 2].

Adaptation is one of the core characteristics of living organisms, wherever it refers to proximate adjustments at individual level to inner or outer events, or to ultimate evolutionary processes at species-level.

Some stress protocols show a pro-inflammatory response in the brain and other systems characterized by a complex release of several inflammatory mediators such as cytokines, transcription factors, prostanoids and free radicals.

Chronic stress can be an extremely detrimental phenomenon because it maintains an artificial state of excitation, whereas acute stress ends this process in a more timely manner.

Accumulated evidence from animal models suggests that exogenously applied stress enhances airway reactivity and increases airway inflammation.