Our biological response to external challenges frequently obeys hormetic principles. During the phenomenon of hormesis, mild stressful challenges may upregulate defence and repair pathways, with a subsequent overall improvement in function. It is important to highlight that hormesis is a dose-response, non-linear phenomenon, meaning that a low dose of a stressor can result in benefit whereas a higher dose may result in damage. Hormesis is invoked when the challenge is of sufficient magnitude and appropriate quality as to satisfy the definition of ‘novelty’. Routine and monotony do not, as a rule, invoke a hormetic response. In this chapter I will discuss certain characteristics of hormesis as applied to humans, and examine several situations whereby an adequately-timed stimulus may be of practical health benefit. The assessment and response to the new challenge leads to adaptation and thus, eventually, improvement of function within a particular environment (the environment where the challenges have originated from). In this way, there is a direct link between external challenging information and internal physical or biological changes. This link will be explored in detail, both in this chapter and in other chapters of this book.
Keywords: Adaptation, Cellular networks, Exploratory behaviour, Homeodynamic space, Hormesis, Non-linearity, Novelty, Physical challenges, Power law, Stress response, Stressor, Stimulation