allostasis: a standalone construct

Peter Sterling and Joseph Eyer coined the term allostasis in a 1988 chapter to name a specific idea: the body keeps itself stable by changing its internal settings ahead of demand, rather than defending a single fixed level. The word joins the Greek allo, meaning variable, to the root shared with homeostasis, the older concept in which the body corrects deviations to return each variable to a constant set point. Bruce McEwen's widely cited 1998 account carried the idea into stress physiology and neuroscience, treating allostasis as the active process by which the brain and hormonal systems adjust blood pressure, glucose, and other parameters to meet anticipated needs, and separating that adaptive effort from the cumulative cost of overusing it. Sterling later framed allostasis as predictive regulation, in which the system uses experience to forecast what will be needed and to set levels before an error occurs, so a rise in a measure is read as preparation rather than as a deviation to be corrected. As a construct it spans physiology, endocrinology, and behavioral neuroscience, and it is defined by its emphasis on anticipation and variability, which marks it apart from the equilibrium-restoring account of regulation it was proposed to extend.[1][2][3]

Unit

A regulatory process within an organism: the active adjustment of internal parameters to meet anticipated demand

Recovery means

Not applicable

Measured by

Studied through the anticipatory regulation of physiological parameters (for example cortisol, blood pressure, heart rate, and glucose) as they shift ahead of predicted demand; the cumulative cost of repeated allostasis is indexed separately as allostatic load