Allostasis

What is allostasis?

Allostasis describes how the body maintains stability by adjusting to changing demands. Preparing for a challenge can involve changes in hormones, cardiovascular activity, and immune function.

How it works

McEwen (1998) used the term allostatic load for the cumulative burden that can develop when these systems are repeatedly activated or poorly regulated. A response that helps in the moment can carry costs when the pattern continues.

A persistently stressful job, for example, could contribute to repeated stress responses and disrupted sleep. The details vary. Chronic stress does not produce one universal cortisol pattern, and understanding someone’s physiological burden requires more than knowing their job title.

Why it matters

The concept connects adaptation with its possible long-term costs. It directs attention to both the demands people face and how their bodies respond, rather than treating stress-related illness as inevitable.

Allostasis is often contrasted with homeostasis, but homeostasis is also dynamic. Billman (2020) explains why homeostatic regulation should not be reduced to returning everything to one fixed setting.