Much of our thinking about physiology, and its applications to medicine, is dominated by the concept of homeostasis, according to which key physiological variables are maintained at constant levels, typically through feedback mechanisms. Examples would certainly include body temperature, hormone levels, and serum ion concentrations. Disease is then seen as the failure of homeostatic mechanisms, leading to a “chemical imbalance”, and therapy is then the restoration of normal levels of the quantity in question.

The only problem with the doctrine of homeostasis is that it is false, indeed, wrong-headed. The quantities in question, including body temperature, hormone levels, ion concentrations, and gene expression levels, are not maintained at constant values. All of those quantities undergo significant oscillation, at a variety of time scales. Science and medicine have been highly reluctant to accept even the fact of these oscillations, let alone their functional significance.

We will discuss the presence of oscillatory processes in physiology (and chemistry), and discuss what mechanisms act to maintain and regulate these oscillations, and will also discuss their importance for a more advanced understanding of physiology and medicine.