can occur... Using the balance between energy input and expenditure as the basis for applying the concept of allostasis, two types of allostatic overload have been proposed.Sterling (2020) proposed several interrelated points that constitute the allostasis model: Animals are designed to be efficient. Efficiency requires a brain to predict what will be needed and avoid costly errors. The brain further enhances efficiency by prioritizing needs and enforcing trade-offs. All systems, including the brain, organ systems, and single cells are designed for a particular operating range. (Example, cone photoreceptors adapt for daylight, and rod photoreceptors adapt for moonlight and starlight). A system's parameters vary according to predicted demand and adapt their sensitivities. While a wide range denotes a flexible and healthy system, when their evolved operating ranges are chronically exceeded, systems at all levels break down. Sterling (2004) proposed six interrelated principles that underlie allostasis: Organisms are designed to be efficient. Efficiency requires reciprocal trade-offs. Efficiency also requires being able to predict future needs. Such prediction requires each sensor to adapt to the expected range of input. Prediction also demands that each effector adapt its output to the expected range of demand. Predictive regulation depends on behavior whilst neural mechanisms also adapt. Mechanisms Allostasis emphasizes that regulation must be efficient, whereas homeostasis makes no reference to efficiency. In addition, allostasis recognizes that efficiency requires predicting bodily needs to prevent errors, whereas homeostasis emphasizes detecting errors and correcting them – responding like a thermostat. Prediction requires the brain to: (i) collect information across all spatial and temporal scales; (ii) analyze, integrate, and decide what will be needed; (iii) exert feedforward control of all parameters. Naturally, many needs are somewhat unpredictable, so errors are inevitable; and for those errors, homeostatic mechanisms – feedback control – are available to correct them. Allostatic (predictive) regulation allows the brain to prioritize needs, for example, by sending more oxygen and nutrients to organs that need it most. For this example, during peak exercise muscle requires an 18-fold increase in oxygenated blood, but the heart can increase its capacity only 3.5-fold. Therefore, the brain temporarily borrows blood from the digestive system and kidney rerouting it to muscle. It later repays the debt when muscle's increased need subsides. Without the ability to prioritize trade-offs between organ systems, the heart and lungs would need to be far larger while much of this costly extra capacity would go unused. Predictive regulation