McEwen and Wingfield propose two types of<unk>  with different etiologies and distinct consequences:- Type 1<unk>  occurs when energy demand exceeds supply, resulting in activation of the emergency life history stage. This serves to direct the animal away from normal life history stages into a survival mode that decreases<unk>  and regains positive energy balance. The normal life cycle can be resumed when the perturbation has passed. Typical situations ending up in type 1 allostasis are starvation, hibernation and critical illness. Of note, the life-threatening consequences of critical illness may be both cause and consequences of<unk> . Type 2<unk>  results from sufficient or even excess energy consumption being accompanied by social conflict or other types of social dysfunction. The latter is the case in human society and certain situations affecting animals in captivity. In all cases, secretion of glucocorticosteroids and activity of other mediators of allostasis such as the autonomic nervous system, CNS neurotransmitters, and inflammatory cytokines wax and wane with<unk> . If<unk>  is chronically high, then pathologies may develop. Type 2<unk>  overload does not trigger an escape response, and can only be counteracted through learning and changes in the social structure. Whereas both types of<unk>  are associated with increased release of cortisol and catecholamines, they differentially affect thyroid homeostasis: Concentrations of the thyroid hormone triiodothyronine are decreased in type 1 allostasis, but elevated in type 2 allostasis. This may result from an interaction of type 2<unk>  with the set point of thyroid function. Special situations may involve a blend of both type 1 and type 2<unk> . Examples include exhausting excercise and adpatation to antarctic conditions.
Allostatic load
Stress shielding
Surgical stress
Stress 
Chronic stress
Tissue stress
Pressure overload
Overtraining