What is the Origin of Systemic Power Down?

This concept is a biological interpretation of energy conservation principles, particularly relevant in the context of evolutionary biology and states of prolonged energy restriction or chronic illness. It is a more severe expression of the adaptive thermogenesis seen during caloric restriction. The "power down" metaphor emphasizes the global, integrated nature of this physiological slowdown.

What is the Mechanism of Systemic Power Down?

Hormonal signals of energy scarcity, such as low T3 (triiodothyronine) and leptin, and high reverse T3, trigger a central hypothalamic response to downregulate the thyroid axis and sympathetic nervous system activity. This neuroendocrine shift reduces whole-body oxygen consumption and cellular energy expenditure. The mechanism ensures survival by minimizing the daily caloric burn, but it severely compromises vitality and long-term health.

Systemic Power Down ∞ Area

Systemic Power Down

Meaning

Systemic Power Down is the coordinated, adaptive reduction in basal metabolic rate, non-essential physical activity, and cognitive function initiated by the body in response to a perceived or actual state of severe energy deficit or chronic threat. This is a profound, protective energy-saving strategy designed to conserve finite resources for core survival functions. Clinically, it presents as unexplained fatigue, lethargy, and a blunted stress response.