Human organism is able to adapt to extreme external conditions. Among other reasons, this characteristic has enabled humans to flourish on Earth. We are generally able to fight cold, but in some conditions this defence proves inefficient. And even though our knowledge of hypothermia is constantly becoming more comprehensive, many doubts, myths and understatements pertaining to this phenomenon persist. We would like to make an attempt here to clarify some of them.

Hypothermia and “freezing with cold” are not the same thing

Common “freezing with cold” means exposure to cold, but it does not necessarily mean lowering of core body temperature. We speak of hypothermia when temperature of internal organs of the body drops below 35°C (Table 1). If a cause of drop in temperature is a simple disproportion between heat generation and loss, we speak about “accidental hypothermia.” If hypothermia is caused by body trauma, we speak about “post-traumatic hypothermia.” It is worth noting that post-traumatic hypothermia varies in many ways from accidental hypothermia, and different temperature thresholds are assigned to both types of the disorder (Table 1) [1, 2].

Cold “creeps in” however it can

From a physical point of view, warmth may equally stand for both quantity as well as a form of internal energy transmission in a system [3]. If we say that an object is warm, it means it has a higher internal energy than the environment. So is the other way round: an object described as cold has lower internal energy. The process of heat transferral occurs between systems (bodies) of different temperatures – from the warmer system (of higher energy) to colder one (of lower energy). Hence, it is not the cold that “creeps in” but the warmth that “escapes.”

Human beings lose most of their heat by radiating it outside

Human body dissipates heat by four processes: radiation, convection, conduction, and evaporation. In a closed room, with minimal air movement, and in standard room temperature (21°C), an undressed human indeed loses most of his/her heat (about 55%) as infrared radiation [4, 5].