Maintaining body temperature

Most of the time adults are unaware of their body temperature because it usually remains at a constant, comfortable level. A special regulating centre in the brain, the hypothalamus, carefully balances the amount of heat produced and the amount lost by the body by, for example, making us sweat or shiver. Control of temperature in this way is part of maintaining homeostasis of the body. Adults are therefore referred to as being ‘homeothermic’, that is, able to maintain their core body temperature at a constant level regardless of the external temperature (see Figure 9.1). As can be seen their skin temperature can be several degrees higher or lower than the core temperature without affecting overall body function.

Figure 9.1 Variations in core and skin temperatures

In infants and children, however, the control centre is not fully developed. This therefore means that there is a potential for wide variations in body temperature; this is why it is crucial that parents or carers monitor constantly the temperature of infants and children and make adjustments to their clothing and environment on their behalf.

Normal body temperature is subject to variation over the 24-hour day, in keeping with the circadian rhythm (sometimes known as diurnal variation). It starts to rise at about 06.00 hours until 11.00 hours. After 11.00 hours it levels out until about 17.00 hours, by which time it may have risen 0.5–0.7ºC from early morning. It then starts to fall again in the early hours of the morning, when body temperature is at its lowest. This is why when we undertake night duty we usually feel quite cold around 03.00 hours and often feel the need to have a warm drink, eat or go for a walk round the ward or department.

The factors that may affect body temperature include:
• physical, for example illness, infection, gender, age, metabolic rate
• psychological such as emotion, stress and anxiety
• sociocultural including exercise, activity, recreational drugs
• environmental, for example time of day, severe heat or cold
• politico-economic, for instance lack of finances for heating or occupation.