The temperature of the human body is controlled. This means that the body is constantly making efforts to heat or cool itself so as to ensure that the temperature is maintained around 98 degrees Fahrenheit. The body functions most efficiently at temperatures around 98 degrees. The process of metabolism is used to produce heat in the body. Heat production is actually a side effect of the process of metabolism itself. This heat is then transported around the body in the blood which is also used as a device for thermoregulation. When heat needs to be eliminated from the body, the blood vessels dilate, allowing the flow of blood to the extremities of the body. From here, dissipation of heat takes place.
The body temperature throughout the day would vary depending on various aspects. An individual would normally wake up with a cool body temperature because the body is rested. However, this temperature will be slightly higher than the temperature at around 3 or 4 am. As the individual wakes up and begins his or her day, the body temperature will rise back to 98.6 degrees Fahrenheit or thereabout. The body temperature throughout the day depends on the amount of physical activity that the individual will undertake during the day. The environmental conditions also play a part in determining the temperature of the body. In extreme cold or hot conditions the individual's body will change its temperature as well. This change is not controlled by the body. It is, instead, a function of the transfer of heat to or from the body because of the temperature difference between the individual and the environment. See also low body temperature at night
If there is elevated body temperature throughout the day, the patient is suffering from fever. Fever throughout the day is the sign of some infection or condition in the body. The body heats up to try and kill the infection and will not cool down until the problem has passed. An individual should not be concerned if the body temperature throughout the day fluctuates slightly. Wild fluctuations are a sign of some medical condition and must be reported to a doctor.
Heat production is a function of the rate of metabolism in the body. Therefore, an individual's body will be hot when physical activity is taking place. This is because physical activity demands energy and energy, as explained above, is produced during the process of metabolism. Therefore, an individual will naturally have a lot of heat generated in the body during exercise. This is why people tend to sweat, even in cold climates, when they are exercising.