Variations in normal body temperature
Temperature control is a normal process in the human body by which an organism keeps the optimum temperature in various circumstances. No person has exactly the same body temperature during the whole day. Body temperature is interestingly unstable and subject to change. Even a single individual may experience ups and downs in the average temperature reaching the 1.0 °F (0.5 °C) in amplitude.
The body temperature is lowest around 4 a.m. while reaching its peak in the late afternoon between 4:00 and 6:00 p.m. A gap between these measurements can measure about 1.0 °F. Women’s body temperature even fluctuates with the menstrual cycle, and it slightly rises after the ovulation. It is a basal body temperature that changes here, defined as the lowest temperature attained by the body during a rest.
Variations as a result of measurement methods
There are different methods for measuring body temperature. Typically, body temperature is measured under the armpit, but it can also be measured in the oral cavity or in a rectum. Oral temperatures are considered the most convenient type of temperature measurement, but they can be influenced by drinking, chewing, smoking, and breathing with the mouth open.
Axillary temperatures are result of measurements taken in the armpit or between the folds of the skin. This type of measurement lasts longer, and it is most inaccurate. In most of the cases, these skin-based temperatures do not report correctly about the core body temperature. They can also be influenced by external factors such as clothing and air temperature.
Rectal measurements give values for internal body temperature, and they are the most accurate but very uncomfortable.