Normal body temperature has long been considered to be around 98.6°F (37°C), a standard that has been in place for over 150 years. However, recent research indicates that this average has been gradually declining. For instance, a study found that the average body temperature of 96 adults over two weeks varied from 95.4°F (35.2°C) to 99.3°F (37.4°C). This suggests that there is a wide variation in normal body temperatures and knowing your own baseline can be beneficial.

Moreover, an analysis of 20 studies published between 1935 and 1999 indicated an average oral temperature of 97.5°F. This was echoed by a 2023 study and an earlier study which included more than 35,000 people, pinpointing the average body temperature at 97.9°F.

Researchers from Stanford University have determined that the average human body temperature in the United States has indeed decreased since the 1800s. This challenges the long-standing notion of the “normal” human temperature of 37 degrees Celsius (or 98.6 degrees Fahrenheit), suggesting that it might be set too high.

Feeling cold all the time can be attributed to various factors such as low body weight, significant weight loss, or having a naturally slender build. Fat and muscle mass are important for heat retention as muscle activity generates heat and fat serves as insulation. Additionally, conditions like hypothyroidism, diabetes, liver or kidney failure, infection, endocrine dysfunction, or the side effects of certain medications can also cause a lower body temperature.

Hypothermia is a serious condition that occurs when body temperature drops below 95°F (35°C). While most common in extremely cold temperatures, hypothermia can also occur in cool temperatures above 40°F (4°C), especially if the person is wet from rain or sweat. Older adults are particularly at risk for hypothermia, even from prolonged exposure to mild cold.

Maintaining our internal body temperature within a range of 98.6°F, give or take a few degrees, is essential for optimal bodily functions. Deviations in internal temperature, whether caused by stress, exercise, or exposure to varying temperatures, can affect our health.

Therefore, it may be time to redefine what we consider normal body temperature, taking into account the individual variations and the overall decrease in average temperatures over the years. It is essential to understand your body’s normal temperature and to be aware of how conditions, both internal and external, can affect it.