It is normal for the body temperature in the afternoon to be within 1℃ higher than that in the morning. The body temperature of human is not constant, and it fluctuates within a certain range throughout the day due to the difference in the amount of activity and heat production of the body. In the morning, when people wake up, the amount of activity is small, the energy consumption of the body is small, and the heat production of the body is relatively small, so the body temperature is relatively low. On the contrary, in the afternoon, as people’s activities increase, the body’s heat production increases, resulting in a higher body temperature than in the morning. After the evening, as people’s activities decrease, the body’s heat production effect tends to balance, and the body temperature gradually drops. Therefore, the body temperature in the morning is the lowest, and the body temperature in the afternoon and evening is the highest, due to the self-regulation of body temperature, the difference between the two will not exceed 1 ℃, if the difference in body temperature more than 1 ℃ in a day is not normal, you need to carefully find the cause.