Why does the temperature rise to 37°C every night?

A body temperature of 37℃ at night may be a normal phenomenon, or it could be caused by conditions such as pneumonia or tuberculosis. The specific analysis is as follows:

1. Normal phenomenon

Body temperature naturally fluctuates throughout the day. It tends to be lower in the early morning, gradually rises after waking up, and may reach its highest levels from noon to afternoon. However, the variation within 24 hours is usually small, generally not exceeding 1℃. After eating in the evening or being in a warm environment, body temperature may rise slightly and remain around 37℃, which is considered normal and does not require treatment.

2. Pneumonia

If the body temperature reaches 37℃ at night without any noticeable symptoms, a lung infection such as pneumonia cannot be ruled out. A temperature of 37℃ might not be accompanied by obvious symptoms—especially in elderly individuals or those with weakened immune systems who develop pneumonia. In the early stages, they may show no symptoms and have no fever, with body temperature only around 37℃. Treatment under medical guidance with antibiotics such as cefixime dispersible tablets or amoxicillin capsules may be necessary.

3. Tuberculosis

If a nighttime temperature of 37℃ is accompanied by symptoms such as fatigue, weight loss, or if tuberculous lesions are found upon examination, it may indicate pulmonary tuberculosis. Treatment should follow a doctor’s advice and typically includes medications such as rifampicin capsules, isoniazid tablets, and pyrazinamide tablets.

Besides the common causes mentioned above, other possible reasons include lung tumors or rheumatic fever. It is recommended to seek prompt medical evaluation at a hospital for accurate diagnosis and appropriate treatment based on the underlying cause.