Researchers have generated the first comprehensive 4D maps of brain temperatures in healthy individuals, showing levels far higher than previously assumed—averaging 38.5°C—and varying by time of day and region.
For millennia, abnormal body temperature has signaled illness, with patterns offering key diagnostic clues, like disrupted circadian rhythms or localized heat from injury or infection.
Direct brain temperature measurements are rare due to their invasive nature. Most data comes from critically ill patients under continuous monitoring. Until now, brain temperature was assumed to mirror core body temperature—a misconception debunked by new research published in the journal Brain.
Advances in noninvasive imaging have revolutionized this field. Scientists from the MRC Laboratory of Molecular Biology (UK) analyzed data from critical care patients with traumatic brain injuries and healthy volunteers, capturing temperatures across morning, afternoon, and evening.
Strikingly, both groups averaged around 38.5°C in the brain—consistently higher than oral body temperatures.
Readings showed significant variability: cooler at night, hotter in deep brain structures (exceeding 40°C) versus surface areas. Women and older adults also exhibited elevated temperatures.
These findings challenge assumptions that elevated brain heat signals severe risk. Even peaks of 40.9°C appeared in healthy subjects, with no clear survival link in patients. Instead, disrupted daily temperature rhythms—failing to drop at night or rise appropriately—proved more predictive of poor outcomes, warranting further investigation.
