DALLAS, Oct. 22 (UPI) -- Internal temperature regulates the body's clock -- circadian rhythm -- controlling sleep and other functions, U.S. researchers say.
Researchers at the University of Texas Southwestern Medical Center in Dallas found a light-sensitive portion of the brain acts as the body's "master clock" coordinating the daily 24-hour clock, but it does so indirectly.
The study, published in Science, found the brain responds to light entering the eye and transforms this information into neural signals that set the body's temperature. These cyclic fluctuations in temperature then set the timing of cells and ultimately the activity/inactivity of tissues and organs.
The researchers point out while long known that body temperature fluctuates in warm-blooded animals throughout the day on a 24-hour rhythm this study shows it is temperature that actually controls body cycles.
"Small changes in body temperature can send a powerful signal to the clocks in our bodies," Dr. Joseph Takahashi, the study's senior author, said in a statement. "It takes only a small change in internal body temperature to synchronize cellular 'clocks' throughout the body."
Takahashi explained daily changes in temperature span only a few degrees and this mechanism has nothing to do with fever or environmental temperature.
