Saturday, September 1, 2012

Body temperature instructs the biological clock

Our body is full of biological clocks, although most people are only familiar with one of them: the sleep-wake cycle that lasts around 24 hours. It makes us feel tired in the evening and active during the day, and it is closely related to the patterns of sunlight we get daily. In order to instruct this biological cycle pattern, a network of proteins is needed that responds to external cues, such as the aforementioned sunlight. Scientists discovered that temperature is also an important factor governing our sleep-wake cycle.

Body temperature varies during the day and is usually lower in the morning and higher in the evening. In the lab, researchers working at the University of Geneva set up experiments with cultures of human cells, to which they applied a simulated daily rhythm in temperature variations. By doing that, they were able to show that temperature is closely correlated to the production of something called 'Cold induced RNA-binding protein', a name that accurately describes the scientists' findings. It's relation with temperature was already known, but its function in the body's circadian clock was not.

In addition to showing that the pattern of CIRP expression follows the fluctuations in daily body temperature, the researchers managed to show that losing production of this particular protein impacts the production of other proteins as well. Experiments with CIRP depletion showed that various components of the circadian body clock were consequently produced in lesser quantity. This includes production of a protein called Clock, which, perhaps not surprisingly, is one of the most important proteins in governing the sleep-wake cycle. It basically activates a cascade of reactions that make up our daily rhythm.

According to the scientists, the effects of body temperature on CIRP and consequently on the circadian body clock is a way to offer robustness. Because other 'oscillators' affecting our daily rhythm, such as sunlight, can fluctuate to a great extent, other factors such as the variation in body temperature keep the clock somewhat steady. It is interesting to dive deeper into this topic, and find out how external temperatures affect our circadian cycle: perhaps modifying the external temperature can help us to adjust the body clock somewhat to our preferences, though this is pure speculation. Because people often say that feeling cold makes them feel sleepy, it may have something to do with a reduction in CIRP.

We continue to learn more about how clocks affect our bodily functions. An overview of the things that happen can be found below, but there are also studies being performed in order to elucidate how this all works. Recently, researchers showed that we possess a gene that is tasked with waking us up. The biological clocks may also be a cause of a metabolic disorder, indicating that studies in this field, called chronobiology, can also help us find new ways to treat diseases.
An overview of how the time of day affects physiology, due to the effects of various internal clocks.

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