Researchers have shown how the brain’s circadian rhythm in rats is, among other things, controlled by the stress hormone corticosterone — in humans called cortisol. This has been shown by means of a completely new method in the form of implanted micropumps.

This internal clock is found in everything from bacteria to humans and is controlled by some very distinct hereditary genes, known as clock genes.

In the brain, clock genes are particularly active in the so-called suprachiasmatic nucleus. It sits just above the point where the optic nerves cross and sends signals to the brain about the surrounding light level. From here, the suprachiasmatic nucleus regulates the rhythm of a number of other areas of the body, including the cerebellum and the cerebral cortex.

However, these three areas of the brain are not directly linked by neurons, and this made researchers at the University of Copenhagen curious. Using test rats, they have now demonstrated that the circadian rhythm is controlled by means of signalling agents in the blood, such as the stress hormone corticosterone.

‘In humans, the hormone is known as cortisol, and although the sleep rhythm in rats is the opposite of ours, we basically have the same hormonal system’, says Associate Professor Martin Fredensborg Rath of the Department of Neuroscience.

He explains that recent years have seen an increasing, scientific focus on research on clock genes, one reason being that previous research on clock genes have found a correlation between depression and irregularities in the body’s circadian rhythms.

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Materials provided by University of Copenhagen The Faculty of Health and Medical Sciences. Note: Content may be edited for style and length.