Sleeping behavior in the hair recognizable

The sleeping behavior is recognizable by the hair. An analysis of individual genes reveals whether humans are, for example, early risers or late sleepers.

(24.08.2010) Does the inner clock also tick in your hair? Not quite, but the sleep behavior of humans is also recognizable by an analysis of individual genes in the hair. To this result, Japanese scientists have come in a series of experiments. Through the study results, the researchers hope to gain more knowledge for the treatment of sleep problems and sleep disorders. Such so-called clock genes are already known to researchers for more than ten years. It has also been known for some time that a permanent disturbance of the internal clock leads to illnesses.

Scientists led by study leader Makoto Akashi from Yamaguchi University in Japan examined so-called clock genes in the follicle cells of ruptured hair, which play a role in the control of the human's internal clock. The researchers found that in the subjects who get up early, the earliest activity of the individual genes are detectable. For workers and employees who work in weekly shifts, the phases in which the clock genes are read in relation to waking phases were shifted on average by 5 hours.

The internal clock, which is controlled by clock genes, has been scientifically proven for more than ten years. The internal clock specifies the functions and the tact of the organs. The biological clock of humans governs u.a. the storage of energy and its utilization in a "cyclical rhythm". In doing so, the human organism is oriented i.a. to external circumstances such as day and night. The "internal clock" is regulated in the brain by the "suprachiasmatic nucleus". Most people know a disturbance of the internal clock by a "jet lag". This causes the organs to „wrong time“ is activated when there are time-varying differences. This in turn leads to symptoms and complaints. Such "clocks" exist not only in the brain, but also in other parts of the human body. Biological clocks exist in the brain, liver, lung, heart, kidney and pancreas.

Shift workers are particularly affected by a disruption of the clock. Here the clock changes almost weekly. If the body has just stabilized on the new clock, then this has to orient itself again at the next shift change. Shift workers therefore show an increased risk of illness. In industrialized countries, the internal clock gets more and more out of sync. For example, artificial light in offices causes the day and night feeling disturbed.

During the course of the study, scientists collected hair every three hours from a total of four subjects. They took hair from their hair and beard hair. The study participants had previously been adjusted to a regular daily routine. If the participants had thick hair, five hairs were enough to clearly measure the activity of the genes. For those who had fine hair, at least 20 hairs were necessary. So far, scientists had the gene activities u.a. in skin cells taken from a biopsy.

However, the study mainly focused on shiftworkers. The same series of experiments was also applied to shiftworkers who work alternately in the morning and late shifts. But the activities of the genes in the course of the day in these subjects were very changeable and unstructured. One of the genes, the Per3 gene, was the most active in the study participants with a regular rhythm about one hour before waking up. For shift workers working in the morning shift, the gene was most active for an hour after getting up.

Shift work is therefore hazardous to health. Shift workers are more likely to suffer from sleep disorders, metabolic disorders, diabetes, cardiovascular disease and cancer. But a general statement that all shiftworkers are equally affected, can not be made. The body of the individual develops different tolerances. Many "inner clocks" adapt well to the different ways of life, others not at all. Why this is so different, can not be said clearly today. (Sb)

Swell:
In: PNAS 10.1073 / pnas.1003878107, 2010. and
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