Biological clock: the hair test reveals your chronotype

Literally split hairs to accurately measure your internal biological clock. This is the principle from which a study by the Charité – Universitätsmedizin of Berlin published on starts Pnaswho developed a test based onanalysis of hair roots to determine the individual chronotype. The goal? Offer a practical tool to measure a person’s circadian rhythm and open the doors to medicine more in line with the biological times and needs of each individual.

Biological clock and circadian rhythms

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Circadian rhythms do much more than regulate the alternation between sleep and wakefulness. According to researchers, they also affect the metabolism, the functioning of the immune system and, consequently, the response to therapies. “For example”, he explains toAdnkronos Achim Kramer, head of the Division of Chronobiology in the Department of Anesthesiology and Intensive Care at the Charité, “studies show that the time of day in which some cancer immunotherapies are administered may have a substantial impact on their effectiveness“. And the reason for this phenomenon lies in the fact that the immune system, like most organs, also follows a cycle of approximately 24 hourswhich however varies from person to person and depends on a number of factors, including age, sex and lifestyle.

A new method for measuring chronotype

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Until now, to determine someone’s circadian rhythm, we used the measurement of melatonin in saliva, performed over several hours and in low light conditions. However, it is a complex procedure, very limiting and not scalable. The test developed by the Charité group, however, analyzes the activity of 17 genes within the cells of some hair follicles through artificial intelligence. According to researchers, all it takes is one single sampleall with a precision almost comparable to that of the standard melatonin system.

The new methodology was tested on over 4 thousand participants, who sent the necessary samples from home. And many of the correlations that emerged were already known. For example, people around the age of 25 tend to get tired on average about an hour.now later than those over 50. The study also found an average difference between the two sexes: in the women examined, the biological night begins 6 minutes earlier than in men (but the difference is lower than that indicated in questionnaire-based research). Finally, in employed subjects, the internal biological clock appears to activate on average about half an hour earlier compared to those who don’t work.