Researchers have determined that a high degree of accuracy in pinpointing an individual’s internal body clock position can be achieved by examining just a single hair sample. This breakthrough holds the potential to make chronotherapy—medical treatments timed to align with a patient’s biological rhythms—accessible in standard clinical settings. The findings of this research have been documented in the journal Proceedings of the National Academy of Sciences.
Previously, the most reliable means of assessing biological timing involved measuring melatonin levels in saliva under conditions of heavily subdued lighting. This necessitated patients spending many hours in specially equipped labs, providing numerous samples sequentially—a process that, while precise, proved highly impractical for broad application. Professor Achim Kramer of Berlin’s Charité clinic explained, “The established protocol currently in use measures the concentration of melatonin, often termed the ‘darkness hormone,’ in saliva over several hours while light levels are kept very low.”
The novel technique developed by Kramer’s team relies on analyzing the expression of 17 specific genes within the cells of hair roots; only a few plucked hairs are required. A customized computational model, trained on this genetic data, is then employed to deduce the current phase of a person’s 24-hour circadian cycle. As stated by Kramer, “By leveraging machine learning, this established pattern can be utilized to calculate precisely where an individual stands within their daily rhythm at any given moment.” The efficacy of this method was validated across a cohort exceeding 4,000 participants who mailed their hair samples from home, as reported by Planet-today.ru.
This extensive data set uncovered some notable correlations. For individuals around 25 years of age, the internal ‘biological night’ commences approximately one hour later compared to those over 50, suggesting that the body’s internal clock drifts toward an earlier schedule with advancing age. Furthermore, employed individuals exhibited a circadian rhythm shift of roughly half an hour earlier when contrasted with those who are unemployed. Interestingly, the recorded disparity between the biological rhythms of men and women proved remarkably small—only about 6 minutes—despite earlier studies suggesting a much wider gap.
The practical implications of this methodology are substantial, given that the time of day directly impacts therapeutic efficacy. Existing evidence already indicates that cancer immunotherapy yields varying results across patients depending on the precise time of administration. A straightforward hair analysis could provide clinicians with the capability to determine the optimal window for prescribing medications. Currently, the research team is focused on standardizing the procedure so it can be implemented in conventional laboratories, as it still warrants further rigorous clinical validation.
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