柏林夏里特医学大学（Charité – University Medicine Berlin）的研究人员报告说，只要一份头发样本，特别是几根拔下来的发根，就能以令人惊讶的精确度揭示一个人的生理时钟在一天中的位置。这项由 Achim Kramer 教授及其同事领导的研究显示，医学可能会从依赖墙上的时钟，转向依照身体自身的日常节律来安排照护。

研究团队表示，头发根部留下的生物讯号可以被读作一种实用的身体时间测试，弥合了易于采集的样本与长期以来实验室的黄金标准之间的差距。这种标准方法一直是在严格控制的微弱光线下，于数小时内测量唾液中的褪黑激素，病人必须遵守严格的照明规则并反复提供唾液样本，这限制了它在常规情境中的使用，也使大规模研究变得困难。

关键含义是，如果一种基于头发的读出能取代繁琐的唾液流程，时间生物学与临床照护在大规模应用上可能会变得更容易。这篇文章没有提供样本数、准确率百分比或错误率，因此主要的定量重点是几根发根与数小时微弱光线下的唾液测试之间的对比，凸显出朝向更实用、也更以病人为友善的时序诊断的潜在转变。

Researchers at Charité – University Medicine Berlin reported that a single hair sample, specifically a few plucked hair roots, can reveal where a person's internal clock sits in the day with surprising precision. The work, led by Professor Achim Kramer and colleagues, suggests that medicine may move from relying on the wall clock to timing care around the body's own daily rhythms.

The team showed that the biological signal left in hair roots could be read as a practical test of body time, closing the gap between an easy-to-collect sample and the long-standing laboratory gold standard. That standard method has been melatonin measurement in saliva under carefully controlled dim light for several hours, with patients following strict lighting rules and giving repeated saliva samples, which has limited its use in routine settings and made large studies difficult.

The key implication is that chronobiology and clinical care may become easier to apply at scale if a hair-based readout can replace the cumbersome saliva protocol. The article does not provide sample size, accuracy percentages, or error rates, so the main quantitative point is the contrast between a few hair roots and several hours of dim-light saliva testing, highlighting a potential shift toward more practical and patient-friendly timing diagnostics.