TLDR An individual's morning or evening preference can predict changes in their body clock gene expression.
The 2015 study "Diurnal Preference Predicts Phase Differences in Expression of Human Peripheral Circadian Clock Genes" involved 36 individuals, 14 of whom were extreme morning or evening chronotypes. The research used a novel method of extracting RNA from human hair follicles to measure the expression of two key clock genes, Per3 and Nr1d2. The findings indicated a significant phase shift in the oscillation of these genes between morning and evening chronotypes, with an average phase difference of 2.86 hours. This suggests that an individual's diurnal preference can predict differences in the expression of their circadian clock genes. The study also found that Morningness-Eveningness Questionnaire (MEQ) scores were significantly correlated with phase differences. The research concluded that analysis of Per3 and Nr1d2 mRNA levels from hair follicle cells provides valuable markers for estimating peripheral clock oscillations in human behavioral studies.
15 citations
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October 2012 in “Journal of circadian rhythms” RNA from horse hair follicles can track circadian rhythms non-invasively.
38 citations
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August 2012 in “Biochemical and biophysical research communications” Human leukocytes and beard hair follicle cells have internal daily clocks, and PER1 and PER3 genes may indicate individual circadian rhythms.
166 citations
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August 2010 in “Proceedings of the National Academy of Sciences of the United States of America” Scientists found a new, less invasive way to study body clocks using hair cells, which shows shift workers' body clocks don't match their lifestyles.
29 citations
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January 2014 in “Frontiers in physiology” Understanding and tracking our body's natural daily rhythms could help improve heart health.
14 citations
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June 2016 in “Hypertension research” New method uses hair follicle cells to estimate human body clock phase, potentially improving sleep disorder diagnosis.
15 citations
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October 2012 in “Journal of circadian rhythms” RNA from horse hair follicles can track circadian rhythms non-invasively.
4 citations
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May 2021 in “Lasers in Surgery and Medicine” Light therapy reduces scalp inflammation, boosts hair regrowth with Minoxidil 2%.
36 citations
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July 2016 in “Scientific reports” People's decision-making can be influenced by their internal biological clocks, as shown by gene expression, not just self-reported preferences for morning or evening.
