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Early chronotype with advanced activity rhythms and dim light melatonin onset in a rural population

Ruiz Da Silva, Francieli, Beijamini, Felipe, Beale, Andrew, Goncalves, Bruno da Silva B., Vartanian, Daniel, Taporoski, Tamara P., Middleton, Benita, Krieger, Jose E., Vallada, Homero, Arendt, Josephine , Pereira, Alexandre C., Knutson, Kristen L., Pedrazzoli, Mario and von Schantz, Malcolm (2020) Early chronotype with advanced activity rhythms and dim light melatonin onset in a rural population Journal of Pineal Research, e12675.

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Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affects the circadian clock under real-life conditions. We have previously described a strong tendency towards morningness in the Baependi Heart Study, located in a small rural town in Brazil. Here, we tested the hypothesis that this morningness tendency is associated with early circadian phase based on objective measurements (as determined by dim light melatonin onset, DLMO, and activity) and light exposure. We also analysed how well the previously collected chronotype questionnaire data was able to predict these DLMO values. The average DLMO observed in 73 participants (40 female) was 20:03±01:21, SD, with an earlier average onset in men (19:38±01:16) than in women (20:24±01:21; p≤0.01). However, men presented larger phase angle between DLMO and sleep onset time as measured by actigraphy (4.11 hours vs 3.16 hours; p≤0.01). Correlational analysis indicated associations between light exposure, activity rhythms, and DLMO, such that early DLMO was observed in participants with higher exposure to light, higher activity and earlier light exposure. The strongest significant predictor of DLMO was morningness-eveningness questionnaire (MEQ) (beta=-0.35, p≤0.05), followed by age(beta=-0.47, p≤0.01). Sex, light exposure, and variables derived from the Munich Chronotype Questionnaire were not significant predictors. Our observations demonstrate that both early sleep patterns and earlier circadian phase have been retained in this small rural town in spite of availability of electrification, in contrast to metropolitan post-industrial areas.

Item Type: Article
Divisions : Faculty of Health and Medical Sciences > School of Biosciences and Medicine
Authors :
Ruiz Da Silva,
Beijamini, Felipe
Beale, Andrew
Goncalves, Bruno da Silva B.
Vartanian, Daniel
Taporoski, Tamara P.
Middleton, Benita
Krieger, Jose E.
Vallada, Homero
Pereira, Alexandre C.
Knutson, Kristen L.
Pedrazzoli, Mario
von Schantz,
Date : 29 June 2020
Funders : Academy of Medical Sciences/Newton International Fellowship, CNPq, Fundação Zerbini and Hospital Samaritano,, National Institutes of Health, Institute of Advanced Studies of University of Surrey, FAPESP
DOI : 10.1111/jpi.12675
Grant Title : Academy of Medical Sciences/Newton International Fellowship
Copyright Disclaimer : © 2020 The Authors. Journal of Pineal Research published by John Wiley & Sons Ltd This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Uncontrolled Keywords : Actigraphy; Circadian rhythms; Neuroendocrinology; Phase angle, Sleep-wake rhythm
Depositing User : James Marshall
Date Deposited : 23 Jun 2020 10:59
Last Modified : 23 Jul 2020 07:26

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