TY - JOUR
T1 - Early chronotype with advanced activity rhythms and dim light melatonin onset in a rural population
AU - Ruiz, Francieli S.
AU - Beijamini, Felipe
AU - Beale, Andrew D.
AU - Gonçalves, Bruno da Silva B.
AU - Vartanian, Daniel
AU - Taporoski, Tâmara P.
AU - Middleton, Benita
AU - Krieger, José E.
AU - Vallada, Homero
AU - Arendt, Josephine
AU - Pereira, Alexandre C.
AU - Knutson, Kristen L.
AU - Pedrazzoli, Mario
AU - von Schantz, Malcolm
N1 - The authors are thankful to the Municipal Council of Baependi for logistical support and assistance with fieldwork, the dedicated staff at the field station and the population of Baependi for their participation in the Baependi Heart Study. This study was supported by awards from the Academy of Medical Sciences/Newton International Fellowship to F Ruiz (NIF004\1030), from CNPq to H Vallada (400791/2015‐5), from FAPESP to AC Pereira, JE Krieger and M Pedrazzoli (grants 2007/58150‐7, 2010/51010‐8, 2013/17368‐0), from Fundação Zerbini and Hospital Samaritano, by the Global Innovation Initiative to M von Schantz (jointly funded by the British Council and the UK Department of Business and Skills), by the National Institutes of Health (R01HL 141881), and from the Institute of Advanced Studies of University of Surrey for F Beijamini.
Funding Information:
The authors are thankful to the Municipal Council of Baependi for logistical support and assistance with fieldwork, the dedicated staff at the field station and the population of Baependi for their participation in the Baependi Heart Study. This study was supported by awards from the Academy of Medical Sciences/Newton International Fellowship to F Ruiz (NIF004\1030), from CNPq to H Vallada (400791/2015-5), from FAPESP to AC Pereira, JE Krieger and M Pedrazzoli (grants 2007/58150-7, 2010/51010-8, 2013/17368-0), from Fundacion Zerbini and Hospital Samaritano, by the Global Innovation Initiative to M von Schantz (jointly funded by the British Council and the UK Department of Business and Skills), by the National Institutes of Health (R01HL 141881), and from the Institute of Advanced Studies of University of Surrey for F Beijamini.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affect 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 were 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 ≤.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 ≤.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 ≤.05), followed by age (beta = −0.47, P ≤.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 postindustrial areas.
AB - Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affect 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 were 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 ≤.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 ≤.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 ≤.05), followed by age (beta = −0.47, P ≤.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 postindustrial areas.
KW - actigraphy
KW - circadian rhythms
KW - neuroendocrinology
KW - phase angle
KW - sleep-wake rhythm
UR - http://www.scopus.com/inward/record.url?scp=85088153932&partnerID=8YFLogxK
U2 - 10.1111/jpi.12675
DO - 10.1111/jpi.12675
M3 - Article
C2 - 32598502
AN - SCOPUS:85088153932
SN - 0742-3098
VL - 69
JO - Journal of Pineal Research
JF - Journal of Pineal Research
IS - 3
M1 - e12675
ER -
