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Updated: Dec 17, 2025

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Environmental temperature as a mediator on the association between photoperiod at birth and chronotype
Renata Costa Santos1, Aline Cristina Pereira E Silva2, Maria José Dos Santos3
1Circadian Medicine Center, Faculty of Medicine, Federal University of Alagoas , Maceió, Brazil.
Abstract:
The association between chronotypes and season of birth (SOB) remains an inconclusive issue due, in some extension, to the lack of investigations of mediation mechanisms. We evaluated the association of photoperiod at birth (PAB) with chronotypes and sleep duration in Brazil (n = 810), and the mediating effect of meteorological factors, sex, age and rs4753426 polymorphism in the melatonin receptor MTNR1B. Longer PAB was associated with a delayed mid-sleep phase with a suppressive effect of maximum environmental temperature. No significant interactions were identified for the other variables. These findings suggest that photoperiod and environmental temperature modulate chronotype development at early stages.
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