Evidências do efeito mediador da temperatura ambiental na associação entre fotoperíodo ao nascimento e cronotipo

Abstract

Circadian rhythms are cycles of approximately 24 hours, regulated by a central oscillator and controlled by external synchronizers, mainly influenced by light. The association between photoperiod at birth (PAB) and circadian rhythms has been reported in the literature, being the most common eveningness chronotype in the group of people born in months with longer photoperiods. In addition, the single nucleotide polymorphism (SNP) rs4753426 no promoter of the MTNR1B gene and the variable number tandem repeat polymorphism (VNTR) in the Per3 gene were associated with the chronotype and could modulate these associations. The objective of this study was to evaluate the association between photoperiod at birth and chronotypes and to investigate the possible mediating effect of meteorological variables and genetic polymorphisms. The Morning and Evening Questionnaire (MEQ) and the Monique Chronotype Questionnaire (MCTQ) were applied to determine the chronotype and sleep pattern in a sample of 810 young adults from the population of Alagoas. Subject genotyping was performed by PCR techniques for the Per3 SNP rs4753426 VNTR polymorphism in the MTNR1 gene promoter. Statistical analysis was performed in R programming environment. Consistent with the literature, we found an association between long PAB and eveningness. There was a negative mediating effect of ambient temperature on the relationship between PAB and chronotype. There was no mediating effect of polymorphisms in this association. These findings demonstrate that PAB can play an important role in chronotype development in the early stages of development. Considering the consistently reported association between eveningness and metabolic and behavioral dysfunctions, this data may help in the establishment of preventive measures in hospital or domestic environments during pregnancy or for neonates.