Introduction: The PER3 VNTR polymorphism is an individual variability present in human and non-human primates that is functionally associated with sleep and circadian phenotype. Furthermore, the latitude where the subjects reside seems to be an important factor for synchronization, both photic and social, even more when we consider that we are increasingly deregulating sleep schedules due to demands at work, school or other factors. Considering that the concept of latitude reflects a set of characteristics that involve geophysical and climatic factors, it also seems to be related to sleep markers, such as daytime sleepiness. Objective: Thus, the objective of this work is to verify which interactions exist between the VNTR polymorphism of the PER3 gene and latitude-specific environmental markers in sleep parameters of young adults living in three different latitudes of the Brazilian territory. Method: The method used consisted of three stages, with Stage 1 referring to the use of the sociodemographic questionnaire, the Munich chronotype and the excessive daytime sleepiness scale. In step 2, the genotyping of cells from the oral mucosa was carried out via DNA extraction and classification of the subjects according to the VNTR polymorphism of the PER3 gene. The last step consisted of collecting variables related to latitude in three different cities with different latitudes: Maceió – AL, Campinas – SP and Porto Alegre – RS. The sample number was 702 participants, including only undergraduates who start classes between 07:30-08:00 in the morning. Subjects using medications that affect sleep and who had traveled across the country in the month prior to selection were excluded. After descriptive statistics, the Kruskal-Wallis (p-value <0.05 adopted for significance) was used as a basic test of inferential statistics. Results and discussion: We determined that young adults residing in high latitudes, compared to those living in low latitudes, have higher levels of social jet-lag, excessive daytime sleepiness and are more afternoon. Furthermore, the longest twilight durations, the longest photophase length, the greatest phase angle differences and the lowest mean solar irradiance were found in Porto Alegre, in absolute contrast to the findings in Maceió. Regarding the VNTR polymorphism of the PER3 gene, residents of Porto Alegre and with 4/4 polymorphism showed a sleep compensation on weekends, given the accumulated sleep deprivation during the week. Conclusions: This work provides us with details of sleep behavior and the synchronization process in young Brazilian adults living in different latitudes, representing geophysical and social particularities. Our findings may contribute to the understanding of genetic-behavioral and environmental factors that may explain the existence of high variability in health-disease processes.