Genetic Characteristics May do not Track the Circadian Preference of a Shiftwork Brazillian Population - What is the Better Indicator

Introduction: The Period 3 (Per3) gene is associated with individual differences in several sleep and circadian functions. Shift workers experience sleep restriction and exposure to wakefulness during an adverse circadian phase. Workers who carry genetic polymorphisms in the Per3 gene may experience particularly high levels of sleepiness during the night shift, which can lead to the development of various diseases. They may also be at greater risk for automotive or occupational accidents when assigned to work hours that do not align with their chronotype profile. We hypothesize that the Morningness and Eveningness Questionnaire, also known as the AutoMEQ, developed by Horne and Östberg in 1976 (HO), may not be sufficient for defining work schedules in companies. It would, therefore, be necessary to include the evaluation of Per3 gene polymorphism to make more accurate decisions.

Methods: Our study aimed to investigate the genetic profile of night and shift workers, as well as whether they present differences between the circadian preference results from the HO questionnaire and their genetic chronotype. For this study, DNA extracted from archived buccal cell samples was obtained from randomly selected subjects participating in the Brazilian mining companies, average age 43.7 years, and we applied a validated MEQ containing 19 questions about the sleep and activity preferences by Horne and Ostberg 1976, Brazilian version. Chronotype was assessed according to the formula provided in the instruction for MEQ score interpretation.

Results: We detected significant discrepancies in the HO questionnaire when compared with the genetic results of workers, especially among 1.9% of workers who self- identified as evening types according to the HO questionnaire but had a genetic chronotype of 38.1% classified as eveningness. Unexpectedly, 77.9% of workers reported being morning types, which agreed with their genetic profile in only 12.1% of cases.

Conclusion: Our data serves as a warning for companies to assess the genetic profiles of their employees to avoid misinterpretations regarding circadian preference, which could contribute to poor work performance, harm worker health, and increase the risk of accidents. Support: UFMG, UNIFESP, FEPE, CEPE, CEMSA, CAPES, CNPq.

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Artikel online veröffentlicht:
08. Oktober 2025