ABSTRACT
OBJECTIVE: Social jetlag is a discordance between the social and biological rhythm and is associated with higher HbA1c, higher BMI, and higher odds of obesity. The pathways that could explain these associations are still debated. This study aims to assess the mediating role of several lifestyle factors in the cross-sectional association between social jetlag and BMI. METHODS: We used cross-sectional data from 1784 adults from urban areas in the Netherlands, collected in 2019. Social jetlag (difference in midpoint of sleep between week and weekend nights) was categorized as low(<1 h), moderate(1-2h), and high(>2 h). BMI(kg/m2) was calculated from self-reported height and weight. The association between social jetlag and BMI was assessed using linear regression, adjusted for sex, age, education, and sleep duration and stratified for the effect modifier stress (high vs. low). Mediation analysis was performed for self-reported smoking, physical activity, alcohol consumption, and adherence to a healthy diet. RESULTS: High social jetlag was associated with higher BMI (0.69 kg/m2,95%CI 0.05;1.33). This association was stronger in people with high stress (0.93 kg/m2,95%CI 0.09;1.76). Social jetlag was also associated with higher odds of smoking, lower physical activity, higher alcohol consumption, and lower healthy diet adherence. In people with high stress, these factors mediated 10-15% of the association between social jetlag and BMI. CONCLUSIONS: Social jetlag is associated with higher BMI and this association is stronger in people with high stress. In people with high stress, healthy diet adherence mediated 12% of this association. Other pathways involved in this association should be further investigated.
ABSTRACT
Until now, no in vitro methods for determining neurotoxic effects, on Phase I and Phase II biotransformation-driven metabolite formation or for the evaluation of the metabolism-mediated hazard of a chemical, have been validated. The current test guidelines are based on studies in vivo, involving animals exposed to the test substance. Novel in vitro testing instead of animal testing is required by Directive 86/609/EEC. In the EU White Paper on a Strategy for a Future Chemicals Policy, which may result in up to 20,000 chemicals being screened for toxicity, the use of non-animal test methods is seen as essential and is encouraged. The aim of the present work was to demonstrate the significance of novel technologies, including the use of genetically engineered cell lines and three-dimensional cell culture techniques for direct application in the regulatory hazard-assessment process. Furthermore, attempts were made to make in vitro toxicity tests for specific applications more-readily available for inclusion in the chemical hazard-assessment process, by exploiting advances made in the life sciences.
