Association between social jet lag, quality of diet and obesity by diurnal preference in Finnish adult population

ABSTRACT

The evening type has been associated with unhealthy behaviors and adverse health outcomes, such as unhealthy dietary habits and obesity. Misalignment between biological and social rhythms, referred to as social jet lag (SJL), has been considered to explain these outcomes, because evening types are more prone to SJL. However, the existing evidence has been inconsistent and SJL by diurnal preference has hardly been examined. We examined the associations between SJL, the quality of the diet, and the prevalence of obesity by diurnal preference. This dataset included 6779 Finns (55% women, aged 25–74 years) from the National FINRISK 2012 and DILGOM 2014 studies. Diurnal preference was assessed with a shortened version of the Morningness-Eveningness Questionnaire (MEQ). SJL was calculated with the sleep-corrected formula (SJL_sc). SJL was divided into three groups by the degree of SJL (<1h, ≥1h but <2h and ≥2h). The dietary intake was assessed with a validated food frequency questionnaire (FFQ) and the quality of the diet with the Baltic Sea Diet Score. Body weight, height, and waist circumference (WC) were measured, and the body mass index (BMI) was calculated (kg/m²). Analysis of covariance (ANCOVA) followed by Bonferroni multiple comparison post-hoc tests and logistic regression models were used to analyze the differences between the lowest and the highest SJL groups by diurnal preference. In the highest SJL group (≥2h), there were more evening types than morning types (7%-points, p < .001). Overall, those in the highest SJL_sc group were on average younger than those in the lowest SJL_sc group (p< .001). Also, those in the highest SJL_sc group tended to have lower adherence to the Baltic Sea Diet compared to the participants in the lowest SJL_sc group, but this difference reached significance only in morning types (p = .006). Furthermore, morning types in the highest SJL_sc group had higher BMI and WC compared to the morning types in the lowest SJL_sc group (BMI, p = .016; WC, p = .012). In conclusion, evening types had on average more SJL than morning types, but the degree of SJL was associated with the quality of the diet and obesity only in the morning types.

KEYWORDS:

• Chronotype
• diurnal preference
• social jet lag
• diet quality
• dietary index
• baltic sea diet score
• obesity
• morningness-eveningness

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This study was supported by the scholarship from the University of Helsinki, Fund for Agriculture and Forestry Sciences;University of Helsinki [1117946];