Browsing by Subject "Vuorokausirytmi"

Introduction: Individual’s physiological functions and behavior are controlled by biological and social rhythms, as well light-dark-rhythm. The biological, intrinsic circadian rhythm is synchronized to follow the 24-hour day by external cues, mainly by light-dark-rhythm. Despite the synchronizing, there are inter-individual changes in this rhythm partly due the genetics. Chronotype expresses these differences and can vary from extreme morning type to extreme evening type. In addition, social rhythms, such as work schedules, control behavior as well. Sometimes these biological and social rhythms are not aligned causing social jet lag (SJL). From SJL can be distinguished two different phenomena; sleep debt caused by changes in sleep-awake-rhythm and the misalignment between biological and social rhythm without the effect of sleep debt. Especially evening types have been considered to suffer more of SJL and therefore, SJL has been thought to explain adverse health outcomes, such as obesity, and unhealthy behavior, such as poor quality of total diet, of evening types. However, the amount of previous studies considering the association between SJL and quality of the diet and prevalence of obesity of different chronotypes is scarce. Objectives: The objectives were to study the association between chronotype and SJL, as well the association between SJL and quality of the diet evaluated by Baltic Sea Diet Score and obesity by chronotypes in Finnish adult population. The purpose was also to study differences of two SJL formulas, of which are meant to distinguish the sleep debt and misalignment between biological and social rhythms. There are not previous studies to examine the differences between these two formulas. Methods: This study is a cross-sectional study based on two national population-based studies (FINRISK 2012, DILGOM 2014) which included 6779 men and women aged 25─74 years. Chronotype was evaluated by shortened Morningness-Eveningness Questionnaire (MEQ) and it was categorised into three group (morning, intermediate, evening). SJL was calculated by the original SJL formula and the sleep corrected SJL formula and was categorised into three groups by the degree of SJL (< 1h, ≥ 1h, < 2h and ≥ 2h). Participants’ habitual food consumption was evaluated by validated food frequency questionnaire (FFQ) and the quality of the diet by Baltic Sea Diet Score (BSDS). Body weight, height and waist circumference (WC) was measured by study personnel and BMI was calculated (kg/m2). Analysis of covariance (ANCOVA) followed by Bonferroni multiple comparison post hoc test and logistic regression were used to analyse the differences between the lowest (< 1h) and the highest (≥ 2h) SJL groups by chronotypes. Results: Among evening types were more participants in the SJL-group of at least 2 h by both of SJL formulas compared to morning types (p < 0.001). Participants in the highest SJL group (≥ 2 h) tended to have lower adherence to Baltic Sea Diet, however this association was statistically significant only among morning types (p = 0.006) as SJL was calculated by the sleep corrected formula. Participants in the lowest SJL-group consumed more berries, fruits and cereals and less alcohol compared to the participants in the highest SJL-group, but those were significant findings only among morning types (< 0.05). Participants in the highest SJL group were more obese measured by BMI and WC compared to the lowest SJL group (< 1 h) only among morning types (BMI, p = 0.016; WC, p = 0.012) by the sleep corrected SJL formula. Among evening types, there were not differences between SJL groups considering the obesity measurements. Results were similar about nutrition and obesity when SJL was calculated by the original SJL formula. Conclusion: Evening types suffer more of SJL, but it does not seem to be relevant for the quality of the diet or obesity as it is among morning types of which SJL is associated to the quality of the diet and prevalence of obesity. However, sleep debt does not seem to explain these findings.