Personality traits relate to chronotype at both the phenotypic and genetic level

Mediation analysis of circadian preferences and other behavioral and sociodemographic factors associated with subjective well-being in undergraduate students

Undergraduate students are usually subjected to a routine with constant pressure, stress, circadian misalignment, and sleep irregularity that impairs their subjective well-being. Recent evidence suggests that circadian preference is also a risk factor for impaired mental health and factors related to subjective well-being. This study aimed to identify the sociodemographic factors associated with subjective well-being and describe the mediating behavioral variables. Between September 2018 and March 2021, 615 Brazilian students enrolled in higher educational institutions completed an electronic form containing questionnaires on subjective well-being, sociodemographic, and behavioral-related factors (convenience sample). A statistical mediation model was applied to describe how these variables influence subjective well-being. We observed that Morningness (p < .001), identification with the male gender (p = .010), not working while studying (p = .048), and the practice of Pilates/yoga (p = .028) were associated with greater subjective well-being. Except for employment status, no direct effects were observed, which reinforces the need to consider a multidimensional approach. The relationship between subjective well-being and sociodemographic factors exists only in the presence of behavioral mediators, specifically perceived stress, daytime sleepiness, symptoms of depression, sleep quality, and positive and negative affects. Future work should investigate in more detail the impact of sleep, stress, and circadian preferences on this relationship.

The association of chronotype and social jet lag with body composition in German students: The role of physical activity behaviour and the impact of the pandemic lockdown

Young adults with a later chronotype are vulnerable for a discrepancy in sleep rhythm between work- and free days, called social jet lag (SJL). This study analysed (i) chronotype/SJL association with visceral fat/skeletal muscle mass, (ii) the attribution to physical activity behaviour, and (iii) chronotype-specific changes in physical activity behaviour in young adults during the Covid-19 pandemic lockdown. Chronotype and SJL were derived from the Munich-Chrono-Type-Questionnaire in 320 German students (age 18-25 years) from September 2019 to January 2020, 156 of these participated in an online follow-up survey in June 2020. Body composition was assessed by bioimpedance analysis at baseline. Multivariable linear regression analyses were used to relate chronotype/SJL to body composition; the contribution of self-reported physical activity was tested by mediation analysis. At baseline, a later chronotype and a larger SJL were associated with a higher visceral fat mass (P<0.05), this relation was notably mediated by the attention to physical activity (P<0.05). Chronotype (P = 0.02) but not SJL (P = 0.87) was inversely associated with skeletal muscle mass. During the pandemic lockdown, chronotype hardly changed, but SJL was reduced. Timing and physical activity behaviour remained in most participants and changes were unrelated to chronotype (all P>0.07). A later chronotype/higher SJL may increase the risk of a higher visceral fat mass even in this relatively healthy sample, which may be partly due to their physical activity behaviour. Despite a reduction in SJL during the pandemic lockdown, later chronotypes did not change their physical activity behaviour more than earlier chronotypes.

Diurnal Preference and Correlates of Multidimensional Perfectionism, Type-D Personality, and Big Five Personality Traits

This study examined the extent to which the dimensions of the five-factor model, Type-D personality, and multidimensional perfectionism were associated with a diurnal preference in the general population. A sample of (N = 864) individuals completed the measures of diurnal preference, multidimensional perfectionism, Type-D personality, and the Big Five traits. A correlational analysis determined that agreeableness, conscientiousness, emotional stability, organization, and personal standards were independently related to morningness. In contrast, negative affect, social inhibition, Type-D personality, and perfectionistic doubts and concerns, as well as an increased perception of critical parental evaluation, were independently related to eveningness. After accounting for the shared variance amongst the personality traits, only negative affect, conscientiousness, organization, personal standards, and parental perception were significantly associated with diurnal preference. The current outcomes offer further insight into the relationship between personality and diurnal preference. Here, we observed greater reports of adaptive personality traits in relation to morningness, whereas negative affect and perceived parental evaluation and criticism were related to eveningness. As the first study to examine the relationship between Type-D personality, multidimensional perfectionism, and diurnal preference, the current outcomes should be considered preliminary.

The Effect of Personality on Chrononutrition during the COVID-19 Lockdown in Qatar

The COVID-19 lockdown has had a significant impact on people’s lives worldwide. This study aimed to investigate the effect of personality on chrononutrition during the COVID-19 lockdown. Using a cross-sectional design, a convenient sample of 543 adults in Qatar completed an online questionnaire using validated tools to assess personality and chrononutrition behaviors during the first COVID-19 lockdown. Participants scoring high in openness were more likely to eat at night (mean difference (MD) = 0.41, 95% confidence interval (CI): 0.10, 0.72) compared to those scoring high in agreeableness, while those scoring high in extraversion and openness had a shorter eating window (MD = −76.6, 95%CI: −146.3, −6.93 and MD = −29.8, 95%CI: −56.5, −3.01, respectively). Participants high in extraversion had longer evening latency (MD = 66.3, 95%CI: 25.4, 107.3) and evening eating (MD = −62.0, 95%CI: −114.0, −9.0) compared those high in agreeableness. Participants high in conscientiousness showed evidence of first eating event misalignment during the weekend (MD = 22.0, 95%CI: 0.15, 43.9) and last eating event misalignment during weekdays (MD = −27.8, 95%CI: −47.3, −8.41) compared to those high in agreeableness. Lastly, participants high in openness showed evidence of eating window misalignment during the weekend (MD = 30.6, 95%CI: 5.01, 56.2). This study suggests that personality traits can inform personalized nutritional approaches when aiming for healthy habits during unexpected periods, such as the COVID-19 pandemic.

Morning preference is associated with subjective happiness among Japanese female workers: A moderation analysis by sleep characteristics from the SLEPT study

Research on mental health in working populations has predominantly focussed on negative outcomes, while studies on the positive aspects of life remain very limited, especially in Japan. Although morningness has recently been considered a factor for being happy, the role of sleep characteristics as it relates to the association between morningness and happiness has not been substantiated. The aim of this study is to investigate the associations between diurnal preference and level of subjective happiness in healthy, full-time, daytime workers in Japan. We also tested the moderation effect of sleep parameters on the relationship between diurnal preference and subjective happiness. This is an exploratory analysis from the cross-sectional data of the SLeep Epidemiology Project at the University of Tsukuba (SLEPT Study). Subjective happiness was evaluated using a single-item question. Diurnal preference was assessed using the Morningness-Eveningness Questionnaire (MEQ), in which higher scores indicate greater tendency to have morning preference. The participants underwent assessment of sleep parameters for 7 consecutive days using a waist-worn actigraphy device and kept a sleep diary. Sleep parameters investigated were subjective sleep quality, sleep disturbance, daytime sleepiness, weekend oversleep, total sleep time, sleep onset time, wake time, and sleep efficiency. A total of 205 males (average 42.6 ± 10.4 years) and 272 females (41.1 ± 9.8 years) were eligible for analysis. Hierarchical liner regression analysis was used to show the relationships of subjective happiness with MEQ score, and the sleep parameters. Further, moderation analysis was conducted by adding the interaction between MEQ score and the sleep parameters. After adjusting for age, psychological distress, self-rated health, and occupational stress, we found that subjective happiness was significantly associated with higher MEQ score and sleep efficiency but only in female. The moderating role of sleep parameters was not found. We discussed the implications of the obtained results and a possible strategy to maintain and improve subjective happiness of female workers who have evening preference.

Chrono-communication and cardiometabolic health: The intrinsic relationship and therapeutic nutritional promises

Circadian rhythm, an innate 24-h biological clock, regulates several mammalian physiological activities anticipating daily environmental variations and optimizing available energetic resources. The circadian machinery is a complex neuronal and endocrinological network primarily organized into a central clock, suprachiasmatic nucleus (SCN), and peripheral clocks. Several small molecules generate daily circadian fluctuations ensuring inter-organ communication and coordination between external stimuli, i.e., light, food, and exercise, and body metabolism. As an orchestra, this complex network can be out of tone. Circadian disruption is often associated with obesity development and, above all, with diabetes and cardiovascular disease onset. Moreover, accumulating data highlight a bidirectional relationship between circadian misalignment and cardiometabolic disease severity. Food intake abnormalities, especially timing and composition of meal, are crucial cause of circadian disruption, but evidence from preclinical and clinical studies has shown that food could represent a unique therapeutic approach to promote circadian resynchronization. In this review, we briefly summarize the structure of circadian system and discuss the role playing by different molecules [from leptin to ghrelin, incretins, fibroblast growth factor 21 (FGF-21), growth differentiation factor 15 (GDF15)] to guarantee circadian homeostasis. Based on the recent data, we discuss the innovative nutritional interventions aimed at circadian re-synchronization and, consequently, improvement of cardiometabolic health.