Why do evening people consider themselves more intelligent than morning individuals? The role of big five, narcissism, and objective cognitive ability

Morningness and Conscientiousness: A Meta-analysis, Online Survey and Resting fMRI Study

Morningness is associated with several positive health outcomes and personality traits such as conscientiousness. In the current report, meta-analysis demonstrated a significant association between morningness and conscientiousness, data that are consistent with previous meta-analyses. Further, survey report and resting-state functional Magnetic Resonance Imaging (rs-fMRI, N = 43) indicated that the relationship between morningness and conscientiousness was moderated by functional connectivity with the Default Mode Network (DMN). DMN connectivity has been implicated in a number of cognitive functions and higher connectivity in this network is associated with higher conscientiousness.

The Relationship Between Big Five Personality Traits and Sleep Patterns: A Systematic Review

Sleep, an intrinsic aspect of human life, is experienced by individuals differently which may be influenced by personality traits and characteristics. Exploring how these traits influence behaviors and sleep routines could be used to inform more personalized and effective interventions to promote better sleep. Our objective was to summarize the existing literature on the relationship between personality traits and sleep patterns through a systematic review. An abstract and keyword search was conducted in PsycINFO, Cochrane and PubMed, collecting relevant literature, published between January 1980 and June 2024. A total of 1713 records were found, of which 18 studies were analyzed in the descriptive synthesis. Relevant studies covered populations in 11 different countries, Australia, China, Estonia, Finland, Germany, Italy, Japan, Poland, Turkey, the United Kingdom, and the United States, comprising a total of 58,812 subjects. All studies reported an association between a sleep pattern with at least one of the Big Five personality traits (agreeableness, conscientiousness, extraversion, neuroticism, openness to experience). Ten studies found associations between personality and sleep quality, all of which reported a link between neuroticism and sleep quality (effect sizes 0.183-0.40). Five studies found an association between conscientiousness and morningness (effect sizes 0.16-0.35). Other sleep patterns linked to personality traits included sleep duration, nightmare frequency and distress, sleep deficiency, sleep continuity, insomnia severity and sleep problems, sleep hygiene, sleep latency and daytime sleepiness. This novel systematic review confirms that sleep and personality traits are related, suggesting that those traits should be considered when trying to understand or change one's sleep behavior.

Greater social jetlag predicts poorer NIH Toolbox crystallized cognitive and academic performance in the Adolescent Brain Cognitive Development (ABCD) study

Academic performance plays a crucial role in long-term educational attainment and occupational function. Chronotype refers to an individual's daily tendencies for times for waking, activity, and sleep. Social jetlag reflects the mismatch between an individual's chronotype and their social schedule. Because school typically starts early in the morning, later chronotype is often associated with daytime sleepiness, insufficient sleep, and poor academic performance. However, the relationship between academic performance, chronotype, and social jetlag has not been extensively examined in large samples like the Adolescent Brain Cognitive Development (ABCD) study. We hypothesized that greater social jetlag would predict poorer cognitive and academic performance. Year 2 (ages 11-14) cross-sectional data from the ABCD cohort (n = 6,890 adolescents) were used to evaluate academic performance (i.e. self-reported past year grades), NIH Toolbox cognitive performance measures, chronotype, and social jetlag from the Munich Chronotype Questionnaire. We found that later chronotype and greater social jetlag predicted poorer cognitive and academic performance with small effect sizes. Our findings emphasize the importance of individual differences in chronotype and social jetlag when designing class schedules, as aligning school activities with student optimal sleep-wake times may contribute to improved academic performance.

Associations between chronotype and physical activity and well-being in adults

Circadian rhythms influence a preference for people's time of activity and sleep time during the day and the hours of best performance. The aim of the study was to assess the associations between chronotype, physical activity, and well-being in adults aged 20-50. The chronotype, physical activity and well-being scores were determined based on the Composite Scale of Morningness (CSM) questionnaire, the International Physical Activity Questionnaire (IPAQ) and the Well-Being Index (WHO-5) questionnaire, respectively. Study data consisted of the answers of 213 respondents (including 64 men) who took part in an online survey. The Spearman rank correlation coefficient and the matrix scatter plots were used to check the correlations between the CSM score and quality of life parameters' values. General linear models (GLMs) were performed to find differences in quality-of-life parameters between different combinations of sex and chronotype. Morning types showed the highest value of well-being score (mean = 13.48) while evening types the lowest one (mean = 8.35). Evening types spent the most time sitting compared to other chronotypes. Results of this study revealed the significant effect of chronotype on well-being and physical activity among adults. These findings suggest that chronotype is an important factor that psychologists and personal trainers should take into account.

Relation of resting brain signal variability to cognitive and socioemotional measures in an adult lifespan sample

Temporal variability of the fMRI-derived blood-oxygen-level-dependent (BOLD) signal during cognitive tasks shows important associations with individual differences in age and performance. Less is known about relations between spontaneous BOLD variability measured at rest and relatively stable cognitive measures, such as IQ or socioemotional function. Here, we examined associations among resting BOLD variability, cognitive/socioemotional scores from the NIH Toolbox and optimal time of day for alertness (chronotype) in a sample of 157 adults from 20 to 86 years of age. To investigate individual differences in these associations independently of age, we regressed age out from both behavioral and BOLD variability scores. We hypothesized that greater BOLD variability would be related to higher fluid cognition scores, more positive scores on socioemotional scales and a morningness chronotype. Consistent with this idea, we found positive correlations between resting BOLD variability, positive socioemotional scores (e.g. self-efficacy) and morning chronotype, as well as negative correlations between variability and negative emotional scores (e.g. loneliness). Unexpectedly, we found negative correlations between BOLD variability and fluid cognition. These results suggest that greater resting brain signal variability facilitates optimal socioemotional function and characterizes those with morning-type circadian rhythms, but individuals with greater fluid cognition may be more likely to show less temporal variability in spontaneous measures of BOLD activity.

Chronotype, Time of Day, and Performance on Intelligence Tests in the School Setting

Research suggests the existence of an association between chronotype and intellectual performance, but the nature of this link remains unclear. Studies conducted in a laboratory setting point to the synchrony effect (better performance at a person's preferred time of day) for fluid intelligence, but not for crystallized intelligence, whereas studies that have analyzed students' grades suggest that the effect exists for both. In the present study, we aimed to verify the synchrony effect by applying direct measures of crystallized intelligence, fluid intelligence, and subjective sleepiness-alertness in a sample of high school students during their morning or afternoon class. The results revealed a synchrony effect for crystallized, but not for fluid intelligence. During morning class, students with a morning chronotype performed better than evening chronotypes on a test of crystallized intelligence, whereas during afternoon class there was no difference between chronotypes. The association resulted from decreased performance during morning class in evening chronotypes that improved during afternoon class and constant performance in morning chronotypes. These effects were independent of sleepiness-alertness levels. The results suggest that individual differences between chronotypes may be important for tasks performed during morning classes, but not during afternoon ones, and that performance across school days may depend on time of day in evening chronotypes.

Circadian preference and intelligence - an updated meta-analysis

A large number of previous studies reported a link between circadian preference and psychometric intelligence with mixed results and various hypotheses about the source of this correlation. In this study, we aimed to update a previous meta-analysis about the correlation between circadian preference and intelligence. Our literature search identified a large number of new studies, resulting in an increase of over 100% in the number of studies and over 400% in the number of involved participants (total k = 30, total N = 11160) over the previous meta-analysis, sampling a much wider age range from children to adults in late middle age. Our meta-analysis revealed no significant link between morningness and intelligence (r = -0.008) when the entire sample was studied, and no evidence for publication bias. This overall effect, however, obscured the moderating effect of age. The morningness-intelligence correlation decreased with mean sample age (R² = 54%), ranging from a non-significant positive trend in children and adolescents to a significant negative correlation after young adulthood. Eveningness was positively correlated with intelligence (r = 0.056), but this finding is based on a more age-restricted sample and only reached significance with some model specifications. We hypothesize that the age-moderated correlation between circadian preference and intelligence reflects social effects, where more intelligent individuals are more able to adjust their daily schedules to their natural circadian rhythm.

Moral foundations in chronotypes: morningness predicts conservative morality

Recent studies suggest that chronopsychological variables may play an important role in moral behavior. In the present study, we aimed to test whether a person's chronotype is associated with moral foundations profiles, distinguished in accordance with Haidt's conceptualization. Morning-oriented people generally tended to rank the importance of the five basic moral foundations - Harm/Care, Fairness/Reciprocity, Ingroup/Loyalty, Authority/Respect, and Purity/Sanctity, highest. Moreover, morningness predicted the affiliation to the "conservative" cluster, as opposed to the "liberal" moral foundations profile. However, after conscientiousness was added to the model, the effect of chronotype was no longer significant. Thus, it seems that the more conservative morality of morning people stems mainly from their elevated conscientiousness. In addition to broadening the current knowledge about the morningness-eveningness' nomological network, the present results may have some practical implications, e.g., for political marketing strategies.

Biological Rhythm and Chronotype: New Perspectives in Health

The circadian rhythm plays a fundamental role in regulating biological functions, including sleep–wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person’s preferred time to be more active or to sleep can be expressed in the concept of morningness–eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest–activity circadian rhythm and sleep–wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

The search for causality of personality-chronotype associations: insights from a one-year longitudinal study of adolescents

Associations between certain personality traits and individual differences in diurnal preferences, referred to as morningness-eveningness, are well established from cross-sectional studies. However, it is unclear whether personality affects diurnal preference, diurnal preference affects personality, or some third factor influences both. The current study assessed the Big Five personality traits and morningness-eveningness in a one-year, two-wave longitudinal design, in a sample of 169 Polish high school students (59% females), aged 16-17 years (M = 16.80, SD = 0.39) during the first wave of measurement. During the second wave the participants were respectively 1 year older. Cross lagged panel analyses were run to determine wave 1 predictors of wave 2 variables. Cross-sectional analyses replicated the association between morningness and conscientiousness that has been reliably found in previous studies, but the cross-lagged paths between these variables were nonsignificant. These two traits appear to be intrinsically linked to one another by adolescence, possibly as a consequence of genetic influences that shape temperament earlier in childhood. In contrast, emotional stability and morningness were not significantly correlated in wave 1 cross-sectional data, but a significant relationship was found in the cross-lagged panel analysis. Wave 1 emotional stability predicted wave 2 morningness, although wave 1 morningness did not predict personality. We tentatively suggest that there may be a causal effect of personality on diurnal preference, associated with avoidance strategies for coping with academic stress as the high school years approach their end. More neurotic individuals may cope with their aversion to classes by distracting themselves with evening pursuits, such as use of the internet. Further work might examine in more depth how contextual stressors interact with personality to affect daily activities at different times of the day.