Circadian preferences and personality traits: A meta‐analysis

For Whom (and When) the Time Bell Tolls: Chronotypes and the Synchrony Effect

Circadian rhythms are powerful timekeepers that drive physiological and intellectual functioning throughout the day. These rhythms vary across individuals, with morning chronotypes rising and peaking early in the day and evening chronotypes showing a later rise in arousal, with peaks in the afternoon or evening. Chronotype also varies with age from childhood to adolescence to old age. As a result of these differences, the time of day at which people are best at attending, learning, solving analytical problems, making complex decisions, and even behaving ethically varies. Across studies of attention and memory and a range of allied areas, including academic achievement, judgment and decision-making, and neuropsychological assessment, optimal outcomes are found when performance times align with peaks in circadian arousal, a finding known as the synchrony effect. The benefits of performing in synchrony with one's chronotype (and the costs of not doing so) are most robust for individuals with strong morning or evening chronotypes and for tasks that require effortful, analytical processing or the suppression of distracting information. Failure to take the synchrony effect into consideration may be a factor in issues ranging from replication difficulties to school timing to assessing intellectual disabilities and apparent cognitive decline in aging.

Chronotype and sensory-processing sensitivity: A cross-sectional survey

Here we examined the possibility of a relationship of sensory processing sensitivity (SPS) with chronotype in a German-speaking sample of N = 1807 (1008 female, 799 male) with a mean age of 47.75 ± 14.41 y (range: 18-97 y). The data were collected using an anonymous online questionnaire (Chronotype: one item of the Morning-Evening-Questionnaire, as well as typical bedtimes on weekdays and weekends; SPS: German version of the three-factor model ; Big Five: NEO-FFI-30) between 21 and 27 April 2021. Results. We found morningness to correlate with the SPS facet low sensory threshold (LST), while eveningness correlated to aesthetic sensitivity (AES) and marginally significant to ease of excitation (EOE). Discussion: The results show that the correlations between chronotype and the Big Five personality traits are not consistent with the direction of the correlations between chronotype and the SPS facets. The reason for this could be different genes that are responsible for the individual traits influence each other differently depending on their expression.

Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation

Delayed sleep-wake phase disorder (DSWPD) is a sleep disorder in which the habitual sleep-wake timing is delayed, resulting in difficulty in falling asleep and waking up at the desired time. Patients with DSWPD frequently experience fatigue, impaired concentration, sleep deprivation during weekdays, and problems of absenteeism, which may be further complicated by depressive symptoms. DSWPD is typically prevalent during adolescence and young adulthood. Although there are no studies comparing internationally, the prevalence of DSWPD is estimated to be approximately 3% with little racial differences between Caucasians and Asians. The presence of this disorder is associated with various physiological, genetic and psychological as well as behavioral factors. Furthermore, social factors are also involved in the mechanism of DSWPD. Recently, delayed sleep phase and prolonged sleep duration in the young generation have been reported during the period of COVID-19 pandemic-related behavioral restrictions. This phenomenon raises a concern about the risk of a mismatch between their sleep-wake phase and social life that may lead to the development of DSWPD after the removal of these restrictions. Although the typical feature of DSWPD is a delay in circadian rhythms, individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the mechanism of this disorder. Recent studies have shown that DSWPD is frequently comorbid with psychiatric disorders, particularly mood and neurodevelopmental disorders, both of which have a bidirectional association with the pathophysiology of DSWPD. Additionally, patients with DSWPD have a strong tendency toward neuroticism and anxiety, which may result in the aggravation of insomnia symptoms. Therefore, future studies should address the effectiveness of cognitive-behavioral approaches in addition to chronobiological approaches in the treatment of DSWPD.

Relationship between chronotypes and aggression in adolescents: a cross-sectional study

BACKGROUND

This study aimed to investigate the relationship between chronotypes and aggression in adolescents.

METHODS

A cross-sectional study was conducted on 755 primary and secondary school students aged 11-16 years in rural areas of Ningxia Province, China. The Chinese version of the Buss-Perry Aggression Questionnaire (AQ-CV) and the Chinese version Morningness-Eveningness Questionnaire (MEQ-CV) were used to assess the aggressive behavior and chronotypes of the study subjects. The Kruskal-Wallis test was then used to compare the differences in aggression among adolescents with different chronotypes, and Spearman correlation analysis to determine the relationship between chronotypes and aggression. Further linear regression analysis was used to investigate the effects of chronotype, personality traits, family environment, and class environment on adolescent aggression.

RESULTS

There were significant differences in chronotypes between different age groups and different sexes. Spearman correlation analysis showed that the MEQ-CV total score was negatively correlated with the AQ-CV total score (r = -0.263) and score of each AQ-CV subscale. In Model 1, chronotypes were negatively associated with aggression when controlling for age and sex, and evening-type adolescents might be more likely to exhibit aggressive behavior (b = -0.513, 95% CI: [-0.712, -0.315], P < 0.001); in Model 2, the negative association remained after controlling for family and class environment on the basis of Model 1 (b = -0.404, 95% CI: [-0.601, -0.208], P < 0.001); and in Model 3, the negative association still existed after controlling for personality traits on the basis of Model 2 (b = -0.383, 95% CI: [-0.577, -0.190], P < 0.001).

CONCLUSION

Compared to morning-type adolescents, evening-type adolescents were more likely to exhibit aggressive behavior. Given social expectations for MT adolescents, adolescents should be actively guided to develop a good circadian rhythm that may be more conducive to their physical and mental development.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Morningness-Eveningness and Problematic Online Activities

Online activities and problematic online behaviors have recently emerged as important research topics. However, only a few studies have explored the possible associations between these behaviors and morningness-eveningness. The authors examined whether eveningness predicts these distinct problematic online behaviors differently and directly or via mediators. The associations between eveningness and three different problematic online behaviors (problematic Internet use, problematic online gaming, and problematic social media use) were explored among a large sample of Hungarian young adults (N = 1729, 57.2% female, Mage = 22.01, SDage = 1.97) by using a self-report survey. Depression and the time spent engaging in online activities were assessed as possible mediators. The effects of age and sex were controlled for. Using structural equation modeling, the results supported the association between eveningness and the higher risk for all three problematic online behaviors and highlighted that these associations were mediated by depressive mood and time spent on the activities. In addition, eveningness also predicted PIU directly. Eveningness is a risk factor for problematic online behaviors not only because of the higher amount of time spent on the activities but also because of the worse mood associated with eveningness. The results highlight that it is important to examine the different types of online activity separately and explore the role of diverse risk factors, among them morningness-eveningness.

Evening chronotype predicts dropout of physical exercise: a prospective analysis

Purpose

Eveningness preference to sleep/wake and perform physical/cognitive activities has been associated with worse health outcomes, when compared to morningness preference. Physical activity is one potential mediator that could explain this relationship; however, most of these evidences come from cross-sectional design studies. Our goal was to assess whether chronotype could predict the risk of dropout of physical exercise programs.

Methods

We followed 153 newly enrolled volunteers at three different gyms, from both sexes, aged between 18 and 65 years, during 12 weeks. The daily frequency of exercises in the programs was objectively measured (gym's electronic turnstiles). Using questionnaires, we collected data of variables related to demographic characteristics, health, physical activity, sleep, anthropometric and chronobiological parameters (Morningness-Eveningness Questionnaire-MEQ). Two multivariate models were created using Cox regression analysis to test the risk of dropout of physical exercise practice. Both models accounted for age, educational level, civil status, membership plan duration, physical exercise practice frequency during week 1 and chronotype (MEQ score and chronotypes).

Results

Model 1 results showed that higher MEQ score was associated with a lower chance of quitting the program (HR = 0.98; CI95% 0.95-1.00; p = 0.046). Considering the chronotypes, E-types showed the highest dropout risk compared to that of M-types (HR = 2.22; CI95% 1.09-4.52; p = 0.027).

Conclusion

Our results suggest that chronotype is another variable to be considered in future studies on promoting PAs in formal environments. Likewise, the practice frequency during week 1 and duration of membership plan also deserve more attention in additional studies.

Morning affect, eveningness, and amplitude distinctness: Associations with behavioural indicators of conscientiousness

Morningness is associated with well-being, better sleep quality, and more conscientiousness, while eveningness is associated with negative emotionality, poorer sleep quality, and less conscientiousness. The current study aimed to further understanding of associations with conscientiousness by assessing specific behavioural indicators of conscientiousness, morningness-eveningness, and also the Morning Affect and Distinctness (amplitude of diurnal variation) aspects of circadian functioning. A survey of Chinese university students (N = 369, aged 18-30, mean = 19.48, SD = 1.922; 108 males, 261 females), included the Morningness-Eveningness-Stability-Scale, measures of conscientiousness, mindfulness, life satisfaction, aspects of sleep, and the Behavioural Indicators of Conscientiousness (BIC) scale. Morningness and Morning Affect were positively correlated with life satisfaction, mindfulness, better sleep quality, more conscientiousness, and with BIC including Hardworking, Self-control, and Punctuality. Distinctness showed negative correlations with these variables. Negative correlations between Eveningness and conscientiousness, and the BIC subscales of Hardworking and Cleanliness were no longer significant after controlling for Morning Affect. Mediation analysis showed that the associations between Eveningness and conscientiousness/BIC were mediated by Morning Affect. These results extend previous research by showing associations between circadian functioning and specific behavioural indicators of conscientiousness, and suggest that low Morning Affect may provide a mechanism for the relationship between Eveningness and conscientiousness.

Normal lark, deviant owl: The relationship between chronotype and compliance with COVID-19 mitigation measures

Current evidence suggests that preventive measures, such as social distancing and wearing face masks, are critical to contain the spread of COVID-19. The recent burgeoning literature has empirically examined how a wide range of facet-level personality and individual-differences variables are associated with people's adherence to COVID-19 regulations. However, there lacks direct evidence regarding the role of chronotype in compliance with pandemic safety measures. According to the eveningness epidemiological liability hypothesis, people of later chronotype are more likely to breach COVID-19 restrictions. Despite this hypothesis shedding considerable light on the potential role of chronotype in the abidance of the virus-mitigating measures, it has not been rigorously tested using empirical data. To fill this gap, the present research investigated the link between morningness-eveningness and compliance with COVID-19 containment policies in Chinese samples. Two studies using multiple populations (students and community adults) and diverse measures of adherence to public health guidelines (self-report and actual behavior) consistently show that individuals who orient towards morningness display a higher level of compliance with COVID-19 prevention than people who orient towards eveningness. Overall, these findings present the first empirical confirmation of the eveningness epidemiological liability hypothesis, highlighting the role of chronotype in adherence to COVID-19 prevention guidelines.

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 psychometric properties of the Spanish version of the Morningness-Eveningness Stability Scale improved (MESSi) in adolescents

The aim of the present study was to adapt the Morningness-Eveningness-Stability Scale improved (MESSi) to the Spanish adolescent population, testing its factor structure and construct validity. The participants were 725 adolescents (52.9% girls; M = 14.8, SD = 1.99) who completed the MESSi, the Morningness Eveningness Scale of Children (MESC), questions about sleep habits adapted from the School Sleep Habits Survey, and self-reported academic performance. The psychometric results support a three-factor model with the factors of morning affect, eveningness, and distinctness, which show good internal consistency. The pattern of correlations between MESSi and the other measures was in the expected direction. The MESC correlated positively with morning affect and negatively with eveningness, whereas distinctness was uncorrelated. Boys reported higher morningness, whereas girls reported higher distinctness. Eveningness was negatively related to academic performance. Overall, the results support the validity and reliability of the Spanish adolescent version of the MESSi.

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.

The role of circadian typology in the relationship between perfectionism and workaholism

Workaholism is a work-related addiction, and the study of its antecedents has a strong individual and social impact. Several studies reported high trait perfectionism in individuals exhibiting workaholism. Although the relationship between perfectionism and workaholism is quite consistent in the literature, it is not yet clear which biological underlying mechanisms might explain this relationship. From a chronopsychological perspective, it has been widely demonstrated that evening-type individuals are more prone to develop addictive behaviour. In the present study, we investigated, for the first time, the role of circadian typology in the relationship between perfectionistic concerns and workaholism. A group of Italian workers (N = 369; 60.70% females; mean age of 38.60 years) took part in a survey. Participants filled in the Bergen Work Addiction Scale (for workaholism), the Morningness-Eveningness Questionnaire (for circadian typology), and the Short Almost-Perfect Scale (for perfectionism). In addition to age, we controlled for workload using the Job Content Questionnaire. Beyond the confirmation of the relationship between perfectionism and workaholism, we found that in high perfectionistic individuals, evening-types reported higher score in Bergen Work Addiction Scale. Based on these findings, limitations and suggestions for future research are discussed.

The moderating role of personality traits in the associations between seasonal fluctuations in chronotype and depressive symptoms

Recent research provided evidence that the well-established association between morningness-eveningness and depressive symptoms may be moderated by personality features - conscientiousness and neuroticism. In the present study, we attempted to broaden these findings using a longitudinal design. We hypothesized that these personality traits may influence the degree to which morningness-eveningness and depressiveness covary in time. Participants (n = 380) filled measures of morningness-eveningness, the Big Five personality, and depressive symptoms twice, in December and in June. Consistent with previous results, we observed a significant seasonal shift towards morningness and lower depressive symptoms from December to June. Seasonal shifts in chronotype and depressive symptoms were interrelated: a seasonal shift towards morningness was associated with a decrease in depressive symptoms. The strength of this association was exaggerated by neuroticism but attenuated by conscientiousness, suggesting that among neurotic individuals seasonal changes in depressive symptomatology are more dependent on seasonal shifts in morningness-eveningness but less dependent among conscientious ones. This result suggests that conscientiousness and emotional stability play a protective role against maladaptive consequences of eveningness.

Identifying Insomnia From Social Media Posts: Psycholinguistic Analyses of User Tweets

Background

Many people suffer from insomnia, a sleep disorder characterized by difficulty falling and staying asleep during the night. As social media have become a ubiquitous platform to share users’ thoughts, opinions, activities, and preferences with their friends and acquaintances, the shared content across these platforms can be used to diagnose different health problems, including insomnia. Only a few recent studies have examined the prediction of insomnia from Twitter data, and we found research gaps in predicting insomnia from word usage patterns and correlations between users’ insomnia and their Big 5 personality traits as derived from social media interactions.

Objective

The purpose of this study is to build an insomnia prediction model from users’ psycholinguistic patterns, including the elements of word usage, semantics, and their Big 5 personality traits as derived from tweets.

Methods

In this paper, we exploited both psycholinguistic and personality traits derived from tweets to identify insomnia patients. First, we built psycholinguistic profiles of the users from their word choices and the semantic relationships between the words of their tweets. We then determined the relationship between a users’ personality traits and insomnia. Finally, we built a double-weighted ensemble classification model to predict insomnia from both psycholinguistic and personality traits as derived from user tweets.

Results

Our classification model showed strong prediction potential (78.8%) to predict insomnia from tweets. As insomniacs are generally ill-tempered and feel more stress and mental exhaustion, we observed significant correlations of certain word usage patterns among them. They tend to use negative words (eg, “no,” “not,” “never”). Some people frequently use swear words (eg, “damn,” “piss,” “fuck”) with strong temperament. They also use anxious (eg, “worried,” “fearful,” “nervous”) and sad (eg, “crying,” “grief,” “sad”) words in their tweets. We also found that the users with high neuroticism and conscientiousness scores for the Big 5 personality traits likely have strong correlations with insomnia. Additionally, we observed that users with high conscientiousness scores have strong correlations with insomnia patterns, while negative correlation between extraversion and insomnia was also found.

Conclusions

Our model can help predict insomnia from users’ social media interactions. Thus, incorporating our model into a software system can help family members detect insomnia problems in individuals before they become worse. The software system can also help doctors to diagnose possible insomnia in patients.

Dissecting the midlife crisis: disentangling social, personality and demographic determinants in social brain anatomy

In any stage of life, humans crave connection with other people. In midlife, transitions in social networks can relate to new leadership roles at work or becoming a caregiver for aging parents. Previous neuroimaging studies have pinpointed the medial prefrontal cortex (mPFC) to undergo structural remodelling during midlife. Social behavior, personality predisposition, and demographic profile all have intimate links to the mPFC according in largely disconnected literatures. Here, we explicitly estimated their unique associations with brain structure using a fully Bayesian framework. We weighed against each other a rich collection of 40 UK Biobank traits with their interindividual variation in social brain morphology in ~10,000 middle-aged participants. Household size and daily routines showed several of the largest effects in explaining variation in social brain regions. We also revealed male-biased effects in the dorsal mPFC and amygdala for job income, and a female-biased effect in the ventral mPFC for health satisfaction.

Hannah Kiesow et al. combine 40 behavioral indicators and neuroimaging data from the UK Biobank to investigate how the transitions in midlife in the domains of social, personality, and demographic determinants impact brain anatomy. Through Bayesian analyses, the authors were able to disentangle which specific traits, relative to other considered candidate traits, contributed the most to explaining differences in social brain volume.

Demographic, psychological, chronobiological, and work-related predictors of sleep disturbances during the COVID-19 lockdown in Italy

The first COVID-19 contagion wave caused unprecedented restraining measures worldwide. In Italy, a period of generalized lockdown involving home confinement of the entire population was imposed for almost two months (9 March-3 May 2020). The present is the most extensive investigation aimed to unravel the demographic, psychological, chronobiological, and work-related predictors of sleep disturbances throughout the pandemic emergency. A total of 13,989 Italians completed a web-based survey during the confinement period (25 March-3 May). We collected demographic and lockdown-related work changes information, and we evaluated sleep quality, insomnia and depression symptoms, chronotype, perceived stress, and anxiety using validated questionnaires. The majority of the respondents reported a negative impact of confinement on their sleep and a delayed sleep phase. We highlighted an alarming prevalence of sleep disturbances during the lockdown. Main predictors of sleep disturbances identified by regression models were: female gender, advanced age, being a healthcare worker, living in southern Italy, confinement duration, and a higher level of depression, stress, and anxiety. The evening chronotype emerged as a vulnerability factor, while morning-type individuals showed a lower predisposition to sleep and psychological problems. Finally, working from home was associated with less severe sleep disturbances. Besides confirming the role of specific demographic and psychological factors in developing sleep disorders during the COVID-19 pandemic, we propose that circadian typologies could react differently to a particular period of reduced social jetlag. Moreover, our results suggest that working from home could play a protective role against the development of sleep disturbances during the current pandemic emergency.

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

INTRODUCTION

Diurnal preferences have been linked to personality but often with mixed results. The present study examines the relationships between sleep timing (chronotype), diurnal preferences, and the Five-Factor Model of personality traits at the phenotypic and genetic level.

METHODS

Self- and informant-reports of the NEO Personality Inventory-3, self-reports of the Munich Chronotype Questionnaire, and DNA samples were available for 2,515 Estonian adults (M_age  = 45.76 years; 59% females). Genetic correlations were obtained through summary statistics of genome-wide association studies.

RESULTS

Results showed that higher Conscientiousness and lower Openness to Experience were significant predictors of earlier chronotype. At the level of facets, we found that more straightforward (A2) and excitement-seeking (E5), yet less self-disciplined (C5) people were more likely to have later chronotypes. The nuance-level Polypersonality score was correlated with chronotype at r = .28 (p < .001). Conscientiousness and Openness were genetically related with diurnal preferences. The polygenic score for morningness-eveningness significantly predicted the Polypersonality score.

CONCLUSION

Phenotypic measures of chronotype and personality showed significant associations at all three of levels of the personality hierarchy. Our findings indicate that the relationship between personality and morningness-eveningness is partly due to genetic factors. Future studies are necessary to further refine the relationship.

The Emerging Circadian Phenotype of Borderline Personality Disorder: Mechanisms, Opportunities and Future Directions

PURPOSE OF REVIEW

We review the recent evidence suggesting that circadian rhythm disturbance is a common unaddressed feature of borderline personality disorder (BPD); amelioration of which may confer substantial clinical benefit. We assess chronobiological BPD studies from a mechanistic and translational perspective and highlight opportunities for the future development of this hypothesis.

RECENT FINDINGS

The emerging circadian phenotype of BPD is characterised by a preponderance of comorbid circadian rhythm sleep-wake disorders, phase delayed and misaligned rest-activity patterns and attenuated amplitudes of usually well-characterised circadian rhythms. Such disturbances may exacerbate symptom severity, and specific maladaptive personality dimensions may produce a liability towards extremes in chronotype. Pilot studies suggest intervention may be beneficial, but development is limited. Endogenous and exogenous circadian rhythm disturbances appear to be common in BPD. The interface between psychiatry and chronobiology has led previously to novel efficacious strategies for the treatment of psychiatric disorders. We believe that better characterisation of the circadian phenotype in BPD will lead to a directed biological target for treatment in a condition where there is a regrettable paucity of accessible therapies.

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.

Relationship Between Big Five Personality Dimensions, Chronotype, and DSM-V Personality Disorders

Morningness-eveningness (M/E) is an important variable in individual differences and has an impact on many areas of life including general and mental health. In previous work eveningness has shown to correlate to personality disorders (PDs) and mental instability such as psychoticism, depression, and bipolar disorders. Therefore, a relationship between M/E and PDs can be assumed but has never been tested. The aim of this study was to assess a possible relationship between DSM-5-PDs and circadian timing (chronotype; M/E). We used the Morningness-Eveningness Stability Scale improved and clock time-based measurements, the PID-5 brief version, and the Big Five brief version. Sample: N = 630; mean age: 27.76 years, SD: 11.36 years; 137 male, 489 female, 4 diverse. In this short screening a relationship between eveningness and DSM-5-personality traits, (evening-oriented participants showing a higher PID-5 score: morningness -0.208/p < 0.001; eveningness: 0.153/p < 0.001) was found. Moreover, participants with high levels of distinctness (fluctuations of the perceived energy level during the day) are prone to PDs too, with distinctness being the best predictor for a high PID-5 score in this sample (0.299/p < 0.001). In the regression analysis, neuroticism, agreeableness, conscientiousness, and extraversion contributed significantly to the model with higher scores on extraversion, agreeableness and conscientiousness being related to lower scores on the PID-5. Neuroticism was positively related to PID-5 scores. Later midpoint of sleep (higher eveningness) was associated with higher PID-5 scores, as were higher fluctuations/amplitude during the day.

Circadian Typology and Personality Dimensions of Croatian Students of Health-Related University Majors

The aim of this study was to determine the relationship between circadian preferences and personality dimensions among 712 students of three different majors from the Faculty of Medicine, Osijek: medical students (MD), nursing students (RN) and medical laboratory diagnostics students (MLD). For the measurement of personality dimensions, the IPIP50 Big-Five questionnaire was used. The circadian preference of students was assessed using the reduced morningness-eveningness questionnaire (rMEQ). Several significant results were observed and there was a significant difference in circadian preference among the three tested groups, with RN students scoring highest on the morningness scale and MLD students scoring the lowest. RN students scored significantly higher on agreeableness and conscientiousness than the other two groups. On the other hand, MD students scored higher on intellect than the MLD students. MLD students scored the lowest on emotional stability scales. Morning type students had higher conscientiousness and emotional stability scores. These results imply that circadian preference and personality traits are crucial elements of medical professionals' wellbeing. With this paper, we would like to raise awareness about common personality traits and adherence to certain circadian orientations in medical professionals as a motivation to introduce a more flexible view towards strict time and task divisions in everyday practice.

Angry night birds: Emotionality, activity and sociability temperament in adolescent chronotypes

There is growing interest in personality profiles associated with morningness-eveningness to foster an understanding of the behaviors and mental states of chronotypes. This study aimed to analyze the domains of emotionality, activity and sociability (EAS) temperament in relation to morningness-eveningness in adolescents. A sample of 539 school pupils aged 13-19 years completed the EAS Temperament Survey, the Composite Scale of Morningness and the Munich Chronotype Questionnaire. Amongst the five EAS domains (emotionality-distress, emotionality-fearfulness, emotionality-anger, activity and sociability), greater emotionality-anger was related to eveningness, while greater emotionality-distress was related to lower social jet lag. The results suggest that evening chronotypes can be temperamentally inclined to anger. The possible mechanisms of this association are discussed.

Psychopathy and chronotype disposition: the mediating role of depression

This study examined the relationship between dark triad personality traits and chronotype disposition, whilst incorporating the mediating role of anxiety and/or depression after excluding individuals presenting insomnia and/or physiological sleep-disorder symptoms. Members of the general population (N = 453) completed online measures of dark triad personality traits, chronotype, and anxious and depressive symptoms. Psychopathy and Machiavellianism were independently related to an evening chronotype disposition. However, after accounting for age, sex, anxiety and depression, psychopathy and depression remained the only significant predictors of chronotype. Therefore, whilst psychopathy was the strongest predictor of an evening chronotype preference, this relationship is partially mediated by depression. Individuals presenting an evening disposition may display increased psychopathic traits due to greater emotion dysregulation. This is potentially perpetuated by depressive symptoms stemming from a delayed or blunted affective rhythm. Interacting factors (e.g. reduced light exposure) may also contribute to alterations in the biological rhythm amongst evening-types, resulting in a negative feedback cycle. Targeting chronotype and depressive symptoms amongst individuals presenting psychopathic tendencies could increase the efficacy of existing sleep-based interventions for hostile behaviour.

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

Morningness-eveningness, or chronotype, reflects the timing of sleep-wake patterns across a 24-hour day. Extant research has revealed that chronotype correlates with numerous psychological constructs including cognitive ability. In the current research, we examined how people with different chronotypes perceive their intelligence. We expected eveningness to be positively associated with subjectively assessed intelligence (SAI) because evening chronotypes demonstrate slightly higher intelligence than morning individuals. Furthermore, we considered personality traits (Big Five and narcissism) and objective intelligence (measured with standardized tests of fluid and verbal IQ) as potential variables that could account for this relationship. Across two studies (N = 504 and 232), we found that eveningness was associated with higher SAI. This relationship remained significant even after controlling for objective intelligence. In Study 1, we also found that when conscientiousness and neuroticism were analyzed together with chronotype, the magnitude of positive association between eveningness and SAI increased. Furthermore, Study 2 revealed that evening individuals exhibited higher narcissism, which fully accounted for their intelligence self-views. In the discussion, we speculate that daily struggles of evening chronotypes to function in morning-oriented society give them a basis to think positively about their intelligence to the extent of positive bias.

Validity and reliability of the Slovene version of the Morningness-Eveningness Questionnaire

Morningness-eveningness (ME) can be defined as individual differences in sleep-wake patterns, and the time of day people feel and perform best. Various self-report instruments that measure ME have been developed. The Horne and Östberg Morningness-Eveningness Questionnaire (MEQ) has most frequently been used for classifying ME types. The aim of this study was to investigate the validity and reliability of the Slovene version of the MEQ (Slovene MEQ). Two hundred and sixty-five participants (65.3% women, 34,7% men, mean age 38,1 years, range 19-67) took the Slovene MEQ twice, 2 weeks apart (MEQ test and retest). Internal consistency of the Slovene MEQ items was high, with Cronbach's Alpha coefficients of 0.86. The test-retest reliability was also high, with intraclass correlation coefficient (ICC) of 0.96. The classification of chronotypes on middle-aged population offered a more balanced representation of the five chronotypes than those proposed by the authors Horne and Östberg . Age changes in chronotype could be confirmed in this study in the supposed direction with older adults being more morning-oriented. The criterion validity of the Slovene MEQ through the relationship of morningness and basic personality traits showed that conscientiousness and agreeableness demonstrated positive and significant correlations with morningness. A low negative correlation was observed between openness and morningness, with higher eveningness among more open participants.

Mismatch between perceived family and individual chronotype and their association with sleep-wake patterns

While social zeitgebers are known to shape diurnal preference, little research has been devoted to determining the contribution of the familiar group chronotype as social zeitgeber on individual circadian rhythms and sleep-wake patterns in adult subjects. The current study aimed to examine the matching between perceived family chronotype and individual chronotype and their relationship with sleep-wake patterns on weekdays and weekends, diurnal subjective somnolence, and substance consumption. Nine hundred and forty-two Colombian adults completed the Composite Scale of Morningness, the Epworth Sleepiness Scale, and responded to a questionnaire about circadian preferences of their family nucleus. We found evidence of a mismatch between perceived family and individual chronotype, mainly for morning-type individuals (Cohen's Kappa = -0.231; p < 0.001). This mismatch was associated with diurnal subjective somnolence (β = 0.073; p < 0.001) and specific sleep-wake patterns (p < 0.01). In addition, subjects with evening-type families showed higher caffeine and alcohol consumption (p < 0.001). To our knowledge, this is the first study to assess and report the mismatching between perceived family and individual chronotypes, and it adds to the existing body of knowledge regarding the influence of social zeitgebers on circadian rhythms. This is particularly relevant since mismatching between circadian physiology and environmental cues have been shown to lead to diverse pathologies.

The impact of chronotype on prosocial behavior

INTRODUCTION

Chronotype (morningness/eveningness) is associated with preference for the timing of many types of behavior, most notably sleep. Chronotype is also associated with differences in the timing of various physiologic events as well as aspects of personality. One aspect linked to personality, prosocial behavior, has not been studied before in the context of chronotype. There are many variables contributing to who, when, and why one human might help another and some of these factors appear fixed, while some change over time or with the environment. It was our intent to examine prosocial behavior in the context of chronotype and environment.

METHODS

Randomly selected adults (N = 100, ages 18-72) were approached in a public space and asked to participate in a study. If the participants consented (n = 81), they completed the reduced Morning-Eveningness Questionnaire and the Stanford Sleepiness Scale, then prosocial behavior was assessed.

RESULTS/CONCLUSIONS

We found that people exhibited greater prosocial behavior when they were studied further from their preferred time of day. This did not appear to be associated with subjective sleepiness or other environmental variables, such as ambient illumination. This suggests the importance of appreciating the differentiation between the same individual's prosocial behavior at different times of day. Future studies should aim at replicating this result in larger samples and across other measures of prosocial behavior.

Is Santa Claus an evening owl?

Case studies have a long tradition in biomedical research. Here, I will analyze an important person from a chronobiological aspect, Santa Claus. Although it might be dangerous for researchers to publish analyses about Santa Claus, because, given the possibility that he may be unsatisfied with my analysis, this could lead to an embargo of parcels for my whole family. Nevertheless, some intrepid researches already diagnosed Santa Claus, ending up in some important research results. A search in Web of Science revealed only N = 224 publications about Santa Claus, which is really low. The question, I am addressing here is, whether Santa Claus is an "evening owl" or a night chronotype. In this report, I summarize the facts known about Santa Claus on the one side and about evening chronotypes on the other and sum up these results in a "vote counting" manner as pros and cons. The results are summarized in Table 1. In total, there is 12 times support for the hypothesis, 2 times against and 1 equivocal (Table 1). This result is significant (binomial test, p = 0.013). Therefore, the conclusion is "Santa Claus is an evening type".

How Young “Early Birds” Prefer Preservation, Appreciation and Utilization of Nature

Since the 1990s, the Two Major Environmental Value model (2-MEV) has been applied to measure adolescent environmental attitudes by covering two higher order factors: (i) Preservation of Nature (PRE) which measures protection preferences and (ii) Utilization of Nature (UTL) which quantifies preferences towards exploitation of nature. In addition to the 2-MEV scale, we monitored the Appreciation of Nature (APR) which, in contrast to the UTL, monitors the enjoyable utilization of nature. Finally, we employed the Morningness–Eveningness Scale for Children (MESC) which monitors the diurnal preferences and associates with personality and behavioral traits. In this study, we analyzed data from 429 Irish students (14.65 years; ±1.89 SD) with the aim of reconfirming the factor structure of the 2-MEV+APR and monitoring the relationship between the MESC and the environmental values (PRE, UTL, APR). Our findings identified a significant association between PRE and APR with MESC. In addition, we observed a gender difference. Our results suggest that morningness preference students are more likely to be protective of and appreciative towards nature. Recommendations for outreach programs as well as conclusions for environmental education initiatives in general are discussed.

Assessing the Dim Light Melatonin Onset in Adults with Autism Spectrum Disorder and No Comorbid Intellectual Disability

This study assessed melatonin levels and the dim light melatonin onset (DLMO) in adults with Autism Spectrum Disorder (ASD) and also investigated the relationships between melatonin and objectively measured sleep parameters. Sixteen adults with ASD (ASD-Only), 12 adults with ASD medicated for comorbid diagnoses of anxiety and/or depression (ASD-Med) and 32 controls participated in the study. Although, the timing of the DLMO did not differ between the two groups, advances and delays of the melatonin rhythm were observed in individual profiles. Overall mean melatonin levels were lower in the ASD-Med group compared to the two other groups. Lastly, greater increases in melatonin in the hour prior to sleep were associated with greater sleep efficiency in the ASD groups.

Examining the Behavioural Sleep-Wake Rhythm in Adults with Autism Spectrum Disorder and No Comorbid Intellectual Disability

This study aimed to examine the behavioural sleep-wake rhythm in 36 adults with autism spectrum disorder (ASD) and to determine the prevalence of circadian sleep-wake rhythm disorders compared to age- and sex-matched controls. Participants completed an online questionnaire battery, a 14-day sleep-wake diary and 14-day actigraphy assessment. The results indicated that a higher proportion of adults with ASD met criteria for a circadian rhythm sleep-wake disorder compared to control adults. In particular, delayed sleep-wake phase disorder was particularly common in adults with ASD. Overall the findings suggest that individuals with ASD have sleep patterns that may be associated with circadian rhythm disturbance; however factors such as employment status and co-morbid anxiety and depression appear to influence their sleep patterns.

The relationship between chronotype and depressive symptoms: A meta-analysis

BACKGROUND

Expanding our understanding of the factors that influence depression is crucial for prognosis and treatment. In light of increasing evidence of an association between disrupted circadian rhythms and affective symptoms, a meta-analysis was used to examine the relationship between an eveningness chronotype and depression.

METHODS

Electronic searches of the PsycINFO, Medline, Scopus, and Google Scholar databases were conducted in February 2016. Relevant reviews, related journals, and reference lists were manually searched. Statistical data were reported or transformed to a Fisher's z correlational coefficient for effect size analysis.

RESULTS

Data from 36 studies (n =15734) met the inclusion criteria and were analysed under a random effects model. Nearly all included studies utilised the Composite Scale of Morningness (CSM) or the Morningness-Eveningness Questionnaire (MEQ) as a measure of chronotype. Overall effect size from 58 effect sizes was small (z=-.20; 95% CI: -.18 to -.23). Effect sizes based on the CSM were significantly larger than those based on the MEQ. There was no evidence of publication bias.

LIMITATIONS

The number of studies comparing different mood disorders or the potential moderating effects of gender and age were too few to draw conclusions regarding their respective effect sizes. Future research should utilise longitudinal designs to draw causal inferences on the directionality of this relationship.

CONCLUSIONS

Findings from this meta-analysis indicate an eveningness orientation is somewhat associated with more severe mood symptoms. Chronobiological approaches may contribute to the prevention and treatment of depressive disorders.