Relationship between circadian typology and big five personality domains

Sleep Quality, but Not Personality Traits, Mediates the Relationship between Chronotype and Life Satisfaction: A Study in Young Adults

Chronotype reflects the morningness-eveningness preference over a 24 h period. Significant data indicate meaningful differences between evening types (ETs) and morning types (MTs) in behavior, personality traits, health, and well-being. This study explores the interactions between chronotype, sleep, personality, and life satisfaction among 254 undergraduate college students (mean age 23.79 ± 1.85). Using online questionnaires, the participants provided demographic information and completed assessments, including the Morningness-Eveningness Questionnaire (MEQ), the Pittsburg Sleep Quality Index (PSQI), a shortened version of the Big Five Inventory (BFI-10), and a life satisfaction uniscale measure. The results revealed a significant association between chronotype and both life satisfaction and sleep quality, where ETs exhibited poorer outcomes compared to MTs. Additionally, the chronotype correlated with agreeableness and conscientiousness, with later chronotypes linked to reduced scores in these personality traits. A key finding in this study was revealed in a mediation analysis in which sleep quality was found to mediate the relationship between chronotype and life satisfaction. The mediation analysis highlighted sleep quality as a crucial process connecting chronotype to life satisfaction. The findings emphasize the importance of addressing sleep quality in interventions aimed at enhancing life satisfaction and overall well-being among ETs. Overall, our results provide valuable insights into the intricate relationships between chronotype, personality, sleep quality, and subjective well-being.

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.

Godless owls, devout larks: Religiosity and conscientiousness are associated with morning preference and (partly) explain its effects on life satisfaction

The associations between morningness-eveningness, conscientiousness, and religiosity have not been investigated to date. The aim of the present research was to provide evidence for the relationships between these dimensions. Moreover, we tested whether the well-established link between morningness and life satisfaction could be explained by elevated religiosity of morning-oriented individuals and whether this relationship may be mediated by conscientiousness. The investigation was conducted on two independent samples of Polish adults (N = 500 and N = 728). Our results corroborated earlier findings that morningness was positively associated with both conscientiousness and satisfaction with life. We also found evidence for a significant positive association between morningness and religiosity. Moreover, controlling for age and gender, we obtained significant mediation effects showing that the association between morningness-eveningness and satisfaction with life might stem, at least in part, from the higher religiosity among morning-oriented individuals, also when conscientiousness was included in the model. It means that more morning-oriented individuals may benefit from higher psychological well-being thanks to both personality characteristics and attitudes towards religion.

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.

Chronotype, Longitudinal Volumetric Brain Variations Throughout Adolescence, and Depressive Symptom Development

OBJECTIVE

Adolescence is a critical period for circadian rhythm, with a strong shift toward eveningness around age 14. Also, eveningness in adolescence has been found to predict later onset of depressive symptoms. However, no previous study has investigated structural variations associated with chronotype in early adolescence and how this adds to the development of depressive symptoms.

METHOD

Assessment of 128 community-based adolescents (51% girls) at age 14 and 19 years was performed. Using whole-brain voxel-based morphometry, baseline (at age 14) regional gray matter volumes (GMVs), follow-up (at age 19) regional GMVs, and longitudinal changes (between 14 and 19) associated with Morningness/Eveningness Scale in Children score and sleep habits at baseline were measured. The association of GMV with depressive symptoms at 19 years was studied, and the role of potential clinical and genetic factors as mediators and moderators was assessed.

RESULTS

Higher eveningness was associated with larger GMV in the right medial prefrontal cortex at ages 14 and 19 in the whole sample. GMV in this region related to depressive symptoms at age 19 in catechol-O-methyltransferase (COMT) Val/Val, but not in Met COMT, carriers. Larger GMV also was observed in the right fusiform gyrus at age 14, which was explained by later wake-up time during weekends.

CONCLUSION

In adolescence, eveningness and its related sleep habits correlated with distinct developmental patterns. Eveningness was specifically associated with GMV changes in the medial prefrontal cortex; this could serve as a brain vulnerability factor for later self-reported depressive symptoms in COMT Val/Val carriers.

Morning individuals in Saudi Arabia have higher self-regulation of eating behavior compared to evening types

Chronotype is a manifestation of an individual's circadian system, which can be presented as a preference for morningness or eveningness. Evening chronotype has been linked to unhealthy dietary habits. These habits are partially from poor self-regulation of eating behavior (SREB). SREB is a goal-directed process that helps resist food temptation and achieve desired dietary outcomes. It is unclear whether chronotype is associated with SREB. This study aims to investigate the association between chronotypes and SREB. A total of 599 adults (18-50 years) enrolled in this cross-sectional study. Participants received an online questionnaire that collected sociodemographic, anthropometrics, chronotype through the validated reduced Morningness-Eveningness Questionnaire (rMEQ) and SREB using the SREB Questionnaire. ANOVA, Chi-square and multivariate logistic regression were used. In adjusted models, morning types had 85% higher SREB compared to evening types (p = 0.003, OR = 1.85). Evening types found fried foods (p = 0.003), chips (p = 0.005) and French fries (p = 0.018) more tempting than morning types. These findings show a link between chronotype and SREB. Strategies focusing on SREB may help evening types improve dietary habits. Further studies are required to clarify the underlying mechanisms for these associations. This may have important implications for lifestyle and behavioral change policy.

The Effect of Chronotype on Risk-Taking Behavior: The Chain Mediation Role of Self-Control and Emotional Stability

BACKGROUND

Although previous studies indicate that chronotype might be associated with risk-taking behavior, the specific mechanism has not been thoroughly discussed. This study aimed to fill this gap by exploring the mediating role of self-control and the chain mediating role of self-control and emotional stability between chronotype and risk-taking behavior.

METHODS

A total of 547 Chinese college students between 18 and 24 years old were selected to complete the Morningness-Eveningness Questionnaire (MEQ), Self-Control Scale (SCS), Eysenck's Personality Questionnaire-neuroticism (EPQ-N), and Adolescent Risk-Taking Questionnaire: Risk Behavior Scale (ARQ-RB) to assess chronotype, risk-taking behavior, self-control, and emotional stability, respectively. Hayes' PROCESS macro for SPSS was used to test the relationships among these variables.

RESULTS

Our result showed significant positive correlations among chronotype, self-control, emotional stability, and significant negative correlations between self-control, emotional stability, and risk-taking behavior. We also found that chronotype had a significant predictive effect on risk-taking behavior in the chain mediation model. Specifically, chronotype affected risk-taking behavior through two pathways: the separate mediating role of self-control and the serial mediation pathway of self-control → emotional stability.

CONCLUSIONS

Our study provides direct evidence that chronotype is associated with risk-taking behavior. The results showed that the predictive function of chronotype was mediated by self-control and emotional stability. This study provides a new perspective on preventing and reducing risk-taking behavior.

How is circadian preference associated with cyber-victimization? A moderated mediation model of hostile recognition and online self-disclosure in Chinese early adolescent students

Although circadian preference is widely accepted to be a risk factor in the increase of adolescents’ negative experiences, little is known about its association with cyber-victimization. The current study sought to examine whether eveningness was significantly related to adolescents’ negative experiences. We further examined in-victimization events and whether hostile recognition and online self-disclosure played a vital role in eveningness and adolescents’ cyber-victimization. Study participants included 583 adolescents from four middle schools in China who completed questionnaires regarding their circadian preference, hostile recognition, online self-disclosure, and experience with cyber-victimization. Results indicated that adolescents with a high level of eveningness were more likely to experience cyber-victimization. Hostile recognition significantly mediated the relationship between eveningness and adolescents’ cyber-victimization. Furthermore, online self-disclosure moderated the indirect relationship between eveningness and cyber-victimization. Specifically, the paths from eveningness to hostile recognition and from hostile recognition to cyber-victimization became strengthened when adolescents experienced high levels of online self-disclosure. The results imply that researchers should pay more attention to remote factors, such as adolescents’ circadian preference and their relationship with cyber-victimization, to help them adapt to school requirements and reduce the frequency of victimization.

Insomnia symptoms do, but chronotype does not show relevant associations with mental well-being and negative dream experiences

Chronotypes are diversely associated with sleep quality and mental health. Eveningness is generally associated with lower sleep quality and with increased risk for mental health complaints. Along with insomnia symptoms, frequent dysphoric dreams might be key elements of disturbed sleep, and may also indicate psychological imbalance. Our cross-sectional online study aimed to examine whether eveningness can be considered as an independent risk factor of poor mental well-being or whether this association is explained by symptoms of insomnia. Secondly, we examined the associations between eveningness and frequent dysphoric dreaming taking into account the influence of mental well-being and insomnia complaints. Method: We released an online survey with Morningness-Eveningness Questionnaire, Athens Insomnia Scale, General Mental Health, and frequency of dysphoric dreaming: nightmares and bad dreams separately. We analyzed the data of 2077 participants (MAGE = 28.5, SD = 9.6). Eveningness showed a weak but independent association with mental well-being. Additional analyses showed no signs of associations between eveningness and dysphoric dreaming, such as nightmares and bad dreams. The frequency of bad dreams was associated with insomnia complaints and mental well-being, but nightmare frequency was only linked to insomnia symptoms, but not to mental well-being. Insomnia complaints emerged as a more robust factor in poorer mental well-being than the eveningness preference. Eveningness was not associated with dysphoric dreaming. Restoring insomnia might be essential in individuals at risk for mental health complaints.

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.

Chronotype Profile, Stress, Depression Level, and Temporomandibular Symptoms in Students with Type D Personality

Background: Despite a growing interest in the types of human circadian activity, different chronotypes and personality-related issues have been rarely studied. It has already been emphasized that ‘stress personality’ is considered a risk factor for certain psychosomatic diseases and may be a temporomandibular disorders (TMDs) predictor. Therefore, an attempt has been made to analyze the chronotypes, stress levels, stress factors, and the occurrence of depression and TMDs in students with type D personalities. People with this personality trait tend to experience negative emotions more—depression, anxiety, anger, or hostility—yet may have a negative image of themselves and report somatic complaints. Aim: The aim of this study was to analyze the importance of the chronotype profile for the level of stress perceived, as well as for the occurrence of depression and TMDs in people with type D personalities. Material and Methods: The study has been conducted on a group of 220 physical therapy students. The study group G1 consisted of 110 participants with type D personalities, the control group G2 consisted of the same number of participants without the stress personality. All participants have been analyzed for the chronotype (MEQ), stress perception (PSS10), the occurrence of depression (Beck scale-BDI), the occurrence of TMDs symptoms and have completed the stress factor assessment questionnaire during the study, followed by DS14 questionnaire—a tool for assessing the prevalence of type D personality. Results: In students with type D personalities (G1), the definitely evening and evening chronotypes have been significantly more predominant than in the control group (G2). A significantly higher number of stressors and TMDs symptoms have been observed in the respondents from the G1 group than in the control group (<0.001). Univariate logistic regression analysis showed that type D personality was strongly associated with a more frequent occurrence of all TMD symptoms. Additionally, a significant influence of the evening chronotype on the occurrence of type D personality was observed. Among the potential confounding variables, female gender and a mild and moderate degree of depression have an impact on the occurrence of type D personality (p < 0.05). In the multivariate model, adjusted with the above-mentioned factors, an increased risk of the type D personality trait was found. Conclusion: The evening chronotype and type D personality may imply greater feelings of stress, greater depression, and more frequent symptoms of TMDs in young adults.

Morningness-Eveningness Preference, Time Perspective, and Passage of Time Judgments

Recent studies have shown that making accurate passage of time judgments (POTJs) for long-time intervals is an important cognitive ability. Different temporal domains, such as circadian typology (biological time) and time perspective (psychological time), could have an effect on subjective POTJs, but few studies have investigated the reciprocal influences among these temporal domains. The present study is the first systematic attempt to fill this gap. A sample of 222 participants (53.20% females; 19-60 years) filled in the Zimbardo Time Perspective Inventory for the measurement of time perspective, the reduced version of the Morningness-Eveningness Questionnaire (rMEQ) for chronotypes, and an ad-hoc questionnaire assessing sleep habits during weekdays and the weekend (for social jetlag). The POTJ was measured using a modified version of a pictorial timeline presented at five different moments. Also, participants judged how different temporal expressions were related to the past, present, and future along a 7-point Likert scale. After confirming the association between eveningness and present-hedonism orientation and morningness and future-orientation, we found that evening-types produced higher scores for future expressions. The subjective POTJ expressed in minutes was predicted by Deviation from Balanced Time (DBTP), present-fatalism orientation, and social jetlag. Finally, the rMEQ score, past-positive orientation, and DBTP predicted the difference between subjective and objective POT. The results are discussed offering an explanation in terms of the interconnections between circadian typology, individual time perspective, and the sense of the POT, suggesting the multicomponent nature of the concept of time.

Chronotype, sleep quality and academic performances among Mizo students

Sleep is an essential component of the daily cycle. Age and puberty-related declines in sleep duration, delays in chronotype, and an increase in social jet lag have been consistently reported. This study examined chronotype and gender-based differences in adolescents' sleep quality, depression level, and academic achievements. Eight hundred fifteen school students (372 male and 443 female) aged 14 to 20 years voluntarily participated in this study. Horne and Östberg Morningness-Eveningness Questionnaire (MEQ) was used to measure their chronotype. Sleep duration, sleep quality, and daytime sleepiness were assessed by the Pediatric Daytime Sleepiness Scale (PDSS) and Epworth Sleepiness Scale (ESS). Pittsburgh's Sleep Quality Index (PSQI) was used to evaluate sleep habits. Cleveland Adolescent Sleepiness Questionnaire (CASQ) was used to measure the sleep pattern of the students. Zung Self-Rating Depression Scale (SDS) was used to assess the level of depression for the students. Our results show neither type of students dominated the population studied but interestingly, in comparison to evening type, morning type individuals were higher among the population. Chronotype-based sleep quality and academic performances were observed, and higher depression levels, poor sleep quality, poor academic performances were observed in evening type compared to neither type and morning type. In contrast to males, females had a poor sleep pattern (CASQ) and a higher depression level (SDS). Altogether, our study shows the effect of chronotype and gender on sleep quality and depression levels among school students.

The moderating role of personality traits in the relationship between chronotype and depressive symptoms

Due to the undeniably morning orientation of the social clock, the evening chronotype can be associated with negative consequences, both at the affective and cognitive levels. Evening-oriented individuals are more susceptible to affective disorders, show poorer educational achievements and consume stimulants more often than morning-oriented individuals. However, little is known about potential factors that may attenuate or amplify these negative emotional consequences of the evening preference. Thus, our aim was to examine whether personality traits interplay with chronotype in predicting depressive symptoms. We assessed the Big Five and the Big Two personality traits, morningness-eveningness and depressive symptoms in an online sample of 913 Polish individuals (468 females, 445 males), aged 18-35 (M = 26.34, SD = 5.15). Eveningness, higher neuroticism, lower conscientiousness and lower alpha-stability were associated with higher depressive symptoms. The magnitude of the association between eveningness and depressive symptoms decreased with higher conscientiousness and alpha-stability, as well as with lower neuroticism. In conclusion, high neuroticism, low conscientiousness and low alpha-stability increase the risk of depressive symptoms, particularly among evening chronotypes. The patients' chronotypes and personality traits should be taken into account in both the prevention and diagnostics of depression.

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.

Influence of Chronotype on Motor Behavior in Healthy Individuals: Analyses of Manual Dexterity in Different Times of the Day

This study investigated the influence of chronotype on motor behavior in a manual dexterity task performed at different times of the day. Sixteen healthy adults of each chronotype (morning, evening, and neither), as measured by the Morningness-Eveningness Questionnaire, practiced both conditions of the Grooved Pegboard Test either in the morning or in the afternoon to early evening. The "neither" chronotype (65.12 ± 7.46) was outperformed (ps ≤ .03) by both the morning (56.09 ± 7.21) and evening (58.94 ± 7.53) chronotypes when the task had higher cognitive and motor demand but was not outperformed in the task with lower demand (morning = 18.46 ± 2.11; evening = 19.34 ± 2.79; neither = 21.47 ± 2.54; p > .05). No difference between the morning and evening chronotypes was found at the different times of the day (ps > .05), suggesting that a manual dexterity task is not sufficiently demanding to be influenced by chronotype.

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.

Relationships between morningness, Big Five personality traits, and problematic Internet use in young adult university students: mediating role of depression

The aim of this study was twofold. Firstly, it explored the relationships between morningness, Big Five personality traits, depression, and problematic Internet use (PIU). Secondly, it examined the possible mediating role of depression in these relationships. The following measures were used: the Internet Addiction Test, the Composite Scale of Morningness, the International Personality Item Pool-Big Five Markers-20, and the Center for Epidemiologic Studies Depression Scale. The participants in the study were 398 university students 18 to 30 (M = 20.37, SD = 2.29) years of age. The study found that PIU Total, PIU Mental Disorder, and PIU Time Management Disorder are positively related to depression and negatively related to morningness, Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness. PIU was more often found in individuals with an evening chronotype. The study confirmed the role of depression as a mediator in the relationship of personality traits and morningness to PIU Mental Disorder and PIU Time Management Disorder. For PIU Mental Disorder, the study revealed a full mediation effect of depression in the case of morningness, Emotional Stability, and Extraversion, and partial mediation in the case of Agreeableness and Intellect. For PIU Time Management Disorder, there was a full mediation effect of depression in the case of Emotional Stability, Extraversion, and Agreeableness, and partial mediation in the case of morningness and Intellect. The results highlight the importance of including depression when investigating the relationship between morningness and personality in studies of PIU.

Nightmares, Chronotype, Urbanicity, and Personality: An Online Study

Chronotype refers to individual differences in sleep timing ("owls" and "larks") and "eveningness" has been associated with nightmares. However, it has not been tested as to whether neuroticism mediates this relationship. Urbanicity refers to being raised in an urban region and/or currently living in an urban region and is associated with heightened risk for developing mental disorders, and thus might be related to nightmare frequency and nightmare distress. Overall, 2492 persons (1437 women, 1055 men) completed an online survey between 23 March 2015 and 8 April 2015. The mean age of the sample was 47.75 ± 14.41 years. The findings indicate that the previously reported relationship between chronotype and nightmare frequency was mediated by neuroticism and "morningness" was related to higher dream recall compared to persons with a late bedtime preference. Urbanicity was not related to nightmare frequency but to lower nightmare distress, raising the interesting question as to whether beliefs about nightmares might be an important variable that contributes to nightmare distress. Based on the few studies so far, there are still many unresolved questions about the interaction between nightmares, chronotype, and urbanicity.

Morningness-eveningness preference and sensation seeking

The aim of this study was to explore the relationship between circadian preference and sensation seeking. To this aim 1041 university students (408 males and 633 females), ranging in age between 18 and 30 years, filled the reduced version of the Morningness-Eveningness Questionnaire (MEQr) and the Sensation Seeking Scale-Form V (SSS-V). Males scored higher than females in SSS-V total score and all subscales, except experience seeking (ES). As regards circadian preference, evening types scored higher than morning types in SSS-V total score and all subscales, except boredom susceptibility (BS) where they significantly differed only from intermediate types. On the whole our results highlight a significant relationship between circadian preference and sensation seeking.

Assessing Chronotypes by Ambulatory Circadian Monitoring

In order to develop objective indexes for chronotype identification by means of direct measurement of circadian rhythms, 159 undergraduate students were recruited as volunteers and instructed to wear ambulatory circadian monitoring (ACM) sensors that continuously gathered information on the individual's environmental light and temperature exposure, wrist temperature, body position, activity, and the integrated TAP (temperature, activity, and position) variable for 7 consecutive days under regular free-living conditions. Among all the proposed indexes, the night phase marker (NPM) of the TAP variable was the best suited to discriminate among chronotypes, due to its relationship with the Munich ChronoType Questionnaire (β = 0.531; p < 0.001). The NPM of TAP allowed subjects to be classified as early- (E-type, 20%), neither- (N-type, 60%), and late-types (L-type, 20%), each of which had its own characteristics. In terms of light exposure, while all subjects had short exposure times to bright light (>100 lux), with a daily average of 93.84 ± 5.72 min, the earlier chronotypes were exposed to brighter days and darker nights compared to the later chronotypes. Furthermore, the earlier chronotypes were associated with higher stability and day-night contrast, along with an earlier phase, which could be the cause or consequence of the light exposure habits. Overall, these data support the use of ACM for chronotype identification and for evaluation under free living conditions, using objective markers.

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.

Validation of the Chinese Version of the Children's ChronoType Questionnaire (CCTQ) in school-aged children

The Children's ChronoType Questionnaire (CCTQ) is a valid and reliable measure for assessing prepubertal children aged 4-11 years. The CCTQ is a parent-reported, 27-item questionnaire consisting of sleep-wake parameters for scheduled and free days (16 items), a morningness/eveningness scale (M/E, 10 items), and a five-point, single-item, chronotype score. The CCTQ has been translated into different languages, but a Chinese version is not available. In the present study, we aimed to produce a Chinese version of the CCTQ and test its validity and reliability on school-aged children. A total of 555 children aged 7-11 years were recruited from five primary schools. The parents were told to complete the CCTQ and record their child's sleep pattern in a 7-day sleep diary. Sixty-six children and their parents were invited to participate in determining the test-retest reliability of the CCTQ over a 2-week interval, and their sleep patterns were assessed using a sleep diary. The internal consistency of the Chinese CCTQ M/E score as measured by Cronbach's alpha was acceptable (0.74). Regarding the test-retest reliability of the instrument, moderate to strong Spearman's correlation coefficients were found for most of the CCTQ - sleep-wake items (ρ = 0.52-0.86) and for the CCTQ-M/E total score (ρ = 0.78). For the concurrent validity, Spearman's correlations between the sleep-wake parameters of the CCTQ and the sleep diary were moderate to high on both the scheduled days (ρ = 0.54 to 0.87) and free days (ρ = 0.36 to 0.60). For the correlations measured with actigraphs, significant correlations were found in the CCTQ sleep-wake parameters, including bedtime, get-up time, sleep latency, sleep period, time in bed, and mid-sleep point on both the scheduled (ρ = 0.31 to 0.76) and free days (ρ = 0.27 to 0.52), but not in sleep latency and sleep period on free days. The results of the present study suggest that the Chinese version of the CCTQ is a reliable and valid tool for assessing chronotypes in Chinese school-aged children in Hong Kong.

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.

Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms

Being a morning person is a behavioural indicator of a person's underlying circadian rhythm. Using genome-wide data from 697,828 UK Biobank and 23andMe participants we increase the number of genetic loci associated with being a morning person from 24 to 351. Using data from 85,760 individuals with activity-monitor derived measures of sleep timing we find that the chronotype loci associate with sleep timing: the mean sleep timing of the 5% of individuals carrying the most morningness alleles is 25 min earlier than the 5% carrying the fewest. The loci are enriched for genes involved in circadian regulation, cAMP, glutamate and insulin signalling pathways, and those expressed in the retina, hindbrain, hypothalamus, and pituitary. Using Mendelian Randomisation, we show that being a morning person is causally associated with better mental health but does not affect BMI or risk of Type 2 diabetes. This study offers insights into circadian biology and its links to disease in humans.

Digital Footprints of Sensation Seeking

Abstract. The increasing usage of new technologies implies changes for personality research. First, human behavior becomes measurable by digital data, and second, digital manifestations to some extent replace conventional behavior in the analog world. This offers the opportunity to investigate personality traits by means of digital footprints. In this context, the investigation of the personality trait sensation seeking attracted our attention as objective behavioral correlates have been missing so far. By collecting behavioral markers (e.g., communication or app usage) via Android smartphones, we examined whether self-reported sensation seeking scores can be reliably predicted. Overall, 260 subjects participated in our 30-day real-life data logging study. Using a machine learning approach, we evaluated cross-validated model fit based on how accurate sensation seeking scores can be predicted in unseen samples. Our findings highlight the potential of mobile sensing techniques in personality research and show exemplarily how prediction approaches can help to foster an increased understanding of human behavior.

Time to learn: How chronotype impacts education

A growing body of literature has linked chronotype and sleep to school performance. Chronotype is under the control of the circadian clock and refers to sleep timing and diurnal preferences. Chronotype changes with age and is latest during adolescence, giving rise to a mismatch between the (late) circadian clock and the (early) school clock. In general, evening (late) chronotypes obtain lower grades. School performance is influenced by many other factors, such as motivation, intelligence, and conscientiousness. Some of these factors also relate to chronotype. The present paper reviews the literature on the relationship between chronotype and school performance, with the aim of suggesting hypotheses about the mechanisms behind this complex phenomenon and exploring solutions for an optimized school system. Based on the literature reviewed, we hypothesize that chronotype has both a direct and an indirect effect on school performance. The indirect effect is mediated by factors such as conscientiousness, learning/achieving motivation, mood, and alertness. In addition, time of day of testing plays an important role since the chronotype effect on grades is strongest in the morning and disappears in the afternoon. Strategies to decrease the mismatch between the adolescent circadian clock and the school clock could involve light interventions to advance the students' sleep timing, delays in school starting times, and rearrangements of test schedules (tests later in the day).

Associations between chronotypes and psychological vulnerability factors of depression

Chronotypes have been associated with psychopathology. The eveningness chronotype has been consistently linked with depressed states or depressive disorder, but the underlying mechanism remains unclear. Prior studies have shown associations between chronotype and personality traits that are linked to depression (e.g. neuroticism), but other psychological vulnerability factors have not been previously investigated in relation to chronotypes. The aim of this study was to examine the association between chronotypes, depression and psychological risk factors of depression (namely, cognitive reactivity and worry), in a large cohort of depressed patients and healthy individuals. We used data from the Netherlands Study of Depression and Anxiety (n = 1654), which includes 1227 clinically diagnosed individuals with a lifetime diagnosis of depression and 427 healthy controls. We assessed cognitive reactivity (Leiden Index of Depression Sensitivity-Revised) and trait worry (Penn State Worry Questionnaire). We controlled for sociodemographic factors as well as for insomnia and neuroticism. We found that the evening type is associated with higher cognitive reactivity scores, especially with increased rumination. Cognitive reactivity also mediated the relationship between chronotype and depression status, even when controlling for neuroticism and insomnia. Trait worry was not associated with chronotype. Our findings show that depressogenic cognitions are more prevalent in evening types and perhaps mediate the association between chronotype and depression. Further prospective research is needed to determine the timeline of the association. Nevertheless, results imply that targeting depressogenic cognitive processes, perhaps in combination with chronotherapeutic treatments, may be particularly useful in evening types.

Relationship between chronotype and temperament/character among university students

Chronotype is largely classified as being morning or evening types according to preference for daily activity and the preferred bedtime. This study examined the relationship between chronotype and temperament/character dimensions among university students. A total of 2857 participants completed the 140-item Temperament and Character Inventory-Revised Short version (TCI-RS) from a 5-score scale as well as the 13-item composite scale for morningness-eveningness (CSM). In this study, we classified chronotype as "morning," "neither," or "evening" types according to CSM scores and compared the scores in terms of 4 temperament dimensions and 3 character dimensions. The evening type showed high values for novelty seeking and harm avoidance, whereas the morning type had high scores for persistence, self-directedness, and cooperativeness. A logistic regression analysis after controlling for age and gender showed that chronotype significantly associated with persistence and novelty seeking. The results of this study suggest that chronotype is different according to gender and age and in addition, chronotype closely correlates with temperament and character. Among these, eveningness was associated with high novelty seeking, whereas morningness was associated with high persistence. Further studies are required to investigate the relationship between chronotype and temperament/character dimensions in a wider age bracket.

Sleep and optimism: A longitudinal study of bidirectional causal relationship and its mediating and moderating variables in a Chinese student sample

While both sleep and optimism have been found to be predictive of well-being, few studies have examined their relationship with each other. Neither do we know much about the mediators and moderators of the relationship. This study investigated (1) the causal relationship between sleep quality and optimism in a college student sample, (2) the role of symptoms of depression, anxiety, and stress as mediators, and (3) how circadian preference might moderate the relationship. Internet survey data were collected from 1,684 full-time university students (67.6% female, mean age = 20.9 years, SD = 2.66) at three time-points, spanning about 19 months. Measures included the Attributional Style Questionnaire, the Pittsburgh Sleep Quality Index, the Composite Scale of Morningness, and the Depression Anxiety Stress Scale-21. Moderate correlations were found among sleep quality, depressive mood, stress symptoms, anxiety symptoms, and optimism. Cross-lagged analyses showed a bidirectional effect between optimism and sleep quality. Moreover, path analyses demonstrated that anxiety and stress symptoms partially mediated the influence of optimism on sleep quality, while depressive mood partially mediated the influence of sleep quality on optimism. In support of our hypothesis, sleep quality affects mood symptoms and optimism differently for different circadian preferences. Poor sleep results in depressive mood and thus pessimism in non-morning persons only. In contrast, the aggregated (direct and indirect) effects of optimism on sleep quality were invariant of circadian preference. Taken together, people who are pessimistic generally have more anxious mood and stress symptoms, which adversely affect sleep while morningness seems to have a specific protective effect countering the potential damage poor sleep has on optimism. In conclusion, optimism and sleep quality were both cause and effect of each other. Depressive mood partially explained the effect of sleep quality on optimism, whereas anxiety and stress symptoms were mechanisms bridging optimism to sleep quality. This was the first study examining the complex relationships among sleep quality, optimism, and mood symptoms altogether longitudinally in a student sample. Implications on prevention and intervention for sleep problems and mood disorders are discussed.