Evening types among german university students score higher on sense of humor after controlling for big five personality factors

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.

A Hindi version of the Composite Scale of Morningness

BACKGROUND

Several pen and paper measures of human circadian preference are available in English, but none are available in Hindi, hampering research in circadian behavior among Hindi speaking populations in India and elsewhere. The present study describes a Hindi version of the Composite Scale of Morningness (CSM), a self-reported questionnaire widely used to assess morningness/eveningness (M/E). M/E has been used a proxy for circadian phase in lieu of cumbersome and expensive laboratory studies.

METHOD

The thirteen item English version of the CSM was translated into Hindi and independently back translated into English. Inconsistencies between the original and back translated versions were then resolved. Both versions were next administered to bilingual persons at Delhi, India (N=130). After intra-class correlations between the Hindi and the English versions were examined, the Hindi version was administered to community based participants representing different age groups (N=310).

RESULTS

There was satisfactory intra-class correlation (ICC) between the total scores for the Hindi and the English versions of the CSM (Cronbach's alpha=0.873), with variation for individual items scores. Total CSM scores in the second sample suggested a significant association with age, consistent with published reports with the English CSM, i.e., morningness tendencies were more likely to be reported by older adults. Significant associations with gender or educational status were not observed.

CONCLUSIONS

The Hindi CSM is a brief questionnaire that provides behavioral measures of diurnal preference. It is freely available for research in Hindi speaking populations.

Of larks and hearts--morningness/eveningness, heart rate variability and cardiovascular stress response at different times of day

Inter-individual differences in the circadian period of physical and mental functions can be described on the dimension of morningness/eveningness. Previous findings support the assumption that eveningness is related to greater impulsivity and susceptibility to stress than morningness. Heart rate variability (HRV) serves as a physiological correlate of self- and emotional regulation and has not yet been investigated in relation to chronotypes. The study explores differences in HRV and other cardiovascular measures in morning- and evening-types at rest and under stress at different times of day (8-11 a.m. or 4-7 p.m.). Students (N=471) were screened for chronotype and n=55 females (27 morning- and 28 evening-types) were recruited for testing. These participants performed a mental arithmetic task while heart rate (HR) and blood pressure (BP) were recorded. Spectral components and a time-domain measure of HRV were calculated on HR data from resting and mental stress periods. Evening-types had significantly higher HR and systolic BP, but lower HRV than morning-types both at baseline and during stress. Stress induced in the evening had a significantly stronger impact on absolute and baseline corrected physiological measures in both chronotypes. The interaction of chronotype and testing time did not reach the level of significance for any of the dependent variables. The enhanced physiological arousal in evening-types might contribute to increased vulnerability to psychological distress. Hence, previous behavioral findings are supported by the physiological data of this study.

Cognitive parameters and morning and evening types: two decades of research (1990-2009)

An important area of study has examined cognitive aspects of morningness-eveningness orientation. Optimal times of efficiency in participants classified as Morning and Evening types are of great importance for understanding their cognitive abilities. The present review covers the last two decades (1990-2009), during which the important review by Tankova, Adan, and Buela-Casal appeared, and focuses particularly on attention, memory, and executive functions.

Circadian rhythms, sleep, and substance abuse

Substance abuse is linked to numerous mental and physical health problems, including disturbed sleep. The association between substance use and sleep appears to be bidirectional, in that substance use may directly cause sleep disturbances, and difficulty sleeping may be a risk factor for relapse to substance use. Growing evidence similarly links substance use to disturbances in circadian rhythms, although many gaps in knowledge persist, particularly regarding whether circadian disturbance leads to substance abuse or dependence. Given the integral role circadian rhythms play in regulating sleep, circadian mechanisms may account in part for sleep-substance abuse interactions. Furthermore, a burgeoning research base supports a role for the circadian system in regulating reward processing, indicating that circadian mechanisms may be directly linked to substance abuse independently of sleep pathways. More work in this area is needed, particularly in elucidating how sleep and circadian disturbance may contribute to initiation of, and/or relapse to, substance use. Sleep and circadian-based interventions could play a critical role in the prevention and treatment of substance use disorders.