Overlap between individual variation in personality traits and sleep-wake behavior

The efforts to link the individual differences in personality to the individual differences in sleep-wake behavior have a long history. One of the topics of such research might be to determine the strength of association between these two domains of individual variation. This requires the implementation of several inventories designed for integrative multidimensional assessments of a set of broad personality traits and a set of sleep-wake behavioral traits. Four independent samples were collected (in total, 759 individuals) for estimating general overlap between the domains of individual variation in personality psychology and chronobiology. Canonical correlation analyses provided the estimates of general overlap of six broad personality traits assessed with the 172-word RCIP (Rugby Cake Inventory of Personality) with six distinct sleep-wake adaptabilities assessed with the 72-item SWPAQ (Sleep-Wake Pattern Assessment Questionnaire) and the SWAT (Sleep-Wake Adaptability Test) in two, the 60- and 168-item, versions. It was demonstrated that general overlap between individual variation in two domains was significant and replicable albeit rather weak (6%–8%). Moreover, regression analyses of specific overlaps of each of six scales for assessing sleep-wake adaptability with a set of six scales for personality assessment suggested that a score on any of adaptability scales seemed to be a significant predictor of, at least, one of six scores on personality trait scales. Studies in other tongues are desired for the replication of the results indicating the statistically significant general and specific overlaps between personality traits and sleep-wake adaptabilities. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature

Single-Item Chronotyping (SIC), a method to self-assess diurnal types by using 6 simple charts

Research on individual differences in the fields of chronobiology and chronopsychology mostly focuses on two – morning and evening – chronotypes. However, recent developments in these fields pointed at a possibility to extend chronotypology beyond just two chronotypes. We examined this possibility by implementing the Single-Item Chronotyping (SIC) as a method for self-identification of chronotype among six simple chart options illustrating the daily change in alertness level. Of 2283 survey participants, 2176 (95%) chose one of these options. Only 13% vs. 24% chose morning vs. evening type (a fall vs. a rise of alertness from morning to evening), while the majority of participants chose four other types (with a peak vs. a dip of alertness in the afternoon and with permanently high vs. low alertness levels throughout the day, 15% vs. 18% and 9% vs. 16%, respectively). The same 6 patterns of diurnal variation in sleepiness were yielded by principal component analysis of sleepiness curves. Six chronotypes were also validated against the assessments of sleep timing, excessive daytime sleepiness, and abilities to wake or sleep on demand at different times of the day. We concluded that the study results supported the feasibility of classification with the 6 options provided by the SIC. © 2020 Elsevier Lt