Morningness–eveningness and temperament: The Regulative Theory of Temperament perspective Konrad S. Jankowski ⇑ University of Warsaw, Faculty of Psychology, Stawki 5/7, 00-183 Warsaw, Poland article info Article history: Received 24 January 2012 Received in revised form 17 April 2012 Accepted 25 May 2012 Available online 26 June 2012 Keywords: Morningness–eveningness Chronotype Personality Temperament abstract The aim of the present study was to test whether morningness–eveningness is related to the six dimen- sions of temperament postulated in the Regulative Theory of Temperament: briskness (BR), perseveration (PE), sensory sensitivity (SS), emotional reactivity (ER), endurance (EN), and activity (AC). A sample of 581 undergraduates (age: 21.92 ± 2.54; 381 female) completed the Morningness–Eveningness Questionnaire (MEQ) and the Formal Characteristics of Behaviour – Temperament Inventory. Data was analysed using linear and quadratic hierarchical regressions. The MEQ scores exhibited linear associations with BR and EN and quadratic relationships with PE, ER and AC. Morningness was related to high levels of EN, BR and AC and low levels of PE and ER, while eveningness was associated with low levels of EN, ER, BR and PE and high levels of AC. Subjects in the middle of the morningness–eveningness dimension exhibited high lev- els of PE and ER, low levels of AC, and average levels of EN and BR. Morningness was related to the most advantageous temperament profile, and temperament is discussed as a possible mediator between mor- ningness–eveningness and mood and affective disorders. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The morningness–eveningness dimension is a variable belong- ing to individual differences, describing individual preferences for functioning at various times of the day. Individuals differing in morningness–eveningness display differing circadian phasing of many physiological and psychological circadian rhythms. Individu- als with different morningness–eveningness levels also vary in many more individual characteristics than simply their circadian phase position. Particularly consistent relationships have been shown for mor- ningness–eveningness and affective functioning. Eveningness was associated with a disadvantageous diurnal mood profile, consisting of low energy and pleasance and high tension (Jankowski & Ciarkowska, 2008), which was similar to the profile of individuals with depressive symptoms (Wirz-Justice, 2008). Therefore, it is not surprising that eveningness has been associated with depres- sion (Chelminski, Ferraro, Petros, & Plaud, 1999) and other affective disorders (Ahn et al., 2008; Murray, Allen, & Trinder, 2003). Conse- quently, greater eveningness was associated with lower life satis- faction (Jankowski, 2012). The above observations seem to have crucial importance in studying morningness–eveningness, as they imply that individual circadian preference may influence key mea- sures of human wellbeing and happiness. The question arises what mechanisms make evening chrono- types more prone to developing disadvantageous affective states. One possible mechanism is that most evening subjects probably experience a discrepancy between their preferred time of day for work/education and the time of day that is socially acceptable for such activities. Such a discrepancy may produce symptoms similar to the jetlag syndrome observed after crossing a number of time-zones by air. To emphasize the similarity between jetlag syndrome and the discrepancy between individual and social timing, the term social jetlag was introduced (Wittmann, Dinich, Merrow, & Roenneberg, 2006). However, the discrepancy between preferred time of day and socially desirable time of day is just one of the factors that potentially influence individual affect/happi- ness/satisfaction. Another probable factor is the individual’s poten- tial for adapting to environmental requirements, particularly to functioning at undesirable times of day. Personality and temperament influence individual capacity to meet environmental requirements and are considered to modulate the impact of external factors on perceived stress, happiness and health (Strelau, 2008). Therefore, it is not surprising that individual differences in morningness–eveningness have been studied in rela- tion to personality and temperamental traits (Randler & Saliger, 2011; Tsaousis, 2010). A concept somehow unique among personality/temperament models, is the Regulative Theory of Temperament (RTT) proposed by Strelau (2008), which defines temperament as a biological basis for personality development. Based on theory assumptions and psy- chometric studies, six temperamental traits have been distinguished 0191-8869/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.paid.2012.05.034 ⇑ Tel.: +48 225549721. E-mail address: konrad.jankowski@psych.uw.edu.pl Personality and Individual Differences 53 (2012) 734–739 Contents lists available at SciVerse ScienceDirect Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid