The Relationship between Chronotype and Academic Achievement among Slovene University Students: The Mediating Role of Trait Self-Control and Sleep Quality Katarina Maučec* 1 and Vita Štukovnik 2 • Several studies have identified a relationship between an individual’s chronotype and academic performance. Specifically, individuals with a morning preference often outperform those with an evening prefer - ence. Our research explored whether trait self-control and sleep quality mediate this association. We conducted an online survey completed by Slovenian university students. Chronotype, trait self-control, and sleep quality were measured using the Morningness-Eveningness Question - naire, the Brief Self-Control Scale, and the Pittsburgh Sleep Quality In - dex. Additionally, the participants’ academic achievement was assessed using an objective measure (the average grade for the winter 2022/2023 exam period) and a subjective measure (students’ own assessment of their performance compared to their peers). The results show that all researched concepts are positively correlated. Additionally, mediation analyses revealed that trait self-control significantly mediated the rela - tionship between chronotype and both measures of academic achieve - ment. Conversely, while sleep quality did not mediate the relationship between chronotype and objective academic achievement, it did par - tially mediate the relationship between chronotype and the subjective achievement measure. These insights provide a novel comprehension of the intrinsic modalities that might link chronotype and academic performance. Keywords: chronotype, academic achievement, trait self-control, sleep quality, university students 1 *Corresponding Author. Health Promotion Center, Laško Community Health Centre, Laško, Slovenia; kmaucec12@gmail.com. 2 Faculty of Arts, University of Maribor, Maribor, Slovenia. DOI: https://doi.org/10.26529/cepsj.1790 Published on-line as Recently Accepted Paper: November 2024 c e p s Journal the relationship between chronotype and academic achievement among slovene ... 2 Povezanost kronotipa in študijske uspešnosti pri slovenskih študentih: mediatorska vloga samokontrole kot osebnostne lastnosti in kakovosti spanja Katarina Maučec in Vita Štukovnik • Številne študije so pokazale, da je posameznikov kronotip povezan z njegovo študijsko uspešnostjo. Študentje, ki imajo izražene značilnosti jutranjega tipa, so študijsko uspešnejši kot tisti, ki imajo izražene zna - čilnosti večernega tipa. Namen naše raziskave je bil ugotoviti, ali sta sa - mokontrola kot osebnostna lastnost in kakovost spanja mediatorja v tej povezavi. Izvedli smo spletno anketo, ki jo je izpolnilo 544 slovenskih študentov (56 % žensk, povprečna starost 21,6 leta, SD = 2,32). Kronotip, samokontrola kot osebnostna lastnost in kakovost spanja so bili mer - jeni z uporabo vprašalnika jutranjosti in večernosti (MEQ), kratke le - stvice samokontrole (BSCS) in pittsburgškega indeksa kakovosti spanja (PSQI). Študijsko uspešnost udeležencev smo ocenili z objektivno (tj. povprečno oceno zimskega izpitnega obdobja 2022/23) in s subjektivno mero (subjektivno oceno študijske uspešnosti v primerjavi s sovrstniki). Rezultati so pokazali, da so vsi raziskovani koncepti pozitivno poveza - ni. Mediacijske analize so pokazale, da samokontrola kot osebnostna značilnost statistično pomembno mediira odnos med kronotipom in obema merama študijske uspešnosti. Po drugi strani kakovost spanja ni mediirala odnosa med kronotipom in objektivno mero študijske uspe - šnosti, je pa delno mediirala odnos med kronotipom in subjektivno mero študijske uspešnosti. Naši rezultati nakazujejo na novo razumeva - nje mehanizmov, ki povezujejo kronotip in študijsko uspešnost. Ključne besede: kronotip, študijska uspešnost, samokontrola kot osebnostna značilnost, kakovost spanja, študentje c e p s Journal 3 Introduction Circadian rhythms, intrinsic biological oscillators, govern a multitude of physiological processes and behavioural activities in living organisms, synchro - nising them with the environmental 24-hour day-night cycle (Vitaterna et al., 2001). A pertinent manifestation of these rhythms in humans is the chronotype, representing an individual’s preferential timing for periods of activity and rest, which subsequently influences diverse aspects of daily functioning and overall well-being (Adan et al., 2012). Individuals typically ascribe to one of two predominant chronotypes: morning and evening types. Morning types demonstrate a predilection for earlier periods of peak activity, preferring earlier times for sleep and waking. Conversely, evening types exhibit a propensity for later activity peaks, typically adhering to later sleep and waking schedules (Wittmann et al., 2006). Research indicates that an individual’s chronotype goes beyond merely dictating their daily preferences; it can significantly affect various aspects of mental and physical health, creating a wide range of individual differences. Im - portantly, people who are naturally inclined towards ‘eveningness’ have been found to experience various challenges. Such challenges include mental health issues such as depression and anxiety (Partonen, 2015), as well as behaviours like acting on impulse and taking risks (Fabbian et al., 2016). Furthermore, a substantive body of evidence fortifies the relationship between chronotype and academic achievement. The data suggests a notable trend of superior academic performance among morning types in comparison to their evening-type coun - terparts within university student populations (Enright & Refinetti, 2017; Mir - ghani, 2017; Montaruli et al., 2019; Tonetti et al., 2015). Nevertheless, a limited number of studies do not support this trend in certain age groups. Specifically, Figueiredo (2023) has demonstrated that morning and evening types in pri - mary school do not differ in academic performance in the subjects of math and Portuguese. A meta-analysis conducted by Preckel et al. (2011), however, elucidates that the relationship between chronotype and academic achievement operates independently of age, while another by Tonetti et al. (2015) reveals the stability of this association across both genders. Researchers have worked to understand how chronotype and academic achievement are connected, exploring factors like learning motivation and daily sleepiness as possible links between them. For instance, a susceptibility to reduced learning motivation and heightened daily sleepiness among evening types has been documented, which, in turn, poses detriments to their academic attainments (Roeser et al., 2013). High school students who report attenuated the relationship between chronotype and academic achievement among slovene ... 4 alertness during diurnal hours also manifest heightened levels of depressive moods, which is concomitantly associated with suboptimal academic perfor - mance (Short et al., 2013). Additionally, the influence of personality traits has been implicated in mediating the relationship between chronotype and academic performance. Specifically, ‘morningness’ is associated with proactive behaviours, notably ele - vated conscientiousness (Rahafar et al., 2016), which has been identified as a pre - dictor of academic achievement (Arbabi et al., 2015). Another personality trait that may elucidate these discrepancies is self-control, although research scru - tinising its role in the relationship between chronotype and academic achieve - ment is scant. Trait self-control, characterised as the capacity to modulate one’s responses to align with standards such as ideals, values, morals, and societal expectations and to facilitate the pursuit of longitudinal goals (Baumeister et al., 2007), has been illustrated to be more prominent among morning types (Digdon & Howell, 2008; Milfont & Schwarzenthal, 2014; Przepiórka et al., 2019; Wang, 2014). Furthermore, trait self-control is a critical determinant of academic prosperity. Wang and Hu (2015) offer a potential explanation for the association between chronotype and trait self-control through the lens of so - cial jet lag, wherein societal demands conflict with individual sleep preferences, creating discrepancies and inducing social jet lag. Consequently, evening types, requiring amplified effort to manage daily societal demands, may deplete their self-control resources, culminating in diminished self-control (Baumeister et al., 1994). An alternative explanatory framework posits that the positive cor - relation between morningness and trait self-control may be attributable to re - duced bedtime procrastination among morning types (Wang & Hu, 2015), as higher trait self-control is inversely related to bedtime procrastination among tertiary education students (Bernecker & Job, 2020; Zhang et al., 2023). Several personality traits, including impulsiveness, sensation-seeking, and persistence, are concomitantly associated with both chronotype and trait self-control. Even - ing types exhibit heightened impulsiveness (Kang et al., 2015; Selvi et al., 2011; Selvi et al., 2015) and sensation-seeking (Prat & Adan, 2013), while higher trait self-control is inversely associated with impulsiveness (Mao et al., 2018) and sensation-seeking (Pokhrel et al., 2010). Moreover, a positive correlation exists between morningness and persistence (Caci et al., 2004; Lee et al., 2017) and, similarly, between persistence and trait self-control (Gordeeva et al., 2017). Empirical evidence substantiates that university students manifesting higher trait self-control also exhibit enhanced academic success (King & Gaer - lan, 2013; Stadler et al., 2016). Trait self-control predicts academic achievement, transcending cognitive ability, and forecasts both objective (e.g., grade point c e p s Journal 5 average) and subjective academic achievement metrics, whereas cognitive ability solely predicts objective academic achievement indicators (Stadler et al., 2016). Given the association of trait self-control with both chronotype and academic achievement, it is plausible that trait self-control could mediate the relationship between these two constructs. People with different chronotypes also show distinct differences in their quality of sleep. The concept of sleep quality, despite lacking a universally ac - cepted definition (Ohayon et al., 2017), is discernible through various parameters such as subjective sleep quality, sleep latency, duration, efficiency, disturbances, use of sleep medication, and daytime dysfunction (Buysse et al., 1989). A body of research underscores a predilection towards suboptimal sleep quality among individuals exhibiting eveningness as opposed to morningness (Bavarsad et al., 2015; Carciofo et al., 2014; Kabrita et al., 2014; Vollmer et al., 2017). Individuals exhibiting a preference for morningness frequently demonstrate an augmented daily lifestyle regularity, a characteristic that has been positively correlated with enhanced sleep quality (Monk et al., 2004; Monk et al., 2003). A study by Taillard et al. (2002) illustrates that evening types, in contrast, typically exhibit a vari - ability exceeding two hours in both bedtime and waking times compared to their morning-type counterparts. Moreover, evening types report heightened difficul - ties in sleep initiation (Sun et al., 2019) alongside an increased prevalence of in - somnia symptoms and nightmares (Merikanto et al., 2012), all of which are fac - tors inherently associated with reduced sleep quality (Bollu & Kaur, 2019; Paul et al., 2015; Yi et al., 2006). Furthermore, evening types harbour more dysfunctional beliefs regarding sleep (Adan et al., 2006; Ong et al., 2007), and the modification of such beliefs via cognitive-behavioural therapy has been demonstrated to en - hance subjective sleep quality (Edinger et al., 2001). Additionally, a positive correlation exists between sleep quality and aca - demic achievement, as substantiated by multiple studies (El Hangouche et al., 2018; Gomes et al., 2011; Mirghani et al., 2015; Wong et al., 2013). Suboptimal sleep quality also tends to result in elevated daytime sleepi - ness (Zailinawati et al., 2009), which has been inversely associated with aca - demic achievement (Bahammam et al., 2012). Numerous studies have linked trait self-control and sleep quality to both chronotype and academic achievement, albeit without exploring their potential mediating roles in this relationship. This study seeks to elucidate the underlying mechanisms correlating chronotype with academic achievement, questioning the attribution to biological predisposition and considering alternative media - tors such as personality traits and sleep factors. We examine whether lower academic performance in university students preferring eveningness could the relationship between chronotype and academic achievement among slovene ... 6 be attributed not directly to chronotype but mediated by trait self-control and sleep quality. Thus, this research aims to explore the mediating roles of trait self-control and sleep quality in the association between chronotype and aca - demic success in a sample of Slovenian university students. Maučec and col - leagues (2023) initially presented the study’s preliminary results at the eSleep Europe Virtual Congress 2023. This article now unveils the expanded findings. The hypotheses addressed in this study are: 1. The association between chronotype and academic achievement is me - diated by self-control in a sample of Slovenian university students. 2. The association between chronotype and academic achievement is me - diated by sleep quality in a sample of Slovenian university students. Method Participants The sample was comprised of 544 Slovenian university students (56.1% female; M = 21.61 years, SD = 2.32), spanning various universities and faculties, with the majority being undergraduate students (67.2%). We included univer - sity students who achieved grades during the winter semester 2022/23. Instruments The Morningness-Eveningness Questionnaire (Horne & Ostberg, 1976): A 19-item measure capturing aspects of morningness across sleep habits, sleepi - ness, and optimal functioning times. The questionnaire utilises 1 to 5-point scales within its multiple-choice questions, with cumulative scores ranging from 16 to 86, categorising respondents into extreme evening type (16–30), moderately evening type (31–41), intermediate type (42–58), moderately morn - ing type (59–69), and extreme morning type (70–86). The Slovenian version demonstrates a Cronbach alpha of 0.86 and a test-retest reliability of 0.96 (Tre - ven Pišljar et al., 2019). The Brief Self-Control Scale (Tangney et al., 2004): A 13-item instrument assessing trait self-control, with items rated on a 5-point Likert scale and higher scores indicating greater self-control. The Slovenian adaptation shows a Cron - bach alpha of 0.77 (Zorjan, 2014). The Pittsburgh Sleep Quality Index (PSQI; Buysse et al., 1989): A measure evaluating sleep quality across seven domains: subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbances, use of sleep medica - tion, and daytime dysfunction, using 19 questions. Focusing on sleep quality in the past month, scores are calculated with a specific algorithm and combined to c e p s Journal 7 produce seven composite scores and a global sleep quality score. While lower scores denote better sleep quality, a score above 5 distinguishes poor sleepers (Buysse et al., 1989). The Slovenian version of the PSQI used in our study has a Cronbach’s alpha of 0.68 (Košir, 2021). The Objective Academic Achievement: Assessed through students’ aver - age grades during the winter semester of 2022/23. The Subjective Academic Achievement: This was evaluated using a 5-point Likert scale question regarding students’ self-perception of academic perfor - mance relative to peers in the winter semester of 2022/23. Research design Conducted from February 20 th to March 5 th , 2023, this prospective cross- sectional study utilised an online survey distributed via social media platforms, university newsletters, and email. Informed consent was obtained from each participant prior to survey initiation. All participants anonymously reported their demographic data, responded to standardised questionnaires, and could withdraw at any point without consequence. Participation was voluntary. Ad - herence to the Declaration of Helsinki was maintained throughout the study. Initial analyses encompassed descriptive statistics and frequency analy - ses for demographic data. The representation of chronotypes and the percent - age of participants scoring above 5 on the PSQI were calculated. Skewness and kurtosis coefficients verified the normal distribution of data, adhering to crite - ria set by Hair et al. (2010). With subsequent Pearson correlation coefficient analyses, we explored relationships between variables, followed by a mediation analysis, employing the PROCESS macro ver. 3.5 (Hayes, 2013). Full or partial mediation models were subjected to Sobel test verification for statistical significance. Analyses were conducted using IBM SPSS ver. 21 (IBM Corp, 2019). Results Table 1 presents the descriptive statistics for chronotype, trait self-con - trol, sleep quality, subjective academic achievement, and objective academic achievement (average grade). In terms of chronotype distribution, 3.7% of participants identified as extreme evening types, 19.7% as moderately evening types, 59.7% as intermediate types, 14.2% as moderately morning types, and 2.8% as extreme morning types. Based on the PSQI criterion (a score > 5) de - noting poor sleep quality (as per Buysse et al., 1989), 65.9% of the university students in our sample qualified as poor sleepers. the relationship between chronotype and academic achievement among slovene ... 8 Table 1 Descriptive statistics of the study variables M SD Min Max Skewness Kurtosis Cronbach alpha Chronotype 48.64 10.04 24 81 0.19 -0.07 0.86 Trait self-control 41.46 8.47 17 61 0.05 -0.53 0.83 Sleep quality 6.00 2.90 1 17 0.97 1.03 0.67 Subjective academic achievement 3.42 1.04 1 5 -0.24 -0.35 - Average grade 8.37 0.93 6 10 -0.36 -0.28 - Note. M = average; SD = standard deviation; min = minimum; max = maximum Chronotype = Morning- ness-Eveningness Questionnaire total score; Trait self-control = Brief Self-Control Scale; Sleep quality = Pittsburgh Sleep Quality Index; Average grade = objective academic achievement. The relationships between chronotype, trait self-control, sleep quality, and objective and subjective academic achievement Table 2 presents statistically significant correlations among all variables. According to Dancey and Reidy (2007), all correlation coefficients were of low magnitude, with the exception of those between objective and subjective measures of academic achievement. Specifically, morningness showed a posi - tive correlation with trait self-control and sleep quality. Additionally, morning - ness exhibited positive correlations with both subjective academic achievement and average grade. Furthermore, both measures of academic achievement demonstrated positive correlations with trait self-control and with sleep quality. Tabl e 2 Pearson correlation coefficients of studied variables Chronotype Trait self-control Sleep quality Subjective academic achievement Average grade Chronotype - Trait self-control 0.37** - Sleep quality -0.16** -0.30** - Subjective academic achievement 0.18** 0.36** -0.14** - Average grade 0.14** 0.28** -0.10* 0.57** - Note. * p < .05; ** p < .01; Chronotype = Morningness-Eveningness Questionnaire; Trait self-control = Brief Self-Control Scale; Sleep quality = Pittsburgh Sleep Quality Index; Average grade = objective academic achievement. c e p s Journal 9 Mediational role of trait self-control and sleep quality in the relationship between chronotype and academic achievement We aimed to explore the relationship between chronotype and academic achievement among university students. In the analysis examining the media - tional role of trait self-control, a significant total effect was observed between chronotype and subjective academic achievement. Both Path A (representing the effect of chronotype on trait self-control) and Path B (representing the ef - fect of trait self-control on subjective academic achievement) were statistically significant. Notably, when incorporating trait self-control into the relationship between chronotype and subjective academic achievement, the direct effect became non-significant. Further, the Sobel test yielded a t-value of 6.33 with p < 0.001, indicating that trait self-control serves as a complete mediator in the relationship between chronotype and subjective academic achievement, as depicted in Figure 1. Figure 1 Mediational role of trait self-control in the relationship between chronotype and subjective academic achievement (Maučec et al., 2023) In the examination of the mediational role of trait self-control concern - ing the relationship between chronotype and average grade (objective academic achievement), a noteworthy total effect was observed between chronotype and average grade. Additionally, Path B, representing the impact of trait self-control on av - erage grade, was found to be significant. However, upon introducing trait self- control into the relationship between chronotype and average grade, the direct effect proved non-significant. The Sobel test further corroborated the indirect effect with a value of t =5.01 and p < 0.001. Consequently, it can be inferred that the relationship between chronotype and average grade is entirely mediated through trait self-control, as illustrated in Figure 2. the relationship between chronotype and academic achievement among slovene ... 10 Figure 2 Mediational role of trait self-control in the relationship between chronotype and average grade (Maučec et al., 2023) In examining the mediating role of sleep quality between chronotype and subjective academic achievement, our results indicate significant associa - tions for both Path A (i.e., the effect of chronotype on sleep quality) and Path B (i.e., the effect of sleep quality on subjective academic achievement). Nota - bly, the introduction of sleep quality into the relationship between chronotype and subjective academic achievement rendered the direct effect significant. The Sobel test further substantiates the indirect effect with a value of t = 2.37 and p = 0.02. Consequently, the data suggests that sleep quality serves as a par - tial mediator in the relationship between chronotype and subjective academic achievement (refer to Figure 3). Figure 3 Mediational role of sleep quality in the relationship between chronotype and subjective academic achievement (Maučec et al., 2023) In our investigation into the potential mediating effect of sleep qual - ity on the relationship between chronotype and average grade, we found that c e p s Journal 11 Path B (i.e., the effect of sleep quality on average grade) lacked significance. Subsequently, introducing sleep quality into the relationship between chrono - type and average grade resulted in an insignificant direct effect. Based on these findings, we infer that the relationship between chronotype and average grade operates independently of sleep quality (refer to Figure 4). Figure 4 Mediational role of sleep quality in the relationship between chronotype and average grade (Maučec et al., 2023) Discussion In this study, we aimed to elucidate the underlying mechanisms poten - tially linking chronotype with academic achievement. Specifically, our focus was on the mediating roles of trait self-control and sleep quality. While numer - ous studies have established a connection between these two constructs and the interplay of chronotype and academic achievement (Bavarsad et al., 2015; Dig - don & Howell, 2008; El Hangouche et al., 2018; Stadler et al., 2016), none have explored the potential mediating roles of trait self-control and sleep quality in this relationship. Our investigation aimed to augment the current understand - ing of the intricate mechanisms underpinning the aforementioned association. Our study demonstrates a positive association between morningness and aca - demic achievement, measured using both objective and subjective measures. Consistent with prior research, we found that morning types outperform their evening-type counterparts academically (Enright & Refinetti, 2017; Mirghani, 2017; Montaruli et al., 2019; Preckel et al., 2011). Morning types exhibit less daily sleepiness and greater academic motivation, which correlates with improved outcomes (Roeser et al., 2013). Conversely, evening types often show lower con - scientiousness levels, a trait crucial for academic success (Arbabi et al., 2015; Rahafar et al., 2016). the relationship between chronotype and academic achievement among slovene ... 12 Furthermore, our results indicate a significant positive association be - tween chronotype, trait self-control, and academic achievement, with the latter assessed using objective and subjective measures. This observation is consistent with previous literature, which has also highlighted that individuals with morning tendencies generally demonstrate enhanced trait self-control (Digdon & Howell, 2008; Milfont & Schwarzenthal, 2014; Przepiórka et al., 2019) and that university students who exhibit higher levels of trait self-control tend to achieve superior academic outcomes (King & Gaerlan, 2013; Stadler et al., 2016). Moreover, in our study, trait self-control fully mediates the relationship between chronotype and academic achievement. To the best of our knowledge, this latter finding might provide a new perspective, possibly illuminating a previously unidentified mech - anism that connects chronotype with academic achievement. It suggests that in - dividuals with a morning preference are adept at modulating their responses, fa - vouring strategies that support the achievement of long-term objectives. This can potentially facilitate more effective learning and better academic performance. Conversely, evening chronotypes demonstrate reduced self-control, which could contribute to their lower academic outcomes. Current literature affirms that indi - viduals with an evening chronotype manifest heightened impulsivity (Kang et al., 2015; Selvi et al., 2011; Selvi et al., 2015), increased sensation-seeking behaviours (Prat & Adan, 2013), and lack of persistence (Caci et al., 2004; Lee et al., 2017). These behavioural patterns suggest a predisposition towards lower self-control traits (Gordeeva et al., 2017; Mao et al., 2018; Pokhrel et al., 2010) and collectively suggest a potential hindrance to academic success for evening chronotypes. Additionally, recent studies have highlighted an increasing trend of problematic phone usage prevalent among university students with evening chronotypes (Randjelovic et al., 2021). This factor could further compromise the academic performance of the evening-oriented individuals (Hawi & Sama - ha, 2016; Tian et al., 2021). Notably, this behaviour is also correlated with trait self-control (Servidio, 2019). Moreover, societal norms often do not align with the sleep patterns preferred by evening chronotypes, resulting in mismatches that lead to phe - nomena like social jet lag (Wang & Hu, 2015). This misalignment implies that evening-oriented individuals may need to expend additional effort to navigate daily societal obligations, potentially depleting their reservoir of self-control and thereby undermining their ability to modulate their responses (Baumeister et al., 1994). It is noteworthy that students possessing robust self-control also tend to procrastinate less (Steel, 2007), manage their study schedules efficiently, complete assignments punctually (Zhao et al., 2021), and consequently, often attain superior academic grades (Stadler et al., 2016). c e p s Journal 13 In summary, the current findings contribute to a novel understanding of possible underlying mechanisms explaining why morning types attain superior grades compared to evening types. Our study reveals that this phenomenon might not be primarily attributable to biological predisposition but is instead associated with personality traits. In this research, we were also interested in investigating the potential role of sleep quality in the relationship between chronotype and academic per - formance. Our findings provide empirical evidence suggesting a positive cor - relation between sleep quality among university students and their academic achievement. Furthermore, it was observed that individuals with enhanced sleep quality predominantly exhibit morning characteristics. This aligns with previous research demonstrating that evening types often exhibit inferior sleep quality (Bavarsad et al., 2015; Carciofo et al., 2014; Kabrita et al., 2014; Vollmer et al., 2017). In addition, compromised sleep quality has been identified as a risk factor for decreased academic performance (El Hangouche et al., 2018; Gomes et al., 2011; Mirghani et al., 2015; Wong et al., 2013). Previous research has shown that evening types frequently demonstrate augmented daily lifestyle regularity (Monk et al., 2004; Monk et al., 2003), height - ened difficulties in sleep initiation (Sun et al., 2019), greater variability in both bedtime and waking times (Taillard et al., 2002) and increased prevalence of insomnia symptoms and nightmares (Merikanto et al., 2012). These are all fac - tors associated with reduced sleep quality (Bollu & Kaur, 2019; Paul et al., 2015; Yi et al., 2006) and sleep quality is positively related to academic achievement. Therefore, we hypothesised that sleep quality mediates the relationship between chronotype and academic achievement as measured with objective and subjec - tive measures. However, our results do not fully support our hypothesis. Our research underscores the significance of chronotype in its relationship with ob - jective academic performance, regardless of the quality of sleep. This suggests that contrary to trait self-control, sleep quality does not mediate the relationship between chronotype and objective academic achievement. Correspondingly, Okano et al. (2019) found that although chronotype significantly impacted aca - demic achievement, sleep quality did not play a significant role. Although sleep quality can influence academic performance, its significance diminishes when other factors are considered. Önder et al. (2014) explored various academic pre - dictors, noting that sleep quality was not a primary factor, whereas traits like con - scientiousness, academic motivation, and social jetlag were more predictive. The researchers also found that university students who are morning types tend to be more conscientious, exhibit higher academic motivation, and accrue less sleep debt compared to their evening counterparts. Such attributes make them more the relationship between chronotype and academic achievement among slovene ... 14 likely to excel academically. Furthermore, morning types tend to be more future- oriented, displaying greater strategic behaviour and a willingness to delay gratifi - cation, as highlighted by Stolarski et al. (2013). Supporting this, Peters et al. (2005) identified the foresight of future consequences as a more significant predictor of academic success than sleep quality alone. Nevertheless, our research indicates that sleep quality does play a partial mediating role in the association between chronotype and perceived academic success. This indicates that while sleep quality influences the observed relation - ship, it does not provide a complete explanation of the dynamics between these factors. This finding highlights the complex interdependencies among chrono - type, sleep quality, and academic performance measures. Further research is needed to elucidate the reasons why sleep quality is a partial mediator in the re - lationship between chronotype and subjective academic achievement but does not mediate the connection with objective academic metrics. Conclusions Our findings underscore the significant roles of trait self-control and sleep quality in mediating the relationship between chronotype and academic achievement. When accounting for trait self-control, chronotype ceases to be a direct predictor of academic achievement. Nevertheless, chronotype remains an important predictor when considered alongside sleep quality. Our study introduces a fresh perspective on the determinants of academic achievement, suggesting that it might be less influenced by chronotype and more by person - ality aspects, notably trait self-control. These findings suggest that future re - search should continue to explore personality traits and behaviours that might influence this dynamic. This complements previous research, which identi - fied personality traits, like conscientiousness, as pivotal in elucidating the link between chronotype and academic performance. Regarding sleep quality, our study highlights the intricate interplay between sleep quality, chronotype, and academic performance, revealing a complex association that warrants further investigation to fully understand its implications for educational strategies and student well-being. As with every study, this one also has a few limitations. Given the cross- sectional nature of our study, causality cannot be established, and longitudinal studies are required to probe the causal pathways involved. Longitudinal stud - ies could examine how changes in self-control and sleep quality over time cor - respond to academic outcomes across different chronotypes. Our reliance on self-reported data, particularly concerning sleep quality and academic grades, c e p s Journal 15 is a limitation that future research should address through objective measures. Furthermore, exploring the impact of exam timings could offer a more nuanced understanding of these relationships. This is especially relevant, given studies suggest that the time of day can influence the interplay between chronotype and academic performance (Zerbini & Merrow, 2017). For enhanced preci - sion, future studies might consider incorporating a more extensive collection of grades. Future studies should consider the complex interdependencies between chronotype, academic behaviours, and personality traits also to better inform interventions aimed at improving academic performance. Our findings reveal the importance of considering individual differences in chronotype and self- regulation when designing educational strategies and support services for stu - dents. Additionally, developing programs that build self-regulatory skills could possibly help improve academic outcomes. Promoting good sleep hygiene prac - tices might also be important, considering the link between sleep quality and perceived academic success. References Adan, A., Archer, S. N., Hidalgo, M. P ., Di Milia, L., Natale, V ., & Randler, C. (2012). Circadian typol - ogy: a comprehensive review. Chronobiology International, 29(9), 1153–1175. https://doi.org/10.3109/07420528.2012.719971 Adan, A., Fabbri, M., Natale, V ., & Prat, G. (2006). Sleep Beliefs Scale (SBS) and circadian typology. Journal of Sleep Research, 15 (2), 125–132. https://doi.org/10.1111/j.1365-2869.2006.00509.x Arbabi, T., Vollmer, C., Dörfler, T., & Randler, C. (2015). The influence of chronotype and intelligence on academic achievement in primary school is mediated by conscientiousness, midpoint of sleep and motivation. Chronobiology International, 32(3), 349–357 . https://doi.org/10.3109/07420528.2014.980508 Bahammam, A. S., Alaseem, A. M., Alzakri, A. A., Almeneessier, A. S., & Sharif, M. M. (2012). The relationship between sleep and wake habits and academic performance in medical students: a cross- sectional study. BMC Medical Education, 12(1), 1–6. https://doi.org/10.1186/1472-6920-12-61 Baumeister, R. F., Vohs, K. D., & Tice, D. M. (2007). The Strength Model of Self- Control. Current Directions in Psychological Science, 16(6), 351–355. https://doi.org/10.1111/j.1467-8721.2007.00534.x Bavarsad, M. B., Azimi, N., Moradbeigi, K., & Latifi, M. (2015). Associations between morningness- eveningness and sleep quality among female dormitory residents. Sleep, 4(1). https://doi.org/10.5812/thrita.25088 Bernecker, K., & Job, V . (2020). Too exhausted to go to bed: Implicit theories about willpower and stress predict bedtime procrastination. British Journal of Psychology, 111 (1), 126–147. https://doi.org/10.1111/bjop.12382 Bollu, P . C., & Kaur, H. (2019). Sleep medicine: insomnia and sleep. Missouri Medicine, 116(1), 68–75. the relationship between chronotype and academic achievement among slovene ... 16 Buysse, D. J., Reynolds III, C. F., Monk, T. H., Berman, S. R., & Kupfer, D. J. (1989). The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Research, 28(2), 193–213. https://doi.org/10.1016/0165-1781(89)90047-4 Caci, H., Robert, P. , & Boyer, P. (2004). Novelty seekers and impulsive subjects are low in morningness. European Psychiatry, 19(2), 79–84. https ://doi.org/10.1016/j.eurpsy.2003.09.007 Carciofo, R., Du, F ., Song, N., & Zhang, K. (2014). Mind Wandering, Sleep Quality, Affect and Chronotype: An Exploratory Study. PLoS one, 9(3). https://doi.org/10.1371/journal.pone.0091285 Dancey, C. P ., & Reidy, J. (2007). Statistics without maths for psychology. Pearson Education. Digdon, N. L., & Howell, A. J. (2008). College students who have an eveningness preference report lower self‐control and greater procrastination. Chronobiology International, 25(6), 1029–1046. https://doi.org/10.1080/07420520802553671 Edinger, J. D., Wohlgemuth, W . K., Radtke, R. A., Marsh, G. R., & Quillian, R. E. (2001). Does cognitive-behavioral insomnia therapy alter dysfunctional beliefs about sleep?. Sleep, 24(5), 591–599. https://doi.org/10.1093/sleep/24.5.591 El Hangouche, A. J., Jniene, A., Aboudrar, S., Errguig, L., Rkain, H., Cherti, M., & Dakka, T. (2018). Relationship between poor quality sleep, excessive daytime sleepiness and low academic performance in medical students. Advances in Medical Education and Practice, 9, 631–638. https://doi.org/10.2147/AMEP .S162350 Enright, T., & Refinetti, R. (2017). Chronotype, class times, and academic achievement of university students . Chronobiology International, 34(4), 445–450. https://doi.org/10.1080/07420528.2017.1281287 Fabbian, F., Zucchi, B., De Giorgi, A., Tiseo, R., Boari, B., Salmi, R., Cappadona, R., Gianesini, G., Bassi, E., Signani, F., Raparelli, V ., Basili, S., & Manfredini, R. (2016). Chronotype, gender and general health. Chronobiology International, 33(7), 863–882. https://doi.org/10.1080/07420528.2016.1176927 Figueiredo, S. (2024). Chronotypes, Disruptive Behaviour, and Schedules in Classrooms: ‘Morningness’ and Psychomotor Agitation. Center for Educational Policy Studies Journal, 14 (2), 131–154. https://doi.org/10.26529/cepsj.1454 Gomes, A. A., Tavares, J., & de Azevedo, M. H. P . (2011). Sleep and Academic Performance in Under- Sleep and Academic Performance in Under - graduates: A Multi-measure, Multi-predictor Approach. Chronobiology International, 28(9), 786–801. https://doi.org/10.3109/07420528.2011.606518 Gordeeva, T. O., Osin, E. N., Suchkov, D. D., Ivanova, T. Y ., Sychev, O. A., & Bobrov, V . V . (2017). Self-Control as a personal resource: determining its relationships to success, perseverance, and well- being. Russian Education in Society, 59(5-6), 231–255. https://doi.org/10.1080/10609393.2017 .1408367 Hair, J., Black, W . C., Babin, B. J., & Anderson, R. E. (2010). Multivariate data analysis (7th ed.). Pearson Educational International. Hawi, N. S., & Samaha, M. (2016). To excel or not to excel: strong evidence on the adverse effect of smartphone addiction on academic performance. Computers & Education, 98, 81–89. https://doi.org/10.1016/j.compedu.2016.03.007 Hayes, A. F . (2013). Introduction to mediation, moderation, and conditional process analysis: a regression-based approach. Guilford Press. c e p s Journal 17 Horne, J. A., & Östberg, O. (1976). A self-assessment questionnaire to determine morningness- eveningness in human circadian rhythms. International Journal of Chronobiology, 4 , 97–110. Kabrita, C. S., Hajjar-Muça, T. A., & Duffy, J. F. (2014). Predictors of poor sleep quality among Leba - nese university students: association between evening typology, lifestyle behaviors, and sleep habits. Nature and Science of Sleep, 6, 11–19. https://doi.org/10.2147/nss.s55538 Kang, J. I., Park, C. I., Sohn, S. Y ., Kim, H. W ., Namkoong, K., & Kim, S. J. (2015). Circadian prefer - ence and trait impulsivity, sensation-seeking and response inhibition in healthy young adults. Chronobiology International, 32(2), 235–241. https://doi.org/10.3109/07420528.2014.965313 King, R. B., & Gaerlan, M. J. M. (2013). High self-control predicts more positive emotions, better engagement, and higher achievement in school. European Journal of Psychology of Education, 29 (1), 81–100. https://doi.org/10.1007/s10212-013-0188-z Košir, T. (2021). Psychometric Properties of the Slovene Version of the Pittsburgh Sleep Quality Index. [Master thesis, University of Maribor]. Digital library of University of Maribor. https://dk.um.si/IzpisGradiva.php?lang=slv&id=78946 Lee, K., Lee, H. K., Jhung, K., & Park, J. Y . (2017). Relationship between chronotype and tempera - ment/character among university students. Psychiatry Research, 251, 63–68. https://doi.org/10.1016/j.psychres.2017.01.071 Mao, T., Pan, W ., Zhu, Y ., Y ang, J., Dong, Q., & Zhou, G. (2018). Self-control mediates the relationship between personality trait and impulsivity. Personality and Individual Differences, 129, 70–75. https://doi.org/10.1016/j.paid.2018.03.013 Maučec, K., Košir, K., & Štukovnik, V . (2023, October 4–6). Chronotype and academic achievement in university students: is there a mediating role of self-control and sleep quality? [Poster presentation]. eSleep Europe Virtual Congress 2023, Regensburg, Germany. https://esleepeurope.eu/wp-content/uploads/2023/09/CHRONOTYPE-AND-ACADEMIC- ACHIEVEMENT-IN-UNIVERSITY-STUDENTS-IS-THERE-A-MEDIATING-ROLE-OF-SELF- CONTROL-AND-SLEEP-QUALITY_.pdf Merikanto, I., Kronholm, E., Peltonen, M., Laatikainen, T., Lahti, T., & Partonen, T. (2012). Relation of Chronotype to Sleep Complaints in the General Finnish Population. Chronobiology International, 29(3), 311–317. https://doi.org/10.3109/07420528.2012.655870 Milfont, T. L., & Schwarzenthal, M. (2014). Explaining why larks are future-oriented and owls are present-oriented: self-control mediates the chronotype–time perspective relationships. Chronobiology International, 31(4), 581–588. https://doi.org/10.3109/07420528.2013.876428 Mirghani, H. O. (2017). The effect of chronotype (morningness/eveningness) on medical students’ academic achievement in Sudan. Journal of Taibah University Medical Sciences, 12 (6), 512–516. https://doi.org/10.1016/j.jtumed.2017.03.007 Mirghani, H. O., Mohammed, O. S., Almurtadha, Y . M., & Ahmed, M. S. (2015). Good sleep quality is associated with better academic performance among Sudanese medical students. BMC Research Notes, 8(1), 1–5. https://doi.org/10.1186/s13104-015-1712-9 Monk, T. H., Buysse, D. J., Potts, J. M., DeGrazia, J. M., & Kupfer, D. J. (2004). Morningness-evening - the relationship between chronotype and academic achievement among slovene ... 18 ness and lifestyle regularity. Chronobiology International, 21(3), 435–443. https://doi.org/10.1081/CBI-120038614 Monk, T. H., Reynolds, C. F., Buysse, D. J., DeGrazia, J. M., & Kupfer, D. J. (2003) . The Relationship Between Lifestyle Regularity and Subjective Sleep Quality. Chronobiology International, 20(1), 97–107. https://doi.org/10.1081/cbi-120017812 Montaruli, A., Castelli, L., Galasso, L., Mulè, A., Bruno, E., Esposito, F., Caumo, A., & Roveda, E. (2019). Effect of chronotype on academic achievement in a sample of Italian university students. Chronobiology International, 36(11), 1482–1495. https://doi.org/10.1080/07420528.2019.1652831 Ohayon, M., Wickwire, E. M., Hirshkowitz, M., Albert, S. M., Avidan, A., Daly, F. J. Dauvilliers, Y ., Ferri, R., Fung, C., Gozal, D., Hazen, N., Krystal, A., Lichstein, K., Mallampalli, M., Plazzi, G., Rawd - ing, R., Scheer, F. A., Somers, V ., & Vitiello, M. V . (2017). National Sleep Foundation’s sleep quality recommendations: first report. Sleep Health, 3(1), 6–19. https://doi.org/10.1016/j.sleh.2016.11.006 Okano, K., Kaczmarzyk, J. R., Dave, N., Gabrieli, J. D., & Grossman, J. C. (2019). Sleep quality, dura - tion, and consistency are associated with better academic performance in college students. NPJ Science of Learning, 4(1), 1–5. https://doi.org/10.1038/s41539-019-0055-z Önder, İ., Beşoluk, Ş., İskender, M., Masal, E., & Demirhan, E. (2014). Circadian Preferences, Sleep Quality and Sleep Patterns, Personality, Academic Motivation and Academic Achievement of univer- of univer - sity students. Learning and Individual Differences, 32, 184–192. https://doi.org/10.1016/j.lindif.2014.02.003 Ong, J. C., Huang, J. S., Kuo, T. F ., & Manber, R. (2007). Characteristics of insomniacs with self- reported morning and evening chronotypes. Journal of Clinical Sleep Medicine , 3(3), 289–294. https://doi.org/10.5664/jcsm.26801 Partonen, T. (2015). Chronotype and health outcomes . Current Sleep Medicine Reports, 1, 205–211. https://doi.org/10.1007/s40675-015-0022-z Paul, F ., Schredl, M., & Alpers, G. W . (2015). Nightmares affect the experience of sleep quality but not sleep architecture: an ambulatory polysomnographic study.  Borderline Personality Disorder and Emotion Dysregulation, 2, 3. https://doi.org/10.1186/s40479-014-0023-4 Peters, B. R., Joireman, J., & Ridgway, R. L. (2005). Individual differences in the consideration of future consequences scale correlate with sleep habits, sleep quality, and GPA in university students. Psychological Reports, 96(3), 817–824. https://doi.org/10.2466/pr0.96.3.817-824 Pokhrel, P ., Sussman, S., Sun, P ., Kniazer, V ., & Masagutov, R. (2010). Social self- control, sensation seeking and substance use in samples of US and Russian adolescents. American Journal of Health Behavior, 34(3), 374–384. https://doi.org/10.5993/AJHB.34.3.12 Prat, G., & Adan, A. (2013). Relationships among circadian typology, psychological symptoms, and sensation seeking. Chronobiology International, 30(7), 942–949. https://doi.org/10.3109/07420528.2013.790044 Preckel, F., Lipnevich, A. A., Schneider, S., & Roberts, R. D. (2011). Chronotype, cognitive abilities, and academic achievement: a meta-analytic investigation. Learning and Individual Differences, 21(5), 483–492. https://doi.org/10.1016/j.lindif.2011.07 .003 c e p s Journal 19 Przepiórka, A., Błachnio, A., & Siu, N. Y . F. (2019). The relationships between self-efficacy, self-con - trol, chronotype, procrastination and sleep problems in young adults. Chronobiology International, 36(8), 1025–1035. https://doi.org/10.1080/07420528.2019.1607370 Rahafar, A., Maghsudloo, M., Farhangnia, S., Vollmer, C., & Randler, C. (2016). The role of chrono - type, gender, test anxiety, and conscientiousness in academic achievement of high school students. Chronobiology International, 33(1), 1–9. https://doi.org/10.3109/07420528.2015.1107084 Randjelovic, P ., Stojiljkovic, N., Radulovic, N., Stojanovic, N., & Ilic, I. (2021). Problematic smart - phone use, screen time and chronotype correlations in university students. European Addiction Research, 27(1), 67–74. https://doi.org/10.1159/000506738 Roeser, K., Schlarb, A. A., & Kübler, A. (2013). The Chronotype-Academic Performance Model (CAM): daytime sleepiness and learning motivation link chronotype and school performance in adolescents. Personality and Individual Differences, 54(7), 836–840. https://doi.org/10.1016/j.paid.2012.12.021 Selvi, F. F., Karakaş, S. A., Boysan, M., & Selvi, Y . (2015). Effects of shift work on attention deficit, hyperactivity, and impulsivity, and their relationship with chronotype . Biological Rhythm Research, 46(1), 53–61. https://doi.org/10.1080/09291016.2014.948299 Selvi, Y ., Aydin, A., Atli, A., Boysan, M., Selvi, F ., & Besiroglu, L. (2011). Chronotype differences in suicidal behavior and impulsivity among suicide attempters. Chronobiology International, 28(2), 170–175. https://doi.org/10.3109/07420528.2010.535938 Servidio, R. (2019). Self-control and problematic smartphone use among Italian university students: the mediating role of the fear of missing out and of smartphone use patterns. Current Psychology, 40(8), 4101–4111. https://doi.org/10.1007/s12144-019-00373-z Short, M. A., Gradisar, M., Lack, L. C., & Wright, H. R. (2013). The impact of sleep on adolescent depressed mood, alertness and academic performance. Journal of Adolescence, 36 (6), 1025–1033. https://doi.org/10.1016/j.adolescence.2013.08 Stadler, M., Aust, M., Becker, N., Niepel, C., & Greiff, S. (2016). Choosing between what you want now and what you want most: self-control explains academic achievement beyond cognitive ability. Personality and Individual Differences, 94, 168–172. https://doi.org/10.1016/j.paid.2016.01.029 Steel, P . (2007). The nature of procrastination. Psychological Bulletin, 133, 65–94. https://doi.org/10.1037/0033-2909.133.1.65 Stolarski, M., Ledzińska, M., & Matthews, G. (2013). Morning is tomorrow, evening is today: relation - ships between chronotype and time perspective. Biological Rhythm Research, 44(2), 181–196. https://doi.org/10.1080/09291016.2012.656248 Sun, J., Chen, M., Cai, W ., Wang, Z., Wu, S., Sun, X., & Liu, H. (2019). Chronotype: implications for sleep quality in medical students. Chronobiology International, 38(6), 1–9. https://doi.org/10.1080/07420528.2019.1619181 Taillard, J., Philip, P ., & Bioulac, B. (2002). Morningness/eveningness and the need for sleep. Journal of Sleep Research, 8(4), 291–295. https://doi.org/10.1046/j.1365- 2869.1999.00176.x Tangney, J. P ., Baumeister, R. F., & Boone, A. L. (2004). High self‐control predicts good adjustment, the relationship between chronotype and academic achievement among slovene ... 20 less pathology, better grades, and interpersonal success. Journal of Personality , 72(2), 271–324. https://doi.org/10.1111/j.0022-3506.2004.00263.x Tian, J., Zhao, J., Xu, J., Li, Q., Sun, T., Zhao, C., Gao, R., Zhu, L., Guo, H., Y ang, L., Cao, D., & Zhang, S. (2021). Mobile phone addiction and academic procrastination negatively impact academic achieve - ment among Chinese medical students. Frontiers in Psychology, 12. https://doi.org/10.3389/fpsyg.2021.758303 Tonetti, L., Natale, V ., & Randler, C. (2015). Association between circadian preference and academic achievement: a systematic review and meta-analysis. Chronobiology International, 32(6), 792–801. https://doi.org/10.3109/07420528.2015.1049271 Treven Pišljar, N., Štukovnik, V ., Zager Kocjan, G., & Dolenc-Groselj, L. (2019). Validity and reliability of the Slovene version of the Morningness-Eveningness Questionnaire. Chronobiology International, 36(10), 1409–1417. https://doi.org/10.1080/07420528.2019.1651326 Vitaterna, M. H., Takahashi, J. S., & Turek, F . W . (2001). Overview of circadian rhythms. Alcohol Research & Health, 25(2), 85–93. Vollmer, C., Jankowski, K. S., Díaz-Morales, J. F., Itzek-Greulich, H., Wüst- Ackermann, P ., & Randler, C. (2017). Morningness–eveningness correlates with sleep time, quality, and hygiene in secondary school students: a multilevel analysis. Sleep Medicine, 30, 151–159. https://doi.org/10.1016/j.sleep.2016.09.022 Wang, L. (2014). Body mass index, obesity, and self-control: A comparison of chronotypes. Social Behavior and Personality: An International Journal, 42 (2), 313–320. https://doi.org/10.2224/sbp.2014.42.2.313 Wang, L., & Hu, L. (2015). Are Early Birds More Disciplined? A Social Jet Lag Perspective. Current Psychology, 35(4), 495–505. https://doi.org/10.1007/s12144-015-9322-1 Wittmann, M., Dinich, J., Merrow, M., & Roenneberg, T. (2006). Social jetlag: misalignment of biological and social time. Chronobiology International, 23(1-2), 497–509. https://doi.org/10.1080/07420520500545979 Wong, M. L., Lau, E. Y . Y ., Wan, J. H. Y ., Cheung, S. F ., Hui, C. H., & Mok, D. S. Y . (2013). The interplay between sleep and mood in predicting academic functioning, physical health and psychological health: A longitudinal study. Journal of Psychosomatic Research, 74 (4), 271–277. https://doi.org/10.1016/j.jpsychores.2012.08 Yi, H., Shin, K., & Shin, C. (2006). Development of the Sleep Quality Scale. Journal of Sleep Research, 15(3), 309–316. https://doi.org/10.1111/j.1365-2869.2006.00544.x Zailinawati, A. H., Teng, C. L., Chung, Y . C., Teow, T. L., Lee, P . N., & Jagmohni, K. S. (2009). Daytime sleepiness and sleep quality among Malaysian medical students. The Medical Journal of Malaysia , 64(2), 108–110. Zerbini, G., & Merrow, M. (2017). Time to learn: how chronotype impacts education. PsyCh journal, 6(4), 263–276. https://doi.org/10.1002/pchj.178 Zerbini, G., van der Vinne, V ., Otto, L. K. M., Kantermann, T., Krijnen, W . P ., Roenneberg, T., & Mer - row, M. (2017). Lower school performance in late chronotypes: underlying factors and mechanisms. c e p s Journal 21 Scientific Reports, 7(1). https://doi.org/10.1038/s41598-017-04076-y Zhang, C., Meng, D., Zhu, L., Ma, X., Guo, J., Fu, Y ., Zhao, Y ., Xu, H., & Mu, L. (2023). The effect of trait anxiety on bedtime procrastination: the mediating role of self-control. International Journal of Behavioral Medicine, 30(2), 260–267. https://doi.org/10.1007/s12529-022-10089-3 Zhao, J., Meng, G., Sun, Y ., Xu, Y ., Geng, J., & Han, L. (2021). The relationship between self-control and procrastination based on the self-regulation theory perspective: the moderated mediation model. Current Psychology, 40, 5076–5086. https://doi.org/10.1007/s12144-019-00442-3 Zorjan, S. (2014) . Individual differences and ego depletion effect: the effect of implicit beliefs on self- control. [Master thesis, University of Maribor]. Digital library of University of Maribor. https://dk.um.si/IzpisGradiva.php?lang=slv&id=46567 Biographical note Katarina Maučec , MSc in Psychology, graduated in 2023 at the Fac - ulty of Arts, University of Maribor, Slovenia. Currently, she is working at the Health Promotion Center at the Laško Community Health Centre. She is a member of the European Sleep Research Society. Her research focuses on the psychological dimensions of sleep health, including the impact of sleep on cog - nitive, behavioral, and psychosocial functioning. Vita Štukovnik, PhD, is a clinical psychology specialist and an assis - tant professor of psychology at the Department of Psychology, Faculty of Arts, University of Maribor, Slovenia. Her research interests encompass clinical neu - ropsychology, clinical psychology, and sleep. In her role as a clinical psycholo - gist, she primarily concentrates on the treatment of chronic insomnia and has introduced cognitive-behavioral therapy for insomnia in Slovenia.