Human beings, as diurnal species, generally exhibit activity during the day [1]. Nevertheless, there are notable differences and preferences among individuals regarding their waking and sleeping schedules, as well as their timings for carrying out daily tasks [1]. These variations in personal preferences for functioning at specific times of the day are termed as ‘morningness-eveningness’ or ‘chronotypes’ [2, 3]. In other words, this concept refers to an individual trait related to the preference for operating effectively at different periods of the day [3]. The innate circadian rhythms of individuals significantly influence these preferences [3]. The circadian rhythm, also referred to as the circadian clock or biological clock, not only influences the morningness-eveningness phenomenon but also plays a crucial part in a multitude of physiological and behavioural processes [3, 4]. These include maintaining body temperature stability, regulating hormonal secretions (particularly those linked to sleep, like melatonin), managing sleep-wake cycles, mood and cognitive functions, as well as alertness during the day [3, 4].
Furthermore, the endogenous circadian rhythm inherent in humans interacts with environmental stimuli that contribute to changes in morningness-eveningness [5]. These factors include timing cues provided by the light-dark cycle, mealtimes, social interactions, and social isolation [5]. This interplay corresponds to what is termed as ‘circadian typology’, comprising of three primary chronotypes, namely [5] morning-type (MT), intermediate/neither-type (NT), and evening-type (ET) [1, 2, 5, 6]. People classified as MT typically favour early wake-up and bedtime schedules, experiencing peak alertness and cognitive performance in the morning [7]. Conversely, those characterized as ET tend to have later sleep and wake times, functioning efficiently during late hours [7]. People who are neither MT nor ET are considered as intermediate types [7].
Moreover, individual variations in chronotype preferences are largely influenced by a variety of factors, including one’s individual context [8]. For instance, occupational obligations often push workers towards a morning preference compared to students [8]. Moreover, age significantly alters sleep patterns, with a bedtime of 23:30 possibly indicating an evening chronotype for individuals over 40, whereas the same bedtime could signal a morning preference among students [8]. Therefore, age and work requirements lead to a phase advance in adults over 40, shaping individuals’ chronotypes [8].
Inter-individual variations in circadian rhythms differently affect daily functioning and health outcomes. Research indicates that individuals who are classified as evening-types often report experiencing poorer sleep quality, shorter sleep durations, and episodes of oversleeping [6]. Given that society typically favours morning-types, people with ET chronotype regularly face social jetlag, which detrimentally affects their sleep quality, negatively impacting, in turn, their social functioning [6]. Furthermore, eveningness is also linked to higher incidences of insomnia, behavioural problems [7], and cognitive disruptions [5]. In terms of emotional experience and regulation, people with an ET chronotype tend to report greater mental health challenges and mood disorders [3], lower levels of positive affect, a more pessimistic outlook on life, diminished wellbeing, and reduced life satisfaction [6]. They also commonly experience greater levels of emotional difficulties, attention deficit, and physical complaints [7]. Additionally, the eveningness chronotype is associated with increased alcohol consumption [6], unhealthy dietary habits [5, 9], and lower levels of physical activity [5] compared to MT individuals. On the other hand, individuals with morningness tendencies are often characterized by being more proactive, having reduced inclination towards procrastination, and a more balanced mood throughout the day [10]. Moreover, they typically exhibit higher levels of conscientiousness compared to ET individuals [10]. This high clinical relevance explains the strong need for accurate measures to assess the chronotype construct.
Various questionnaires have been developed to assess chronotypes, including the Munich ChronoType Questionnaire (MCTQ) [11], the Morningness-Eveningness-Stability-Scale improved (MESSi) [12], the Composite Scale of Morningness (CSM) [13], the Preferences Scale (PS) [14], and the Morningness-Eveningness Questionnaire (MEQ) [15]. Among these measures, the MEQ stands out as one of the most widely used self-report chronotype scale (for review, see [16]). The MEQ is a 19-item scale developed by Horne and Ostberg [15]. It evaluates sleep and wake times, preferred periods of activity, and perceived levels of alertness [16]. The scale categorizes chronotypes into five groups based on individuals’ results, with the scores ranging from 16 to 86: ‘definite evening type, moderate evening type, intermediate type, moderate morning type, and definite morning type’ [15, 16]. Higher scores on the MEQ are indicative of the morningness chronotype while lower scores reflect the eveningness chronotype [17]. The validity of the MEQ was demonstrated in different age groups and various populations worldwide, using both subjective and objective measures [16]. However, the original 19-item MEQ has been criticized for its length and can be time-consuming to complete [18]. In addition, there have been concerns around the factor structure of the MEQ, with some authors suggesting that the significant portions of the variance may be explained by only few items. For example, Zickar et al. [19] stated that MT items seem to provide the best discrimination, whereas Adan and Almirall [20] proposed that four MEQ items showed weak discriminatory power. To address these issues, Adan and Almirall [21] developed a simplified, reduced 5-item version, the rMEQ, which is easier for respondents to complete. It includes items 1, 7, 10, 18 and 19 from the original MEQ. These 5 items focus on morning-oriented activity, making the rMEQ a more accurate indicator of MT chronotype [22]. The reliable psychometric characteristics of the rMEQ as well as its concise format have made it a popular measure for the assessment of chronotypes in numerous countries, namely Saudi Arabia [23], France [24, 25], China [26], USA [27], Italy [18], Germany [28]. The rMEQ demonstrates good psychometric characteristics, adequate construct validity, aligns well with the MEQ in terms of convergent validity, and it has good test-retest reliability [22]. The total score on the rMEQ can range from 4 to 24 [21]. Regarding cutoff scores, the three chronotype groups are defined as follows: a score below 12 indicates an ET, scores from 12 to 17 suggest an intermediate chronotype, and scores above 17 indicate an MT [22]. Studies have found that the rMEQ is better able to categorize chronotypes compared to the original 19-item MEQ [29].
The present study
This study investigates the psychometric properties of the Arabic version of the rMEQ in a sample of Arabic-speaking young adults from Lebanon. The objective is to determine the factor structure of the Arabic rMEQ and provide evidence supporting the scale's cross-cultural validity. The rMEQ chosen because it has been validated in multiple cultures and has consistently shown reliability in evaluating chronotypes across various groups [30–32]. Moreover, the examination of psychometric properties of the scale before it can be used among Arabic-speaking individuals is important to ensure that the morningness-eveningness phenomenon exhibits the same patterns across different cultures [33]. Some studies indicate that levels of morningness and eveningness can vary among different cultural groups [34]. In Lebanon, for instance, the chronotypes of young adults were seen to be majorly of the intermediate type, with 7.3% being MT and 24.5% being ET [35]. This is similar to the findings in Saudi young adults with the intermediate type being most common, followed by the ET chronotype and the MT being the least common [23]. On the contrary, studies conducted in European countries, namely Germany [36] and Czech Republic [37], demonstrated a greater percentage of MT compared to ET, with the intermediate type being the most common. Moreover, an environmental hypothesis posits that people living near the Earth's equator are generally more morning-oriented compared to those residing at higher latitudes [34]. A study in Turkey found that individuals from the eastern and southern regions of the country tend to exhibit morningness, whereas those from the western and northern regions are more evening-oriented [38]. This suggests that climate and latitude can impact a person's chronotype [34, 38]. Given that Lebanon is a Middle Eastern country located in the Levant, in the eastern Mediterranean region [39], its unique geographical position provides an appropriate context to further confirm the original factor structure of the rMEQ and understand whether chronotypes have similar configuration across cultures and populations.
The primary objective of this study was to evaluate the psychometric properties of the Arabic version of the rMEQ in Lebanese young adults. Specifically, we aimed to determine the factor structure of the Arabic rMEQ and assess its reliability and validity in this cultural context. We hypothesize that the original one-factor structure of the rMEQ will be confirmed in this population. Furthermore, we anticipate that the scale will show good internal consistency reliability, as well as adequate patterns of correlations with measures of sleep quality and depression/anxiety symptoms, thus attesting its concurrent validity.