Adaptation of the Morningness-Eveningness Stability Scale improved (MESSi) into Turkish.

Morningness-eveningness is an individual difference that is related with various traits such as behavioral problems, personality, and health. The aim of the current study is to adopt the Morningness-Eveningness Stability Scale improved (MESSi) which is a novel assessment tool that consists of subscales of morning affect (MA), eveningness (EV), and distinctness (DI) into Turkish. Concurrent validity of the MESSi along with Big five inventory (BIG-5), Subjective alertness level, Pittsburg Sleep Quality Index (PSQI), Positive and Negative Affect Schedule (PANAS) were analyzed. The scale was administered to 1,076 high school and university students aged 14-47 years (M = 19.49, SD = 3.53). The explanatory factor analysis (EFA) and confirmatory factor analysis (CFA) revealed the three-factor structure of MESSi. According to the concurrent validity result of the MESSi with BIG-5, conscientiousness was found to correlate positively with MA and negatively with EV. Also, extraversion showed a negative correlation with DI and positive correlation with MA. Furthermore, the subjective alertness rating results showed that MA was positively related to alertness in the morning hours and negatively in the evening hours. Also, sleep quality-related results showed that EV and DI are positively related to total PSQI scores and negatively related to MA. In addition, concerning positive affect (PA) and negative affect (NA), MA was positively related with PA and negatively with NA, while DI was negatively related with PA and positively with NA. In overall, MESSi is a valid and reliable instrument and can be used in Turkish students.

Morningness-eveningness and the environment hypothesis - A cross-cultural comparison of Turkish and German adolescents.

Individuals differ in morningness-eveningness, which is their preferred time for intellectual and physical activities. Although it is a basic human trait, cross-cultural comparisons are scarce but interesting because they help to determine the influence of exogenous factors, such as ambient temperature, climate and photoperiod. We here compare a large sample of German and Turkish adolescents (N = 26 465) by using the Composite Scale of Morningness and the Morning Affect Factor. First, we show that the Morning Affect Factor and Morningness scores are equivalent in both countries and we report country differences with Turkish adolescents scoring higher on morningness (F1,26 038 = 1293.313, p < 0.001) and in the morning affect (F1,26 038 = 133.833, p < 0.001). This fits into the environment hypothesis suggesting that populations near the equator should be more morning oriented. Meanwhile, gender differences were small and adolescents showed a lower morningness and a lower morning affect with increasing age.