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

Horzum, Mehmet Barış; Randler, Christoph; Masal, Ercan; Beşoluk, Şenol; Önder, İsmail; Vollmer, Christian

doi:10.3109/07420528.2015.1041598

Cited by 19 publications

(9 citation statements)

References 35 publications

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“…This assumption leads us to propose that the chronotype is a mutable intrinsic property and not a fixed characteristic of the human circadian system; instead, it should be, at least in part, a flexible outcome resulting from the light/dark signaling that acts on an individual’s internal timing, which is regulated by genetic and ontogenetic factors 28 . Furthermore, our results are in line with the previously proposed environment hypothesis 16, 29 , since we consider as tied to latitude both temperature (that increased towards equator and leads to morningness 30 and amplitude of sunset and sunrise (increases towards the poles and leads to eveningness 10 .…”

Section: Discussionsupporting

confidence: 92%

Latitudinal cline of chronotype

Leocádio-Miguel

Louzada

Duarte

et al. 2017

Sci Rep

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The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth’s axis in relation to the plane of the earth’s orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability. In the present study, we tested the hypothesis that latitude is associated to the regulation of circadian rhythm in humans. We have studied chronotype profiles across latitudinal cline from around 0° to 32° South in Brazil in a sample of 12,884 volunteers living in the same time zone. The analysis of the results revealed that humans are sensitive to the different sunlight signals tied to differences in latitude, resulting in a morning to evening latitudinal cline of chronotypes towards higher latitudes.

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Section: Discussionsupporting

confidence: 92%

Latitudinal cline of chronotype

Leocádio-Miguel

Louzada

Duarte

et al. 2017

Sci Rep

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“…on 6 countries. Thus, the study confirms the environment hypothesis6 around the globe. Higher latitudes are associated with higher eveningness.…”

Section: Discussionsupporting

confidence: 87%

“…The light-dark cycle (as manifested in sunrise, sunset and photoperiod) as well as other environmental cues (e.g., temperature) have been proposed to influence M/E1 and this was explicated as the “environment hypothesis”6. Latitude, as a surrogate was therefore used as an influential factor in some studies, because latitude is grossly correlated with both, average temperature and photoperiod.…”

mentioning

confidence: 99%

Latitude affects Morningness-Eveningness: evidence for the environment hypothesis based on a systematic review

Randler

Rahafar

2017

Sci Rep

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Morningness-eveningness (M/E) is an individual trait related to a person’s sleep-wake cycle and preference for morning or evening hours. The “environment hypothesis” suggests that M/E is dependent on environmental factors, such as latitude, mean average temperature and photoperiod. We here analyzed a large number of datasets to assess this effect based on a systematic review. Data were from a total of 87 datasets and 35,589 individuals based on 28 countries. Partial correlations correcting for age revealed significant relationships between M/E and latitude, mean yearly temperature, photoperiod and sunset. Evening orientation was related to higher latitude, longer days and later sunset. Morning orientation was related to higher average temperatures. Percentage of females and sunrise time had no significant influence. These variables (sunset, temperature, photoperiod) were then input in a general linear model. The full model showed an influence of age and of sunset on CSM scores, but not of photoperiod and average temperature. Sunset, therefore, seems to be the most important statistical predictor for the observed latitudinal gradient.

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“…The total score varies from a minimum of 13 to a maximum of 55 with high scores reflecting high morningness. The scale has been used in many different countries and shows good psychometric properties and convergent validity (Di Milia, Adan, Natale, & Randler, 2013; Horzum et al., 2015). Cronbach’s α coefficient of the CSM scale was 0.84 in the SAPS study and 0.88 in the SAS.…”

Section: Methodsmentioning

confidence: 99%

Smartphone addiction proneness in relation to sleep and morningness–eveningness in German adolescents

et al. 2016

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BackgroundMobile phones are an important part of adolescents’ life. In this study, the relationships among smartphone addiction, age, gender, and chronotype of German adolescents were examined.Materials and methodsTwo studies focused on two different measures of smartphone addiction. The Smartphone Addiction Proneness Scale (SAPS) was applied to 342 younger adolescents (13.39 ± 1.77; 176 boys, 165 girls, and 1 not indicated) in Study 1 and the Smartphone Addiction Scale was applied to 208 older adolescents (17.07 ± 4.28; 146 girls and 62 boys) in Study 2, both samples in southwest Germany. In addition, a demographic questionnaire and the Composite Scale of Morningness (CSM) and sleep measures were implemented.ResultsThe most remarkable result of this study was that morningness–eveningness (as measured by CSM scores) is an important predictor for smartphone addiction; even stronger than sleep duration. Evening oriented adolescents scored higher on both smartphone addiction scales. In addition, gender is an important predictor for smartphone addiction and girls are more prone to become addicted. In addition, while sleep duration on weekdays negatively predicted SAPS, age, sleep duration on weekends, and midpoint of sleep on weekdays and weekends did not predicted smartphone addiction in both scales. The analysis of covariance revealed statistically significant effects of the covariates gender and age in both studies, as well as the main effect of chronotype. According to the t-test results, girls had higher scores than boys in smartphone addiction.ConclusionEvening types and girls are more prone to become smartphone addicted.

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

Cited by 19 publications

References 35 publications

Latitudinal cline of chronotype

Latitudinal cline of chronotype

Latitude affects Morningness-Eveningness: evidence for the environment hypothesis based on a systematic review

Smartphone addiction proneness in relation to sleep and morningness–eveningness in German adolescents

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