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

Randler, Christoph; Rahafar, Arash

doi:10.1038/srep39976

Cited by 56 publications

(26 citation statements)

References 25 publications

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“…Other regions like the South, present higher daylight periods in the Summer and the opposite occurs during the Winter. Changes according to seasons may affect sleep outcomes as sleep duration and schedule sleep regulation 34 . Another explanation is that in Brazil, the daylight-saving time during Summer is only adopted in some regions (South, Southeast and Central).…”

Section: Discussionmentioning

confidence: 99%

Sleep disturbances and daytime fatigue: data from the Brazilian National Health Survey, 2013

et al. 2019

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This study aims to describe the prevalence of sleep disturbances and daytime fatigue and their association with socio-demographic and behavioral factors. Data from the Brazilian National Health Survey conducted in 2013 with 60,202 adults (≥ 18 years old) were used. The outcomes evaluated were self-reported sleep disturbances and daytime fatigue in the last two weeks. Sleep disturbance was defined as the presence of difficulty to fall asleep, frequently waking up during the night or sleeping more than usual; daytime fatigue was defined as the presence of not feeling rested and motivated during the day, feeling tired and lacking energy. Sociodemographic, lifestyle and chronic health aspects were explored as exposures for both outcomes. Prevalence of sleep disturbances and daytime fatigue were 14.9% (14.4-15.4) and 11.9% (11.4-12.3), respectively. Both outcomes were more common in women, older people, people with no formal education, smokers and among physically inactive individuals. The association with education was inverse (the highest the level of education the lower the prevalence ratio - PR - of sleep disturbances and daytime fatigue; adjusted p-value for trend < 0.001). Prevalence of sleep disturbances combined with daytime fatigue was 6.7% (6.4-7.1) and was about 6 times higher among those with three or more chronic health disturbances (PR = 6.2; 95%CI: 5.3-7.2). Strategies to decrease the prevalence of sleep disturbances and daytime fatigue should be encouraged and focused on chronically ill individuals that share other modifiable risk factors.

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Section: Discussionmentioning

confidence: 99%

Sleep disturbances and daytime fatigue: data from the Brazilian National Health Survey, 2013

et al. 2019

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“…Therefore, it is reasonable to assume that regular daytime naps to counteract accumulating sleep debt would alleviate SJL symptoms. Currently, most studies on SJL have been performed in Western countries [10,11]. It is difficult to investigate the relationship between daytime naps and SJL in these countries, since typically the general public rarely takes naps.…”

Section: Introductionmentioning

confidence: 99%

Social Jetlag and Chronotypes in the Chinese Population: Analysis of Data Recorded by Wearable Devices

2019

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Background Chronotype is the propensity for a person to sleep at a particular time during 24 hours. It is largely regulated by the circadian clock but constrained by work obligations to a specific sleep schedule. The discrepancy between biological and social time can be described as social jetlag (SJL), which is highly prevalent in modern society and associated with health problems. SJL and chronotypes have been widely studied in Western countries but have never been described in China. Objective We characterized the chronotypes and SJL in mainland China objectively by analyzing a database of Chinese sleep-wake pattern recorded by up-to-date wearable devices. Methods We analyzed 71,176 anonymous Chinese people who were continuously recorded by wearable devices for at least one week between April and July in 2017. Chronotypes were assessed (N=49,573) by the adjusted mid-point of sleep on free days (MSFsc). Early, intermediate, and late chronotypes were defined by arbitrary cut-offs of MSFsc <3 hours, between 3-5 hours, and >5 hours. In all subjects, SJL was calculated as the difference between mid-points of sleep on free days and work days. The correlations between SJL and age/body mass index/MSFsc were assessed by Pearson correlation. Random forest was used to characterize which factors (ie, age, body mass index, sex, nocturnal and daytime sleep durations, and exercise) mostly contribute to SJL and MSFsc. Results The mean total sleep duration of this Chinese sample is about 7 hours, with females sleeping on average 17 minutes longer than males. People taking longer naps sleep less during the night, but they have longer total 24-hour sleep durations. MSFsc follows a normal distribution, and the percentages of early, intermediate, and late chronotypes are approximately 26.76% (13,266/49,573), 58.59% (29,045/49,573), and 14.64% (7257/49,573). Adolescents are later types compared to adults. Age is the most important predictor of MSFsc suggested by our random forest model (relative feature importance: 0.772). No gender differences are found in chronotypes. We found that SJL follows a normal distribution and 17.07% (12,151/71,176) of Chinese have SJL longer than 1 hour. Nearly a third (22,442/71,176, 31.53%) of Chinese have SJL<0. The results showed that 53.72% (7127/13,266), 25.46% (7396/29,045), and 12.71% (922/7257) of the early, intermediate, and late chronotypes have SJL<0, respectively. SJL correlates with MSFsc (r=0.54, P <.001) but not with body mass index (r=0.004, P =.30). Random forest model suggests that age, nocturnal sleep, and daytime nap durations are the features contributing to SJL (their relative feature importance is 0.441, 0.349, and 0.204, respectively). Conclusions Our data suggest a higher proportion of early compared to late chronotypes in Chinese. Chinese have less SJL than the results reported in European pop...

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“…There are biological factors (specific genes3), individual factors (e.g., age, sex1) and environmental factors (e.g., changes of light and dark, latitudinal influence4). In addition, social factors also influence chronotype (e.g., time schedules in school, shift work, lifestyle5).…”

mentioning

confidence: 99%

From Lark to Owl: developmental changes in morningness-eveningness from new-borns to early adulthood

Randler

Faßl

Kalb

2017

Sci Rep

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177

125

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Morningness-eveningness or chronotype changes significantly throughout the life span. This has been reported for the transition during adolescence in some studies, and to a lesser extent in early adulthood. Primary and pre-school children have been under investigation in fewer studies. This is the first comprehensive study covering the age range from very young children until early adulthood (0–30 years) based on the same measurement instrument. Here, we show that the turn towards eveningness starts at an early age in German children. Based on 26,214 cross-sectional data, we further show that at the end of adolescence, morningness-eveningness does not significantly change during early adulthood. Sex differences arise during puberty and remain until 30 years. The breaking point for the turn towards morningness is 15.7 years in girls and 17.2 boys. At the age of 0–1 years, there are about 70% morning types, and about 1% evening types, while at the age of 16 years, only 5% are morning types and 19% are evening types.

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

Cited by 56 publications

References 25 publications

Sleep disturbances and daytime fatigue: data from the Brazilian National Health Survey, 2013

Sleep disturbances and daytime fatigue: data from the Brazilian National Health Survey, 2013

Social Jetlag and Chronotypes in the Chinese Population: Analysis of Data Recorded by Wearable Devices

From Lark to Owl: developmental changes in morningness-eveningness from new-borns to early adulthood

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