Geographic latitude and sleep duration: A population-based survey from the Tropic of Capricorn to the Antarctic Circle

The impact of latitude on sleep duration remains virtually unexplored, even though latitude exerts profound influences on daylight duration. Using Chile as a one-country model, we explored on the potential associations between sleep duration and latitude. Based on the 2nd Chilean Health Survey, we i...

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Bibliographic Details
Published in:Chronobiology international 2017-03, Vol.34 (3), p.373-381
Main Authors: Brockmann, Pablo E., Gozal, David, Villarroel, Luis, Damiani, Felipe, Nuñez, Felipe, Cajochen, Christian
Format: Article
Language:English
Subjects:
Adult
Antarctic Regions
Circadian
Circadian Rhythm - physiology
Environment
Female
geography
Humans
insomnia
Logistic Models
Male
Middle Aged
Photoperiod
Seasons
Sleep - physiology
sleep hours
sleepiness
Surveys and Questionnaires
Time Factors
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Summary:The impact of latitude on sleep duration remains virtually unexplored, even though latitude exerts profound influences on daylight duration. Using Chile as a one-country model, we explored on the potential associations between sleep duration and latitude. Based on the 2nd Chilean Health Survey, we identified reported sleep data during spring of people living from north to south in Chilean cities, located between 18°29ʹS to 53°18ʹS (4329 km distance at same longitude). A total of n = 2493 participants were included (mean age 45.3 ± 18.4 years, 41.8% males). Mean sleep duration on workdays and weekends was 7.42 ± 1.71 h, and 7.91 ± 2.13 h, respectively, ranging from 7.91 ± 1.92 h in the north to 8.33 ± 1.89 h in the south, such that more northern latitudes (i.e., 18°29ʹS to 39°50ʹS) slept less compared to more southern latitudes (i.e., 51°43ʹS-53°18ʹ), even after controlling for age, gender, and socioeconomic status. In the logistic regression models, men residing at northern latitudes exhibited an odds ratio of 3.348 [95% CI: 1.905-5.882; p < 0.0001] for having shorter sleep on weekends than their southern counterparts. Latitude appears to strongly affect reported sleep patterns, leading to longer sleep duration with increasing latitude, particularly in men during weekends. Whether environmental factors such as photoperiod are causally involved in theses associations needs to be elucidated in future studies.
ISSN:0742-0528
1525-6073
DOI:10.1080/07420528.2016.1277735