https://doi.org/10.1140/epjs/s11734-026-02221-1
Regular Article
Relationships of country’s sleep times with its thermal environment: preliminary evidence
1
Sheba Medical Center, Tel Aviv University, Tel Hashomer, 52621, Ramat Gan, Israel
2
Independent Research Group, Biomedical Systems Math-Modeling”, 12489, Berlin, Germany
a
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Received:
23
December
2025
Accepted:
17
February
2026
Published online:
28
February
2026
Abstract
The thermal environment seems to be one of the most important factors influencing human sleep. The negative association between sleep and high air temperature and humidity has been previously uncovered by within-person analysis. We tested whether the differences between countries in weekday and weekend sleep timing and duration could at least partly resemble the differences revealed by within-person analysis of the effects of heat and humid heat on sleep. Moreover, we applied a model of the processes of sleep–wake regulation to link these differences to the differences in the parameters of these processes. The set of 2364 samples with reported bed- and risetimes on weekdays and weekends was divided into three subsets representing countries with colder, warmer and drier, and warmer and wetter climates (n = 786, 703, and 875 samples, respectively). Compared to people living in counties with colder climates, people living in counties with warmer or wetter climates spend approximately a quarter of hour less in bed. The contribution of delayed bedtimes to this difference was larger in warmer than colder climate, whereas advanced risetimes contributed larger to this difference between drier and wetter climate. The results of model-based simulations showed that these relationships can be explained by influence of the thermal environment on the processes of sleep–wake regulation underlying the reported sleep times.
Key words: Sleep duration / Sleep-wake regulating processes / Hot temperature / Humid heat
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjs/s11734-026-02221-1.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
