UBC Undergraduate Research

Chronotype’s Effects on Health Across Countries Shi, Lianjie; Heine, Steven J.


Chronotype refers to the time that people typically sleep during a 24-hour period. People with earlier chronotypes usually get up earlier and are more active in the morning than those with later chronotypes. Chronotype has been found to vary across countries, and research finds that within countries a later chronotype is correlated with worse health outcomes. This study examines chronotype’s effect on people’s physical and mental health levels across different countries. We recruited 5128 participants from 20 countries over six continents, with approximately 250 participants in each country. Participants completed the survey in a two-week window before and after the autumn equinox, reporting their chronotypes, mental health levels, physical health levels, and depression levels. We used multilevel modeling to study the effect of chronotype on people’s health outcomes within and between countries. We found that within countries, people with chronotypes that are later than the corresponding country’s average tend to have lower physical and mental health outcomes. However, the analysis of between-country effects did not show any relationship between chronotype and people’s health outcomes. Our study’s findings highlight the importance of cultural fit in the relationship between chronotype and health level, demonstrating that people’s chronotypes are most relevant for predicting people’s health in comparison with their own countries’ averages.

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