Circadian preference in Italy and India: A comparative study in young adults

The present study aimed to investigate the possible role played by environmental temperature in modulating circadian preference, collecting data in Italy and India. We chose these countries because of extremely different mean maximum temperatures. The reduced version of the Morningness–Eveningness Questionnaire (MEQr) was administered to 1462 young adults (479 males and 983 females; 952 Italians and 510 Indians), ranging in age between 18 and 28 years. Considering morningness–eveningness preference as a continuum, in the whole sample females gained higher MEQr scores than males, indicating a preference towards morningness. Indians reported significantly higher MEQr scores than Italians. Moreover Italian females showed significantly higher MEQr scores than Italian males, while this difference was not observed between Indian females and males. These results have been confirmed also when chronotypes as categories were considered. On the whole our results highlight a significantly different distribution of circadian preference in the two countries, with higher prevalence of morningness in India and eveningness in Italy. The present findings are discussed in relation to the higher environmental temperatures in India in comparison to Italy.