Seasonality in mood and behaviours of Japanese residents in high-latitude regions: transnational cross-sectional study.

Yumiko Kurata,Shinobu Nomura,Shuhei Izawa

doi:10.1186/s13030-016-0084-2

Yumiko Kurata, Shinobu Nomura + Show 1 more

Open Access

https://doi.org/10.1186/s13030-016-0084-2

Copy DOI

Abstract

BackgroundDaylight hours in high-latitude regions tend to be longer than those in Japan in summer, and shorter than those in Japan in winter. For example, daylight hours in London in winter are one-third those of Tokyo. Therefore, this study investigated and compared seasonal changes in mood and behaviours of Japanese individuals living in and outside Japan.MethodsSurveys were conducted with Japanese residents in summer and winter in the UK (n = 106), Nordic countries (n = 40), Southeast Asia (n = 50), and Japan (n = 96). First, summer and winter General Health Questionnaire–28 (GHQ28) scores of each regional group were analysed. Subsequently, month-wise differences in mood and behaviours were compared across the four geographical regions.ResultsSummer and winter GHQ28 scores of participants living in the UK and Nordic countries differed significantly, while no seasonal differences were observed for residents in Japan and Southeast Asia. Further, in the UK and Nordic countries, summer was associated with better mood and more activity, while winter was linked to lowered mood and reduced activity.ConclusionThe results indicate that Japanese living in the UK and Nordic countries (high-latitude regions) experience seasonal fluctuations in depressive symptoms that may be linked to drastic seasonal environmental changes. Observed over a 12-month period, their mood and behaviour declined in winter and improved in summer. Therefore, considering the prevalence of overseas stressors that differ from those in their home country, it is necessary to investigate the effectiveness of support systems that help migrants adapt to seasonal changes in high-latitude regions.

Highlights

Daylight hours in high-latitude regions tend to be longer than those in Japan in summer, and shorter than those in Japan in winter
No significant seasonal differences in total or subscale scores among participants living in Japan and Southeast Asia were observed
3.72, p < .01) and Nordic countries (t = 2.30, p < .05) (Table 3). This suggests that seasonal changes affected the mental health of Japanese migrants in high-latitude regions differently than they did for Japanese living in Japan or low-latitude regions

Summary

Introduction

Daylight hours in high-latitude regions tend to be longer than those in Japan in summer, and shorter than those in Japan in winter. This study investigated and compared seasonal changes in mood and behaviours of Japanese individuals living in and outside Japan. According to the annual report by the Ministry of Foreign Affairs of Japan, both the number of Japanese people living overseas on a long-term basis, and the prevalence of mental disorders, mental illness, and suicide of such people have increased [1, 2]. 300,000 Japanese individuals live in areas that lie above latitude 50°N and experience. Among Asian, White, and Black individuals in the UK, Asians were the only ethnic group that showed significant seasonal variations in depression, with a greater number of depressive episodes in winter [9]. Gender and ethnicity may be major risk factors for low mood in winter [9]

Methods

Results

Discussion

Conclusion