Relationship of Lifestyle Habits with Sleep Quality among Japanese in Their 20s

The purpose of this study was to analyze the effects of lifestyle on sleep quality in young Japanese adults. A cross-sectional study was conducted on the web. We analyzed 637 eligible subjects (316 men and 321 women) aged 20 - 29 years. Information on diet and individual lifestyle characteristics, including sleep quality, which was assessed using the Pittsburgh Sleep Quality Index Japanese version (PSQI-J). Results were obtained by participants completing an online questionnaire. The participants were divided into two groups based on whether they were students (“student group”) or not (“not student group”). The participants with a PSQI-J global score of 6 or higher were evaluated as low-sleep-quality. Logistic regression analyses were performed to evaluate associations of lifestyle habits with low-sleep-quality. Logistic regression analyses were applied for “student group” and “not student group”. The results showed that days of eating out at dinner (OR: 1.11, CI: 1.00 - 1.22) and skipping dinner (OR: 1.21, CI: 1.05 - 1.42) were significant and independent predictors for low-sleep-quality among the “not student group”. There were no significant and independent predictors for low-sleep-quality among “student group”. Our results suggested that excessive intake by eating out and deficient intake by skipping dinner might lead to a high PSQI-J score. It is necessary for young people to receive education on the importance of cooking their own meals for traditional and daytime eating. The implication of this study lies in the fact that we have analyzed the effects of lifestyle habits on quality of sleep.

Effect of Eating out on Quality and Quantity of Sleep among Japanese in Their 20s

The purpose of this study was to analyze the effects of eating out or skipping meals on the quality or quantity of sleep in young Japanese adults. We analyzed 584 eligible subjects (283 men and 301 women) aged 20 - 29 years. Information on diet and individual lifestyle characteristics, including sleep quality, which was assessed by the Pittsburgh Sleep Quality Index Japanese version (PSQI-J), were obtained by participants completing an online questionnaire. Kendall’s tau coefficient was used to measure the ordinal association between diet and sleep quality. The Mann-Whitney U test was performed to evaluate differences in sleep quality by frequency of eating out and frequency of skipping meals. The results revealed a significant difference in sleep duration and PSQI-J score between people who eat out >2 times a week (“high restaurants group”) and those who do not (“low restaurants group”). Furthermore, whereas the mean sleep duration in the “high restaurants group” was 6.59 hours, the mean sleep duration in the “low restaurants group” was 6.90 hours (p = 0.007). The PSQI-J score was significantly higher in the “high restaurants group” than in the “low restaurants group” (4.91 versus 4.37, p = 0.006). Significant differences were also evident in the test’s component scores: C2, C3, and C7. No significant difference was found in sleep duration and PSQI-J score between the groups in terms of frequency of skipping meals (breakfast, lunch, and dinner). Our results suggested that excessive intake by eating out more than twice a week may lead to short sleep duration and high PSQI-J score.