Objectives Our study examines differences in eating behaviour between day workers and rotating shift workers, and considers whether diurnal preference could explain the differences. Methods Japanese female nurses were studied (39 day workers and 123 rotating shift workers, aged 21–63 years) using self-administered questionnaires. The questionnaires assessed eating behaviours, diurnal preference and demographic characteristics. The questionnaire in the Guidelines for the management of obesity disease issued by the Japan Society for the Study of Obesity was used to obtain scores for the levels of obesity-related eating behaviours, including cognition of constitution, motivation for eating, eating as a diversion, feeling of satiety, eating style, meal contents and temporal eating patterns. The Japanese version of the Morningness–Eveningness (ME) questionnaire was used to measure self-rated preference for the degree to which people prefer to be active in the morning or the evening (ME). Results The scores for meal contents and temporal eating patterns in rotating shift workers were significantly higher than those in day workers. The ME score of rotating shift workers was significantly lower, indicating greater eveningness/less morningness among rotating shift workers. Multivariate linear regression revealed that the ME score was significantly negatively associated with temporal eating patterns and showed a negative association with the score for meal contents at a trend level, while current work shift was not significantly correlated with the scores. Conclusions These results suggest that eating behaviours for rotating shift workers are associated with a more unbalanced diet and abnormal temporal eating patterns and that the associations may be explained by diurnal preference rather than by rotating shift work.

Rotating shift workers are associated with imbalanced dietary intakes. Rotating shift workers and dietary intakes in adults who do not engage in night work have also been shown to be associated with chronotype. However, no studies have examined associations between morningness-eveningness (i.e., the degree to which people prefer to be active in the morning or the evening), rotating shift work and dietary intakes. Therefore, our first purpose was to elucidate the association between morningness-eveningness and habitual food group intakes in rotating shift workers. The second purpose was to elucidate the association of morningness-eveningness and rotating shift work with food group intakes, considering habitual sleep durations. Japanese nurses (1095 day workers and 1464 rotating shift workers) were studied using a self-administered questionnaire. The questionnaire covered habitual dietary intakes, morningness-eveningness and demographic characteristics of the participants. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure self-rated morningness-eveningness. Dietary intakes over the previous 1 month were evaluated using a semi-quantitative food frequency questionnaire. Intakes of pulses, green/yellow vegetables, white vegetables, fruits, algae, eggs, confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) associated with the MEQ score in rotating shift workers. Among these food groups, intakes of green/yellow vegetables, white vegetables, fruits and algae were significantly (p < 0.05) lower in rotating shift workers than in day workers, and intakes of confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) higher in rotating shift workers than in day workers. Intakes of these food groups were also significantly (p < 0.05) associated with the MEQ score in day workers. In addition, the MEQ score was significantly (p < 0.05) lower in rotating shift workers than in day workers, indicating greater eveningness among rotating shift workers. Multivariate linear regression revealed that the MEQ scores were significantly (p < 0.05) associated with intakes of these food groups, while rotating shift work was associated only with confectioneries/savory snacks. These results suggest that morningness-eveningness is associated with unbalanced dietary intakes in rotating shift workers as well as day workers, which may partially explain associations between rotating shift work and unfavorable dietary intakes. These findings have important implications for the development of novel strategies for preventing poor health caused by imbalanced dietary intakes in rotating shift workers.

Background: In Japan, a new type of foods with health claims, called Foods with Function Claims (FFC), was introduced in April 2015 in order to make more products available that are clearly labeled with certain health functions. Regarding substantiating product effectiveness, scientific evidence for the proposed function claims must be explained by systematic reviews (SRs), but the quality of SRs was not clear. The objectives of this review were to assess the quality of SRs based on the FFC registered on the Consumer Affairs Agency (CAA) website in Japan, and to determine whether the CAA’s verification report in 2016 was associated with improvement in the quality of SRs. Methods: We evaluated the reporting quality of each SR by the AMSTAR checklist on methodological quality. We searched the database from 1 April to 31 October 2015 as the before-SR and from 1 July 2017 to 31 January 2018 as the after-SR. Results: Among the 104 SRs reviewed, 96 final products were included: 51 (53.1%) were supplements, 42 (43.8%) were processed foods without supplements, and 3 (3.1%) were fresh foods. Of the 104 SRs, 92 (88.5%) were qualitative reviews (i.e., without meta-analysis) and 12 (11.5%) performed a meta-analysis. The average quality score of before-SRs and after-SRs was 6.2 ± 1.8 and 5.0 ± 1.9, respectively, a statistically significant decrease (p < 0.001). Conclusion: Overall, the methodology and reporting quality of after-SRs based on the FFC were poorer than those of before-SRs. In particular, there were very poor descriptions and/or implementations of study selection and data extraction, search strategy, evaluation methods for risk of bias, assessment of publication bias, and formulating conclusions based on methodological rigor and scientific quality of the included studies.

This study aimed to investigate the associations between objectively measured sleep timing and habitual dietary intake among university students. We hypothesized that a later chronotype and larger social jetlag (SJL) are associated with an undesirable dietary intake. The 82 healthy university students included in this study were asked to undertake a seven-day wrist activity recording. All the participants also completed a self-administered questionnaire during the recording period, including questions on demographic characteristics and habitual dietary intakes. Dietary intake and the score for adherence to the Japanese Food Guide Spinning Top (food guide score) over the previous month were evaluated using a self-reported diet history questionnaire. Nocturnal sleep timing and total sleep time for each night were estimated using the recorded wrist activity. Chronotype was calculated as weekend (WE) mid-sleep time corrected for catch-up sleep on weekdays (WDs). SJL was calculated by subtracting WD mid-sleep time from WE mid-sleep time. Multivariable linear regression showed that a later chronotype was significantly (P < .05) associated with a lower consumption of eggs, greater consumption of grains, and lower food guide score. Multivariable linear regression also showed significant (P < .05) associations of a larger value in SJL with a lower total energy intake, lower consumption of grains, and greater consumption of sugar and confectioneries. The results suggest that chronotype and SJL may be differently associated with undesirable dietary intake in young adults. These findings have important implications for developing novel strategies, focusing on sleep timing, for improving dietary intakes and preventing lifestyle-related diseases.

Although it has been shown that specific foods and nutrients are associated with sleep quality, few studies have examined the association of dietary variety and appetite with sleep quality in older adults.

This study aimed to elucidate the association between adherence to the Japanese Food Guide Spinning Top (Food Guide score) and sleep quality in Japanese college students. We conducted a cross-sectional study of 175 Japanese college students aged 19–22 years in the eastern part of Gunma Prefecture to examine the association between the Food Guide score and sleep quality. A self-administered diet history questionnaire and the Pittsburgh Sleep Quality Index were used to assess habitual dietary intake and sleep quality, respectively. In the fully adjusted model, the odds ratios for poor sleep quality in the middle and highest tertile categories of the Food Guide score were 0.50 (95% confidence interval, 0.18–1.37) and 0.30 (95% confidence interval, 0.11–0.84), respectively, compared with those in the lowest tertile category (p for trend = 0.033). A well-balanced diet may be associated with good sleep quality in Japanese college students.