Sleep curtailment in healthy young men is associated with decreased leptin levels

Subjects with a high score of type 2 pattern reported high consumption of food, alcohol and cigarettes. Especially, they had high ɤ-GTP, uric acid, and triglyceride levels. These findings suggest the presence of alcohol-related metabolic dysfunctions. Also, the results of the multivariate regression analysis supported these findings. It is also plausible that the high BP found in these patients was due to the high consumption of alcohol and cigarette [36].

In general, subjects preferring eveningness have been shown to make a custom of adverse health behaviors such as smoking, alcohol use, and physical inactivity compared to those preferring morningness in the general population [37]. In contrast, subjects with a high score of type 2 pattern showed morning type despite having unfavourable habits such as high consumption of alcohol and cigarettes. The exact reason(s) for this discrepancy is (are) not clear at present. However, short sleep duration was reported to be associated with high alcohol consumption [38]. In this study, subjects with a high score of this pattern reported short sleep duration. The latter could adversely affect the classification of morningness-eveningness.

Our study also identified a unique clustered lifestyle characterized by physical activity. The results of multivariate adjusted model demonstrated no correlation with the beneficial cardio-renal-metabolic parameters in subjects with a high score of this pattern, except uric acid. Rather, these subjects had high AST and ALT levels. This is possibly because higher consumption of food could cancel the beneficial effects of habitual physical activity on cardio-renal metabolic parameters. These data suggest the presence of antagonistic effect of lifestyle patterns that tend to accumulate in real daily life on cardio-renal-metabolic parameters.

The present study has certain limitation. First, the cross-sectional design does not allow inference of causal relationship between lifestyle patterns and cardio-renal-metabolic parameters. Also, we could not exclude the possibility that subjects change their daily lifestyles at other periods. Second, we did not confirm the validity and reproducibility of the lifestyle patterns found in this study in a different Japanese population. In this regard, we assessed the validity and reproducibility of the lifestyle patterns in this study by the following steps: 1) Subjects data in this study were randomly divided into two datasets (test and validation groups) in half, 2) The lifestyle patterns were evaluated by factor analysis in each dataset, and 3) Steps 1) and 2) were repeated ten times. According to this analysis, the lifestyle patterns evaluated by factor analysis in test and validation groups were similar, and the results were almost identical to those in the whole population (data not shown), suggesting that validity and reproducibility of the lifestyle patterns were relatively high in an internal. Finally, there may be other lifestyle patterns that should be considered, although based on the results of previous reports, we chose the possible lifestyle factors related to cardio-renal—metabolic parameters such as sleep quality [10,39], morningness-eveningness trait [14,40,41], depression status [17,18], energy intake and physical activity [35], smoking [42] and alcohol consumption [43].