A double-edged sword: the association of daytime napping duration and metabolism related diseases in a Chinese population.

backgroundSome studies have suggested that daytime napping may increase the risk of type 2 diabetes. However, limited data have revealed the association between nap duration and other metabolic diseases. Data from the baseline survey of Lanxi Cohort Study, a population-based study of natural residents in Zhejiang Province, China, were used to investigate the relationship between nap duration and metabolic abnormalities.

methodsA total of 3236 participants underwent a physical examination, laboratory tests, and face to face interview. They were categorized into four groups according to nap duration. Logistic regression models were used to examine the odds ratios (ORs) of napping duration with four metabolism-related diseases. Stratified analysis was further used to explore the interaction effects of gender and age on results.

resultsCompared to the no daytime napping group, people who napped during the daytime for more than 1 h were independently associated with a greater prevalence of diabetes (OR 1.56). Those who napped during the daytime within a half hour showed a lower prevalence of fatty liver, dyslipidemia, and central obesity. To be more specific, those who habitually napped during the daytime for more than 1 h exhibited an increasing prevalence of diabetes among female older than 50 years old. Those who habitually napped during the daytime within a half hour exhibited a decreasing prevalence of fatty liver and dyslipidemia among male <50 years old, and that of central obesity among female <50 years old.

conclusionsShort daytime napping duration is associate with reduced rate of metabolism-related diseases and may protects people from negative health conditions, whereas long daytime napping duration is associate with higher prevalence of diabetes, which then can be harmful for health.