Catch-up sleep on free days and body mass index: results from the seventh Korea National Health and Nutrition Examination Survey, 2016

Study Objectives: We aimed to identify the relationship between duration of categorized catch-up sleep on free days (CUS) and measured body mass index (BMI) in adults using the data from the seventh Korean National Health and Nutrition Examination Survey (KNHANES VII), 2016. Methods: CUS duration was classified as <= 0, > 0-1, > 1-2, and > 2 hours. Being overweight or obese was defined as having a BMI >= 25.0 kg/m(2) or >= 30.0 kg/m(2), respectively. Results: Of 6,382 participants aged 19-80 years in the KNHANES VII survey of 2016, 201 and 583 participants were excluded because of shift -working and insufficient data, respectively. Of 5,598 participants, CUS was observed in 2,274 (44.9%) participants, of which 3,324 (55.1%), 1,043 (19.4%), 724 (14.7%), and 507 (10.8%) had CUS of <= 0, > 0-1, > 1-2, and > 2 hours, respectively; the prevalence of obesity was 5.6%, 5.6%, 4.8%, and 6.1%, respectively. The association between BMI and CUS duration showed a significant negative association in the CUS <= 0 hours group (beta [95% confidence interval], -0.394 [-0.646, -0.143], P = .002); however, other CUS groups did not show any significant association with BMI (CUS > 0-1 hours: -0.196 [-1.258, 0.865], P = .716; CUS > 1-2 hours, -0.542 [-1.625, 0.541], P = .325; CUS > 2 hours, -0.113 [-0.459, 0.233], P = .519). Conclusions: Our findings provide an understanding of the relationship between CUS and BMI and can serve as an instructive basis for the management of BMI.