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

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.

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/m² or ≥ 30.0 kg/m², respectively.

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).

Our findings provide an understanding of the relationship between CUS and BMI and can serve as an instructive basis for the management of BMI.