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Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts.

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Grøntved, Anders 
Jago, Russell 
Kriemler, Susi 
Northstone, Kate 


OBJECTIVES: To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents. METHODS: Individual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated. RESULTS: In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (β-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score. CONCLUSIONS: If the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents.


Funder: Bristol University

Funder: Loughborough University; Id:

Funder: Norges Idrettsh‐gskole


adolescent, body fat, child, sleep hygiene, sleep wake disorders, waist circumference, Adiposity, Adolescent, Body Mass Index, Child, Cross-Sectional Studies, Female, Humans, Male, Obesity, Sleep, Waist Circumference

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Pediatr Obes

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MRC (MC_UU_00006/5)
Medical Research Council (MC_UU_12015/3)
Medical Research Council (MC_UU_12015/7)
Medical Research Council (G0701877)
This work was supported by a British Heart Foundation Immediate Postdoctoral Basic Science Research Fellowship awarded to PJC (grant number: FS/17/37/32937), who is also a member of The White Rose Child & Adolescent Sleep Research Network which is funded by a White Rose Collaboration Grant. This work was further supported by the National Prevention Research Initiative (grant number: G0701877) ( The funding partners relevant to this award are: British Heart Foundation; Cancer Research UK; Department of Health; Diabetes UK; Economic and Social Research Council; Medical Research Council; Research and Development Office for the Northern Ireland Health and Social Services; Chief Scientist Office; Scottish Executive Health Department; The Stroke Association; Welsh Assembly Government and World Cancer Research Fund. This work was additionally supported by the Medical Research Council (grant numbers: MC_UU_12015/3 & MC_UU_12015/7), the Research Council of Norway (grant number: 249932/F20), an Australian Research Council (ARC) Discovery Grant (grant number: DP0664206), the National Health & Medication Research Council (grant numbers: APP274309 & APP1176885), Bristol University, Loughborough University, and the Norwegian School of Sport Sciences. The funders were not involved in the design of the study, the collection, analysis, or interpretation of the data, report writing, or the decision to submit the final report for publication.