Table 2.
Description of the Studies in Children Excluded from the Meta-Analyses
| Author | Year | Country | Study design and Population | Sample size (n) | Age (yr) | Definition of sleep and obesity | Outcome measures presented | Summary of findings | Reason for exclusion |
|---|---|---|---|---|---|---|---|---|---|
| Gupta w13 | 2002 | USA | Cross-sectional Heartfelt Study | 383 | 11–16 | TST BMI >85th percentile for age and sex and % body fat >25% male or 30% female | Logistic regression | Obesity and TST β = −1.62 (0.28 SE) OR: 0.20 (0.11 to 0.34) | Logistic regression for OR and β only-adolescent study |
| Hui w14 | 2003 | Hong Kong | Selected groups Student Health Service | 343 | 6–7 | Usual no. of h sleep BMI/overweight by HK reference categories | % short sleepers in 3 categories of BMI | Association between short sleep and obesity (% obese increased in short sleepers and decreased in long sleepers) | Case-control analysis Selected by BMI group |
| Knutson w15 | 2005 | USA | National Longitudinal Study of Adolescent Health | 4,555 | grade 7–12 13–18 | BMI and usual no. h sleep | β for sleep duration and BMI | Shorter sleep and obesity boys β= − 0.08 (−0.12 to −0.03) girls β = −0.02 (−0.06 to 0.01) | OR from logistic regression only. |
| Eisenmann w16 | 2006 | Australia | Australian Health and Fitness survey | 6,324 | 7–15 | Sleep time in bed at night. BMI and Waist by sleep duration categories | ORadj for age | Dose response relationship for short sleep and overweight in all age groups (from 7 to 16 yr) significant in boys but not girls. | βadj and ORadj for age |
| Dieu w17 | 2007 | Vietnam | Sample of 20 kindergartens in Ho Chi Minh City | 670 | 4–6 | Obesity by Cole IOTF definition.w45 Night sleep time | Prevalence ratios with CI | Prevalence ratio 0.85 in univariate regression for duration of sleep and overweight. Children with longer nighttime sleep had lower risk of obesity. | No OR or β available |
| Knutson w18 | 2007 | USA | Cross-sectional Child Development supplement of Panel Study of Income Dynamics | 767 boys 779 girls | 10–18 | 2-d time diary and self-reported TST. “Overweight” >95th percentile according to CDC and prevention growth charts | ORadj for self-reported 0.5 to 7 h sleep vs 9.2 to 19.0 h sleep and obesity. | Self reported short sleep duration vs longest sleep ORadj = 0.88 (0.45 to 1.69). However significantly higher risk of overweight with midrange self-reported sleep duration compared to longest sleep. | Reported ORadj. No linear regression. |
| Snell w19 | 2007 | USA | Longitudinal Panel Survey of Income Dynamics | 1,441 | 3–17 | Average nightly sleep, BMI and obesity by Cole et al.w45 | Linear regression BMI, nonlinear (% categories) and sleep and wake timings. | BMI at time 1 sig corr <8 h sleep | No OR for short sleep vs obesity or β for cross sectional analysis. Only mean BMI in sleep duration categories |
TST = Total Sleep Time; SE = standard error; BMI = Body Mass Index; β = regression coefficient; OR = odds ratio; Adj = adjusted; CI = confidence intervals; sd = standard deviation. Note: All references beginning with a W are available in the website version of this paper on the SLEEP website at www.journalsleep.org