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Table 1 Background characteristics of the cross-sectional and prospective study samples (mean (SD) unless otherwise specified)

From: Cross-sectional and prospective associations between sleep, screen time, active school travel, sports/exercise participation and physical activity in children and adolescents

  Cross-sectional samples Prospective sample
9-y-olds n 15-y-olds n Baseline n Follow-up n
Girls 49.4%   51.0%   48.9%   48.9%  
Age (years) 9.6 (0.4) 2366 15.3 (0.6) 1554 9.6 (0.4) 517 15.2 (0.7) 517
Height (cm) 138.7 (6.6) 2342 169.6 (8.3) 1490 139.1 (6.4) 515 169.8 (8.4) 477
Weight (kg) 33.9 (6.8) 2343 60.7 (11.4) 1474 33.4 (6.3) 515 59.8 (10.5) 469
BMI (kg∙m−2) 17.5 (2.6) 2340 21.0 (3.3) 1473 17.2 (2.4) 515 20.7 (3.0) 469
SES
  Low 6.8% 153 5.9% 82 5.8% 29 5.8% 29
 Middle 37.7% 843 38.8% 543 35.5% 179 35.5% 179
 High 55.5% 1243 55.4% 776 58.7% 296 58.7% 296
Acc. WT (min/d) 804.5 (64.5) 2366 840.2 (89.5) 1554 817.4 (66.7) 517 824.5 (84.5) 517
MVPA (min/d) 92.1 (30.6) 2366 68.6 (26.3) 1554 98.2 (33.3) 517 69.5 (25.6) 517
Sleep (hrs/d)a 9.7 (0.8) 2102 8.1 (0.9) 1165 10.3 (0.6) 478 7.5 (0.7) 382
Screen time (hrs/d) 2.6 (1.3) 2081 3.9 (1.6) 1209 2.4 (1.3) 476 3.9 (1.6) 399
Active transport
 0–5 min/d 43.7% 926 52.3% 652 38.6% 188 48.9% 204
 6–15 min/d 35.8% 757 36.1% 450 40.5% 197 36.7% 153
  ≥ 16 min/d 20.5% 434 11.6% 1247 20.9% 102 14.4% 60
Sports/exercise
  ≤ 2 h/week 36.1% 762 30.2% 373 30.8% 150 28.6% 117
 3–7 h/week 53.1% 1119 46.8% 577 56.1% 273 43.8% 179
  ≥ 8 h/week 10.8% 228 23.0% 284 13.1% 64 27.6% 113
  1. SES, socioeconomic status; Acc. WT, accelerometer wear time; MVPA, moderate-to-vigorous physical activity; hrs/d, hours per day; min/d, minutes per day; hrs/week, hours per week. aPossible range 7.5–13.0 h/night (PANCS1); 5.5–13.0 h/night (PANCS2/pooled)