| Low academic | Univariate |  | Multivariatea |  |
---|---|---|---|---|---|
% | OR (95% CI) | p | OR (95% CI) | p | |
Sex (girl/boy) | 17.4/18.6 | 0.92 (0.72–1.19) | 0.53 | 1.00 (0.77–1.31) | 0.98 |
Senior grade (4–6)/junior (1–3) | 18.4 / 17.6 | 1.06 (0.82–1.36) | 0.65 | 1.11 (0.84–1.45) | 0.47 |
Wakeup time on week day | |||||
 < 6:30 a.m. | 14.7 | 1 |  | 1 |  |
 6:30 to < 7:00 | 20.4 | 1.49 (1.15–1.93) | < 0.01 | 1.36 (1.03–1.78) | 0.03 |
 ≥ 7:00 | 32.3 | 2.77 (1.59–4.81) | < 0.001 | 2.48 (1.36–4.50) | < 0.01 |
Skipping breakfast (yes/no) | 26.4/17.4 | 1.70 (1.09–2.65) | 0.02 | 1.10 (0.68–1.78) | 0.71 |
Screen time on week day (≥ 2 h/< 2 h) | 22.3/15.3 | 1.59 (1.24–2.05) | < 0.001 | 1.35 (1.04–1.76) | 0.03 |
Physical activity | Â | Â | Â | Â | Â |
 Very often | 15.6 | 1 |  | 1 |  |
 Often | 18.4 | 1.22 (0.89–1.66) | 0.22 | 1.30 (0.94–1.79) | 0.11 |
 Rarely | 19.8 | 1.34 (0.95–1.88) | 0.09 | 1.33 (0.93–1.90) | 0.11 |
Bedtime on week day (late/not late) late: ≥ 10 for junior, and ≥ 10:30 for senior grades children | 20.8/17.5 | 1.23 (0.87–1.76) | 0.24 | 0.87 (0.59–1.28) | 0.49 |
Daytime sleepiness (yes/no) | 21.0/17.4 | 1.27 (0.92–1.74) | 0.15 | 1.10 (0.78–1.54) | 0.58 |
Obesity (yes/no) | 20.3/17.8 | 1.18 (0.76–1.83) | 0.47 | 1.07 (0.67–1.70) | 0.78 |
Cram school (no/yes) | 19.1/14.7 | 1.37 (1.01–1.86) | 0.04 | 1.01 (0.73–1.40) | 0.96 |
Study duration at home (<1 h/≥ 1 h) | 21.5/12.5 | 1.89 (1.43–2.50) | < 0.001 | 1.82 (1.34–2.49) | < 0.001 |
Paternal smoke (yes/no) | 22.2/14.7 | 1.66 (1.29–2.14) | < 0.001 | 1.47 (1.12–1.92) | < 0.01 |
Maternal smoke (yes/no) | 31.3/16.3 | 2.34 (1.66–3.29) | < 0.001 | 1.87 (1.29–2.72) | < 0.001 |
Subjective SES | |||||
 High | 13.9 | 1 |  | 1 |  |
 Middle | 18.8 | 1.43 (1.04–1.97) | 0.03 | 1.37 (0.99–1.90) | 0.06 |
 Low | 20.8 | 1.62 (1.14–2.32) | < 0.01 | 1.48 (1.03–2.14) | 0.04 |