Introduction
Methods
Participants and the Super Diet Education (Shokuiku) Project
Instruments
Data analysis
Results
Junior (1–3) | Senior (4–6) | ||
---|---|---|---|
Total n = 1663 | n = 826 (%) | n = 837 (%) | P value |
Sex (boy) | 50.1 | 49.6 | 0.83 |
Wakeup time on week day | |||
< 6:30 a.m. | 52.8 | 48.6 | 0.07 |
6:30 to < 7:00 | 44.2 | 46.6 | |
≥ 7:00 | 3.0 | 4.8 | |
Skipping breakfast (yes) | 4.5 | 8.7 | < 0.001 |
Screen time on week day (≥ 2 h) | 34.5 | 43.2 | < 0.001 |
Physical activity | |||
Very often | 28.3 | 28.7 | < 0.001 |
Often | 48.8 | 39.7 | |
Rarely | 22.9 | 31.7 | |
Bedtime on week day | |||
< 10 p.m. | 88.6 | 53.7 | < 0.001 |
10 to < 10:30 | 9.2 | 31.2 | |
10:30 or later | 2.2 | 15.2 | |
Daytime sleepiness (yes) | 12.8 | 20.9 | < 0.001 |
Obesity (yes) | 8.2 | 7.8 | 0.73 |
Cram school (yes) | 23.0 | 27.0 | 0.06 |
Study duration at home (< 1 h) | 74.8 | 50.3 | < 0.001 |
Paternal smoke (yes) | 42.1 | 46.2 | 0.09 |
Maternal smoke (yes) | 10.2 | 11.7 | 0.32 |
Subjective SES | |||
High | 28.3 | 26.9 | 0.73 |
Middle | 47.8 | 47.9 | |
Low | 23.8 | 25.2 | |
Subjective academic performance | 0.20 | ||
Well or relatively well | 82.4 | 81.6 | |
Neither | 11.9 | 14.1 | |
Relatively poor or poor | 5.7 | 4.3 |
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 | |||||
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
|
Junior grade (1 to 3) | Senior grade (4 to 6) | |||||
---|---|---|---|---|---|---|
Low academic | Univariate | Multivariatea | Univariate | Multivariatea | ||
% | OR (95% CI) | OR (95% CI) | % | OR (95% CI) | OR (95% CI) | |
Sex (girl/boy) | 15.8/19.3 | 0.78 (0.55–1.12) | 0.79 (0.54–1.16) | 19.0/17.8 | 1.08 (0.76–1.53) | 1.30 (0.89–1.89) |
Wakeup time on week day | ||||||
< 6:30 a.m. | 14.7 | 1 | 1 | 14.7 | 1 | 1 |
6:30 to < 7:00 | 19.5 | 1.40 (0.97–2.03) | 1.27 (0.86–1.89) | 21.3 |
1.56 (1.08–2.25)
| 1.38 (0.94–2.03) |
≥ 7:00 | 40.0 |
3.88 (1.67–9.00)
|
3.47 (1.41–8.53)
| 27.5 |
2.19 (1.04–4.63)
| 1.84 (0.85–4.43) |
Skipping breakfast (yes/no) | 32.4/16.9 |
2.37 (1.16–4.83)
| 1.27 (0.56–2.87) | 23.3/17.9 | 1.39 (0.78–2.47) | 0.99 (0.53–1.84) |
Screen time on week day (≥ 2 h/< 2 h) | 23.5/14.4 |
1.82 (1.27–2.63)
| 1.45 (0.98–2.15) | 21.3/16.2 | 1.40 (0.98–1.98) | 1.29 (0.89–1.88) |
Physical activity | ||||||
Very often | 14.1 | 1 | 1 | 17.1 | 1 | |
Often | 16.6 | 1.22 (0.77–1.91) | 1.49 (0.92–2.40) | 20.5 | 1.25 (0.81–1.92) | 1.22 (0.78–1.90) |
Rarely | 23.8 |
1.90 (1.16–3.13)
|
1.84 (1.09–3.12)
| 17.0 | 0.99 (0.62–1.58) | 0.99 (0.61–1.62) |
Bedtime on week day (late/not late) late: ≥ 10 for junior and ≥ 10:30 for senior grades children | 22.3/16.9 | 1.41 (0.84–2.38) | 0.92 (0.51–1.64) | 19.7/18.2 | 1.10 (0.69–1.78) | 0.86 (0.51–1.46) |
Daytime sleepiness (yes/no) | 23.6/16.7 | 1.54 (0.95–2.52) | 1.41 (0.83–2.40) | 19.4/18.1 | 1.09 (0.71–1.66) | 0.98 (0.63–1.53) |
Obesity (yes/no) | 20.6/17.3 | 1.24 (0.67–2.30) | 1.00 (0.52–1.93) | 20.0/18.3 | 1.12 (0.59–2.10) | 1.17 (0.60–2.27) |
Cram school (no/yes) | 18.6/14.2 | 1.38 (0.87–2.17) | 1.01 (0.62–1.66) | 19.6/15.0 | 1.38 (0.91–2.09) | 1.03 (0.66–1.61) |
Study duration at home (< 1/≥ 1 h) | 19.7/11.1 |
1.98 (1.23–3.19)
|
1.81 (1.08–3.02)
| 23.5/13.2 |
2.02 (1.41–2.90)
|
1.92 (1.29–2.85)
|
Paternal smoke (yes/no) | 23.3/13.4 |
1.96 (1.37–2.82)
|
1.67 (1.13–2.48)
| 21.2/16.0 | 1.41 (0.99–2.00) | 1.27 (0.87–1.84) |
Maternal smoke (yes/no) | 35.7/15.5 |
3.03 (1.86–4.94)
|
2.28 (1.32–3.94)
| 27.6/17.2 |
1.83 (1.13–2.97)
| 1.56 (0.92–2.64) |
Subjective SES | ||||||
High | 14.5 | 1 | 1 | 13.3 |
1
|
1
|
Middle | 17.5 | 1.25 (0.80–1.95) | 1.15 (0.72–1.84) | 20.2 |
1.65 (1.04–2.59)
|
1.62 (1.02–2.58)
|
Low | 21.3 | 1.59 (0.97–2.62) | 1.38 (0.82–2.34) | 20.4 |
1.66 (1.00–2.77)
| 1.52 (0.92–2.57) |
Subjective SES (%) | Chi-square | Trend | |||
---|---|---|---|---|---|
High | Middle | Low |
p
|
p
| |
Wakeup time on week day ≥ 7:00 a.m. | 3.9 | 3.6 | 4.4 | 0.55 | 0.59 |
Skipping breakfast (yes) | 5.0 | 6.8 | 8.1 | 0.18 | 0.07 |
Screen time on week day (≥ 2 h) |
34.2
|
40.1
|
41.9
|
0.04*
|
0.02*
|
Physical activity | |||||
Very often | 28.1 | 28.0 | 29.9 | 0.82 | 0.86 |
Often | 46.0 | 43.6 | 43.4 | ||
Rarely | 25.9 | 28.4 | 26.7 | ||
Late bedtime on week day (≥ 10 for junior, and ≥ 10:30 for senior grades children) |
10.9
|
13.4
|
15.7
|
0.11
|
0.04*
|
Daytime sleepiness (yes) |
12.6
|
17.3
|
20.8
|
< 0.01*
|
< 0.01*
|
Obesity (yes) | 7.2 | 8.4 | 8.1 | 0.74 | 0.61 |
Cram school (yes) |
29.0
|
24.2
|
22.1
|
0.05
|
0.02*
|
Study duration at home (< 1 h) | 61.0 | 61.1 | 66.9 | 0.10 | 0.08 |
Paternal smoke (yes) | 42.0 | 45.6 | 43.9 | 0.47 | 0.56 |
Maternal smoke (yes) | 8.5 | 11.7 | 12.3 | 0.14 | 0.07 |