Table 2.
Baseline characteristics of participants aged 7–12 years by sleep time.
| Sleep Time (h/day) | p Value a | ||||
|---|---|---|---|---|---|
| <8 | 8 | 9 | ≥10 | ||
| Participants (n) | 777 | 2758 | 3322 | 593 | |
| Female (%) | 58.6 | 49.5 | 46.5 | 47.7 | <0.0001 |
| Mean age (years) (SD) | 12.2 (1.1) | 10.9 (1.6) | 9.7 (1.5) | 9.2 (1.4) | <0.0001 |
| Mean SDQ (SD) | 10.4 (6.3) | 10.6 (6.1) | 11.1 (6.2) | 12.2 (6.8) | <0.0001 |
| Current state of health (%) | |||||
| Very good or good | 49.2 | 53.4 | 55.0 | 52.7 | 2 × 10−4 |
| Normal | 47.1 | 43.0 | 43.1 | 43.4 | |
| Poor or very poor | 3.6 | 3.6 | 1.9 | 3.9 | |
| Tsunami experience (%) | 11.6 | 12.4 | 11.4 | 11.3 | 0.618 |
| Nuclear reactor accident experience (%) | 42.7 | 41.4 | 37.7 | 40.0 | 0.007 |
| Evacuation to other prefectures (%) | 21.9 | 22.5 | 29.7 | 47.9 | <0.0001 |
| Respondent (%) | |||||
| Mother | 86.6 | 89.1 | 88.1 | 89.4 | 0.378 |
| Father | 11.3 | 9.2 | 9.6 | 8.9 | |
| Other | 2.1 | 1.7 | 2.3 | 1.7 | |
SD, standard deviation; a p values were calculated by a chi-squared test (categorical variables), or ANOVA (continuous variables).