Table 3.
Comparisons of age, sex, bedtime, sleepiness during classes, and frequency of participation in lessons or crammers between the study groups.
| NIU Group | PIU Group | Statistics | |
|---|---|---|---|
| (n = 2162) | (n = 108) | ||
| Age | χ2 = 0.079, p = 0.809 | ||
| 12 years old | 1706 (78.9%) | 84 (77.8%) | |
| 13 years old | 456 (21.1%) | 24 (22.2%) | |
| Sex | χ2 = 1.583, p = 0.237 | ||
| Male | 1067 (49.4%) | 60 (55.6%) | |
| Female | 1095 (50.6%) | 48 (44.4%) | |
| Bedtime on weekdays | χ2 = 91.954, p < 0.001 | ||
| Before or at 9:59 PM | 558 (25.8%) | 13 (12.0%) | |
| 10:00–10:59 PM | 899 (41.6%) | 34 (31.5%) | |
| 11:00–11:59 PM | 539 (24.9%) | 29 (26.9%) | |
| 12:00–12:59 AM | 140 (6.5%) | 20 (18.5%) | |
| At or after 1:00 AM | 26 (1.2%) | 12 (11.1%) | |
| Bedtime on holidays | χ2 = 153.804, p < 0.001 | ||
| Before or at 9:59 PM | 547 (25.3%) | 12 (11.1%) | |
| 10:00–10:59 PM | 801 (37.0%) | 24 (22.2%) | |
| 11:00–11:59 PM | 555 (25.7%) | 29 (26.9%) | |
| 12:00–12:59 AM | 192 (8.9%) | 14 (13.0%) | |
| At or after 1:00 AM | 67 (3.1%) | 29 (26.9%) | |
| Sleepiness during classes | χ2 = 29.272, p < 0.001 | ||
| None | 283 (13.1%) | 10 (9.3%) | |
| Rarely | 668 (30.9%) | 20 (18.5%) | |
| Sometimes | 702 (32.5%) | 37 (34.3%) | |
| Common | 393 (18.2%) | 23 (21.3%) | |
| Always | 116 (5.4%) | 18 (16.7%) | |
| Frequency of participation in lessons or crammers (measured only in surveys II and III) | χ2 = 0.455, p = 0.978 | ||
| None | 300 (20.5%) | 16 (21.6%) | |
| Less than once a week | 226 (15.5%) | 13(17.6%) | |
| 2 or 3 times a week | 634 (43.4%) | 31 (41.9%) | |
| 4 or 5 times a week | 205 (14.0%) | 9 (12.2%) | |
| 6 or 7 times a week | 97 (6.6%) | 5 (6.8%) |
Data are expressed as n (%). NIU: normal internet use (Young’s Diagnostic Questionnaire score, ≤4); PIU: problematic internet use (Young’s Diagnostic Questionnaire score, ≥5).