Table 1. Baseline subject characteristics according to new onset of poor sleep quality and short sleep duration.
| Variables | Total | Poor sleep quality | Short sleep duration | ||
|---|---|---|---|---|---|
| No. (%) | P value | No. (%) | P value | ||
| Mobile phone addiction score | 0.002 | 0.207 | |||
| Low (≤ 15) | 489 | 93 (19.0) | 113 (23.1) | ||
| Middle (>15 and ≤ 20) | 418 | 95 (22.7) | 112 (26.8) | ||
| High (> 20) | 218 | 68 (31.2) | 63 (28.9) | ||
| Computer use time, hr | 0.001 | 0.126 | |||
| < 2 | 786 | 157 (20.0) | 212 (27.0) | ||
| ≥ 2 | 339 | 99 (29.2) | 76 (22.4) | ||
| Television viewing, hr | 0.006 | 0.137 | |||
| < 2 | 751 | 152 (20.2) | 203 (27.0) | ||
| ≥ 2 | 374 | 104 (27.8) | 85 (22.7) | ||
| Study outside school, hr | 0.114 | < 0.001 | |||
| Low (< 2.5) | 303 | 81 (26.7) | 44 (14.5) | ||
| Middle (≥ 2.5 and < 4.5) | 412 | 83 (20.2) | 111 (26.9) | ||
| High (≥ 4.5) | 410 | 92 (22.4) | 133 (32.4) | ||
| Gender | 0.705 | < 0.001 | |||
| Male | 572 | 127 (22.2) | 113 (19.8) | ||
| Female | 553 | 129 (23.3) | 175 (31.7) | ||
| Health status | 0.010 | 0.786 | |||
| Good | 1,045 | 228 (21.8) | 266 (25.5) | ||
| Bad | 80 | 28 (35.0) | 22 (27.5) | ||
| Academic record | 0.098 | < 0.001 | |||
| Low | 236 | 65 (27.5) | 53 (22.5) | ||
| Middle | 624 | 139 (22.3) | 142 (22.8) | ||
| High | 265 | 52 (19.6) | 93 (35.1) | ||
| Residency region | 0.981 | 0.697 | |||
| Capital city (Seoul or Gyeonggi) | 244 | 56 (23.0) | 65 (26.6) | ||
| Metropolitan area | 396 | 91 (23.0) | 105 (26.5) | ||
| Other | 485 | 109 (22.5) | 118 (24.3) | ||
| Household income | 0.764 | < 0.001 | |||
| Very low | 136 | 32 (23.5) | 27 (19.9) | ||
| Low | 227 | 54 (23.8) | 44 (19.4) | ||
| High | 424 | 100 (23.6) | 103 (24.3) | ||
| Very high | 338 | 70 (20.7) | 114 (33.7) | ||
| Father's education | 0.152 | 0.001 | |||
| High school/lower | 490 | 122 (24.9) | 101 (20.6) | ||
| College/higher | 635 | 134 (21.1) | 187 (29.5) | ||
| Mother's education | 0.069 | 0.001 | |||
| High school/lower | 623 | 155 (24.9) | 135 (21.7) | ||
| College/higher | 502 | 101 (20.1) | 153 (30.5) | ||
| Total | 1,125 | 256 (22.8) | 288 (25.6) | ||