Table 1.
Demographic characteristics and correlations
| Mean | SD | 1 | 2 | 3 | 4 | 5 | 6 | |
|---|---|---|---|---|---|---|---|---|
| 1. Age | 19.78 | 1.74 | 1 | |||||
| 2. Gender | 0.71 | 0.45 | -0.03 | 1 | ||||
| 3. PMPU | 27.24 | 8.41 | -0.11** | -0.05 | 1 | |||
| 4. Sleep quality index | 2.94 | 2.58 | 0.02 | 0.00 | 0.37*** | 1 | ||
| 5. Cognitive flexibility | 73.27 | 12.82 | -0.02 | 0.02 | -0.20*** | -0.17*** | 1 | |
| 6. TMD | 154.53 | 27.53 | 0.01 | -0.05 | -0.18*** | -0.26*** | 0.62*** | 1 |
Note. Gender (0 = female, 1 = male); SD = standardized deviation; PMPU = problematic mobile phone use; TMD = time management disposition; a high sleep quality index indicated the poor sleep quality; **p < 0.01; ***p < 0.001