Table 4. Linear regression of the factors predicting sleep quality of medical students.
| Variables | R | t | Standardized β |
| Age | 0.21 | 1.3 | 0.01 |
| Gender | 0.24* | -1.9 | -0.85* |
| Body mass index | -0.56 | 1.07 | 0.23 |
| Type of accommodation | -0.34 | 0.41 | 0.32 |
| Years of education | -0.65* | -1.8 | -0.81* |
| Marriage | -0.78* | -0.79 | -0.45* |
| Total sleep time | -0.3 | 1.8 | 0.21 |
| Take a nap during daytime occasionally | 0.28 | -0.73 | -0.09 |
| Smoke within 2 hours before bedtime | 0.61* | 1.6 | 0.86* |
| Eat heavy night meals near the bedtime | -0.09 | 0.46 | 0.08 |
| perform dynamic physical activities within 2 hours before a sleep | 0.59* | 0.81 | 0.65* |
| Go to bed thirsty or hungry | 0.27* | 1.9 | 0.76* |
| Think about day's events and worries at bed | 0.75* | 1.13 | 0.45* |
| Engage yourself with highly demanded activities near to bedtime like watching exciting movies | 0.63* | 1.7 | 0.51* |
| Use your bed for activities other than sleep | -0.09 | -0.53 | -0.08 |
| Sleep in uncomfortable bedroom (temperature, light, noise) | 0.05 | 1.02 | 0.26 |
| Sleep and wake at the different time during the week | 0.58* | 2.5 | 0.61* |
*P<0.05 Discussion