| due to insufficient sleep | 10 | cause |
| extremely | 8 | degree |
| behind the wheel | 6 | location |
| driver → be → fatigued | 157 |
| driver → become → fatigued | 32 |
| driver → be prone to → fatigue | 6 |
| driver → be likely to → become fatigued | 4 |
| driver → get → fatigued | 3 |
| negative | neutral | positive |
| 0.639 | 0.320 | 0.041 |
| Raw frequency | 202 |
| Normalized frequency | 0.662 |
| Modifier score | 0.700 |
| Perplexity | 31.527 |