| Duration | Frequency (n) | Percentage of Frequency (%) |
| 1 - 3 hours | 43 | 21.5 |
| 4 - 6 hours | 58 | 29.0 |
| 7 - 9 hours | 61 | 30.5 |
| 10 - 12 hours | 21 | 10.5 |
| Above 12 hours | 17 | 8.5 |
| Total | 200 | 100.0 |