Table 2 Sleep problems and sleepiness while driving reported by Daily two shift and Alternating day shift bus drivers
From: Sleepiness while driving and shiftwork patterns among Korean bus drivers
Variables | Daily two shift (n = 128) | Alternating day shift (n = 204) | p-value |
|---|---|---|---|
N (%) or M ± SD | N (%) or M ± SD | ||
Sleep disorder diagnosed by a doctor | 8 (6.3) | 18 (8.8) | 0.3956 |
Sleeping time on workdays (h) | |||
  < 6 | 16 (12.5) | 74 (36.3) | <0.0001 |
 6–8 | 86 (67.2) | 106 (52.0) |  |
  ≥ 8 | 26 (20.3) | 24 (11.8) |  |
 M ± SD | 6.6 ± 1.0 | 6.0 ± 1.3 | <0.0001 |
Sleeping time on off-days (h) | |||
  < 6 | 3 (2.3) | 15 (7.4) | 0.0014 |
 6–8 | 35 (27.3) | 85 (41.7) |  |
  ≥ 8 | 90 (70.3) | 104 (51.0) |  |
 M ± SD | 8.2 ± 1.4 | 7.7 ± 1.6 | 0.0013 |
Karolinska sleepiness scale (KSS, M ± SD) | |||
 First | 3.3 ± 1.8 | 3.1 ± 1.9 | 0.3346 |
 Morning | 3.7 ± 1.8 | 3.4 ± 1.7 | 0.1355 |
 Post-lunch | 3.9 ± 1.8 | 5.4 ± 2.0 | <0.0001 |
 Afternoon | 3.0 ± 1.5 | 5.0 ± 2.0 | <0.0001 |
 Last | 3.3 ± 1.7 | 5.0 ± 2.3 | <0.0001 |
Severe sleepiness while driving (KSS ≥ 7) | |||
 First | 8 (6.3) | 15 (7.4) | 0.7001 |
 Morning | 11 (8.6) | 14 (6.9) | 0.5607 |
 Post-lunch | 13 (10.2) | 81 (39.7) | <0.0001 |
 Afternoon | 2 (1.6)a | 63 (30.9) | <0.0001 |
 Last | 6 (4.7) | 64 (31.4) | <0.0001 |