Table 2 Score of the PSQI components and PSQI total score in overall participants, nonsmokers, and cigarette smokers
Variables | Total | Nonsmokers | Smokers | P* |
|---|---|---|---|---|
(n = 26,035) | (n = 19,466) | (n = 6569) | ||
Subjective sleep quality, M ± SD | 0.82 ± 0.65 | 0.79 ± 0.64 | 0.91 ± 0.66 | < 0.001 |
Sleep latency, M ± SD | 0.77 ± 0.73 | 0.75 ± 0.72 | 0.82 ± 0.75 | < 0.001 |
 ≤15 min, % | 38.6% | 39.3% | 36.4% | – |
 16-30 min, % | 48.2% | 48.1% | 48.2% | – |
 31-60 min, % | 11.0% | 10.4% | 12.6% | – |
 > 60 min, % | 2.3% | 2.1% | 2.8% | – |
Sleep duration, M ± SD | 0.58 ± 0.78 | 0.55 ± 0.76 | 0.67 ± 0.81 | < 0.001 |
 > 7 h, % | 58.1% | 59.9% | 52.6% | – |
 5–7 h, % | 40.4% | 38.7% | 45.6% | – |
 < 5 h, % | 1.5% | 1.4% | 1.8% | – |
Habitual sleep efficiency*, M ± SD | 0.33 ± 0.73 | 0.32 ± 0.71 | 0.35 ± 0.76 | 0.047 |
 ≥85%, % | 78.6% | 78.9% | 77.9% | – |
 75–84%, % | 13.3% | 13.3% | 13.2% | – |
 65–74%, % | 4.6% | 4.5% | 4.7% | – |
 < 65%, % | 3.6% | 3.4% | 4.2% | – |
Sleep disturbance, M ± SD | 0.78 ± 0.55 | 0.75 ± 0.56 | 0.86 ± 0.52 | < 0.001 |
Need for sleep medications, M ± SD | 0.11 ± 0.38 | 0.11 ± 0.37 | 0.12 ± 0.42 | 0.807 |
 Not during the past month, % | 91.4% | 91.4% | 91.3% | – |
 Less than once a week, % | 6.9% | 7.1% | 6.3% | – |
 Once or twice a week, % | 1.4% | 1.3% | 1.8% | – |
 ≥3 times a week, % | 0.4% | 0.3% | 0.6% | – |
Daytime dysfunction, M ± SD | 0.88 ± 0.84 | 0.84 ± 0.83 | 1.00 ± 0.86 | < 0.001 |
PSQI total score, M ± SD | 4.26 ± 2.67 | 4.11 ± 2.62 | 4.72 ± 2.75 | < 0.001 |
sleep disturbances (PSQI > 5), % | 26.5% | 24.5% | 32.7% | < 0.001 |