Table 3. Multivariate logistic regression analysis of factors related to poor sleep quality.

Variable		OR (95% CI)	p-value
Age (<40 vs. ≥40 (ref))		1.24 (0.51–3.01)	0.631
Marital status (single (ref), married, divorced/separated)
	Married	3.11 (1.18–8.19)	0.022*
	Divorced/separated	2.22 (0.63–7.81)	0.214
Level of education (higher than primary school vs. primary school (ref))		0.67 (0.31–1.44)	0.302
Health problems (no (ref) vs. yes)		0.49 (0.20–1.17)	0.106
BMI (≤22.9 (ref), 23–24.9, ≥25)
	23–24.9	1.99 (0.73–5.40)	0.177
	≥25	0.76 (0.33–1.73)	0.51
Smoking habits (no (ref), used to, current)
	Used to smoke	1.65 (0.66–4.16)	0.286
	Current smoke	1.09 (0.48–2.51)	0.83
Coffee consumption (yes vs. no (ref))		0.57 (0.18–1.86)	0.352
Alcohol consumption (yes vs. no (ref))		2.71 (1.31–5.58)	0.007**
Use of energy drinks (yes vs. no (ref))		1.24 (0.57–2.70)	0.58
Exercise (no vs. yes (ref))		2.29 (1.07–4.88)	0.033*
Risk of OSA (yes vs. no (ref))		1.15 (0.43–3.06)	0.783
Years of bus driving ( >10 yr (ref) vs. ≤10 yr)		0.45 (0.20–1.00)	0.05
Driving shift(s) (day (ref), night, day or night)
	Night only	20.63 (4.88–87.25)	0.000**
	Day or night	17.04 (5.13–56.56)	0.000**
Driving hours per/route (≥5 h vs. <5 h (ref))		0.81 (0.39–1.72)	0.59
Rest period during each route (no vs. yes (ref))		0.78 (0.32–1.90)	0.588
Switching of drivers during routes (no vs. yes (ref))		2.45 (0.98–6.17)	0.057
Number of routes per day (1 ride (ref) vs. >1 ride)		1.33 (0.62–2.86)	0.461

*p<0.05, **p<0.01, dependent variable: sleep quality (poor and good sleep quality). OR: Odds ratio; CI: Confidence interval; BMI: Body mass index; OSA Obstructive sleep apnea.