Table 5.

Analysis of the effects of demographic, lifestyle, and work factors on SL

		Adjusted
		OR	95% CI			p
Age		1.00	0.98	–	1.01	0.69
Sex	(Ref: Male)	0.75	0.52	–	1.08	0.12
Body mass index		1.06	1.01	–	1.11	0.03
Lifestyle habit
Longer sleeping hours on weekends than on weekdays	(Ref: No)	0.77	0.55	–	1.07	0.12
Nightcap	(Ref: No)	1.06	0.73	–	1.52	0.77
Smoking	(Ref: Former and never)	0.94	0.53	–	1.68	0.84
Exercise habits	(Ref: Once a week or less)	0.99	0.66	–	1.49	0.96
Smartphone use at bedtime	(Ref: No)	1.42	0.99	–	2.06	0.06
TV watching in the bedroom	(Ref: No)	1.40	0.99	–	1.99	0.06
Water ingestion at bedtime	(Ref: No)	2.38	1.52	–	3.72	<0.01
Ingestion of a caffeinated beverage
Coffee	(Ref: One cup per day or less)	1.06	0.75	–	1.51	0.73
Green tea	(Ref: One cup per day or less)	1.21	0.88	–	1.67	0.24
Tea	(Ref: One cup per day or less)	1.06	0.71	–	1.58	0.77
Energy drink	(Ref: One cup per day or less)	0.50	0.18	–	1.35	0.17
Shift worker	(Ref: No)	1.19	0.68	–	2.08	0.55
Commuting time (hours)		1.04	0.76	–	1.42	0.82
Brief Scale for Job Stress
Workload		1.01	0.78	–	1.31	0.95
Mental workload		1.18	0.89	–	1.55	0.25
Problems in personal relationships		0.96	0.76	–	1.22	0.74
Job control		1.10	0.86	–	1.41	0.45
Reward from work		1.10	0.88	–	1.38	0.39
Support from colleagues and superiors		1.06	0.79	–	1.41	0.70

Statistical analyses were conducted using binomial logistic regression.

OR: odds ratio

CI: confidence interval

SL: sleep latency

Logistic regression analysis, n = 693.