Figure and Table | Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Table 1. Participants’ Characteristics (n = 3,751).

From: Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Characteristics		Men (n = 2,227), n (%)	Women (n = 1,492), n (%)	χ² p-Value
Depression				<0.001
	No	1,645 (73.9)	1,023 (68.6)
	Yes	582 (26.1)	469 (31.4)
Age (years)				<0.001
	20-29	345 (15.5)	466 (31.2)
	30-39	333 (15.0)	337 (22.6)
	40-49	608 (27.3)	376 (25.2)
	≥50	941 (42.3)	313 (21.0)
Electronic device use at work (hours per day)				<0.001
	<4	677 (30.4)	532 (35.7)
	4-7	1,093 (49.1)	600 (40.2)
	≥7	457 (20.5)	360 (24.1)
Internet use in private life (hours per day)				0.530
	<2	1,325 (59.7)	892 (59.9)
	2-4	754 (34.0)	489 (32.9)
	≥4	141 (6.4)	107 (7.2)
Job class				<0.001
	Low	1,286 (58.0)	1,218 (81.9)
	Intermediate	512 (23.1)	195 (13.1)
	High	421 (19.0)	75 (5.0)
Overtime (hours per month)				<0.001
	<30	1,698 (76.2)	1,195 (80.1)
	30-45	337 (15.1)	226 (15.1)
	≥45	192 (8.6)	71 (4.8)
Job control				0.004
	High	738 (33.1)	449 (30.1)
	Intermediate	748 (33.6)	468 (31.4)
	Low	741 (33.3)	575 (38.5)
Job demands				<0.001
	Low	1,116 (50.1)	577 (38.7)
	Intermediate	657 (29.5)	488 (32.7)
	High	454 (20.4)	427 (28.6)
Support at work				<0.001
	High	584 (26.2)	505 (33.8)
	Intermediate	822 (36.9)	543 (36.4)
	Low	821 (36.9)	444 (29.8)
Married				<0.001
	Yes	1,712 (77.0)	834 (56.0)
	No	511 (23.0)	654 (44.0)
Caregiving				0.372
	No	1,781 (80.6)	1,175 (79.4)
	Yes	429 (19.4)	305 (20.6)
Work-to-family conflict				<0.001
	Low	757 (34.3)	331 (22.4)
	Intermediate	765 (34.6)	525 (35.5)
	High	687 (31.1)	621 (42.0)
Family-to-work conflict				0.002
	Low	1,040 (47.3)	652 (44.2)
	Intermediate	588 (26.7)	362 (24.5)
	High	571 (26.0)	462 (31.3)
Heavy drinking				<0.001
	No	1,956 (92.9)	1,369 (95.6)
	Yes	149 (7.1)	63 (4.4)
Smoking				<0.001
	No	1,835 (83.0)	1,464 (98.8)
	Yes	375 (17.0)	18 (1.2)
Longstanding illness				<0.001
	No	1,408 (64.0)	1,146 (77.6)
	Yes	791 (36.0)	331 (22.4)
Poor sleep quality				<0.001
	No	1,543 (69.3)	951 (63.7)
	Yes	684 (30.7)	541 (36.3)
Sleep duration (hours per day)
	<6	487 (22.0)	363 (24.5)	0.205
	6-9	1,705 (77.1)	1,104 (74.6)
	≥9	19 (0.9)	12 (0.8)

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Table 2. Prevalence of Depressive Symptoms and Univariate Logistic Regression Analysis of Factors Associated with Depression.

From: Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Characteristics		Prevalence of depressive symptoms (%)	OR (95% CI)
Sex: female		31.4	1.30 (1.12-1.50)
Age (years)
	20-29	29.2	Ref
	30-39	29.2	1.00 (0.80-1.25)
	40-49	29.7	1.02 (0.84-1.25)
	≥50	25.6	0.83 (0.69-1.01)
Electronic device use at work (hours per day)
	<4	26.5	Ref
	4-7	26.8	1.02 (0.86-1.20)
	≥7	33.4	1.39 (1.15-1.69)
Internet use in private life (hours per day)
	<2	26.2	Ref
	2-4	29.8	1.20 (1.03-1.40)
	≥4	35.5	1.55 (1.18-2.05)
Job class
	Low	30.3	Ref
	Intermediate	27.6	0.88 (0.73-1.06)
	High	18.8	0.53 (0.42-0.68)
Overtime (hours per month)
	<30	26.1	Ref
	30-45	34.9	1.51 (1.25-1.83)
	≥45	35.7	1.57 (1.20-2.05)
Job control
	High	17.2	Ref
	Intermediate	26.7	1.75 (1.43-2.13)
	Low	39.2	3.10 (2.57-3.73)
Job demands
	Low	20.5	Ref
	Intermediate	29.4	1.61 (1.35-1.91)
	High	41.3	2.72 (2.28-3.25)
Support at work
	High	18.0	Ref
	Intermediate	25.8	1.58 (1.30-1.92)
	Low	39.3	2.94 (2.43-3.56)
Married
	No	33.5	1.45 (1.25-1.69)
Caregiving
	Yes	33.9	1.39 (1.17-1.66)
Work-to-family conflict
	Low	10.6	Ref
	Intermediate	23.0	2.52 (2.00-3.18)
	High	48.6	7.96 (6.39-9.93)
Family-to-work conflict
	Low	18.0	Ref
	Intermediate	25.3	1.54 (1.27-1.86)
	High	48.3	4.25 (3.57-5.05)
Heavy drinking
	Yes	34.9	1.40 (1.05-1.88)
Smoking
	Yes	27.3	0.94 (0.75-1.19)
Longstanding illness
	Yes	33.3	1.40 (1.20-1.62)
Poor sleep quality
	Yes	53.2	6.01 (5.15-7.02)
Sleep duration (hours per day)
	<6	39.2	1.93 (1.64-2.27)
	6-9	25.0	Ref
	≥9	22.6	0.87 (0.38-2.04)

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Table 3. Multivariable Logistic Regression Analysis of Factors Associated with Depression in Men.

From: Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Characteristics		Model 1	Model 2	Model 3
		OR (95% CI)	OR (95% CI)	OR (95% CI)
Age (years)
	20-29	Ref	Ref	Ref
	30-39	0.84 (0.58-1.22)	0.73 (0.48-1.11)	0.72 (0.46-1.14)
	40-49	1.03 (0.73-1.46)	1.02 (0.69-1.50)	0.85 (0.56-1.31)
	≥50	1.09 (0.76-1.56)	1.20 (0.80-1.80)	0.87 (0.55-1.38)
Electronic device use at work (hours per day)
	<4	Ref	Ref	Ref
	4-7	1.15 (0.90-1.48)	1.10 (0.84-1.45)	1.12 (0.83-1.50)
	≥7	1.08 (0.79-1.47)	1.01 (0.72-1.41)	1.04 (0.72-1.51)
Internet use in private life (hours per day)
	<2	Ref	Ref	Ref
	2-4	1.26 (1.01-1.57)	1.36 (1.07-1.74)	1.28 (0.98-1.68)
	≥4	1.62 (1.06-2.49)	1.89 (1.17-3.08)	1.83 (1.08-3.10)
Job class
	Low	Ref	Ref	Ref
	Intermediate	0.87 (0.66-1.15)	0.84 (0.62-1.14)	0.86 (0.62-1.19)
	High	0.60 (0.42-0.84)	0.58 (0.40-0.84)	0.61 (0.41-0.90)
Overtime (hours per month)
	<30	Ref	Ref	Ref
	30-45	0.95 (0.71-1.28)	0.73 (0.53-1.00)	0.70 (0.49-0.99)
	≥45	0.99 (0.67-1.45)	0.81 (0.54-1.23)	0.85 (0.55-1.33)
Job control
	High	Ref	Ref	Ref
	Intermediate	1.72 (1.31-2.27)	1.66 (1.23-2.23)	1.87 (1.35-2.59)
	Low	2.89 (2.19-3.80)	2.82 (2.09-3.80)	2.93 (2.11-4.07)
Job demands
	Low	Ref	Ref	Ref
	Intermediate	2.07 (1.62-2.65)	1.37 (1.04-1.79)	1.52 (1.13-2.04)
	High	3.45 (2.59-4.59)	1.55 (1.12-2.16)	1.67 (1.17-2.39)
Support at work
	High	Ref	Ref	Ref
	Intermediate	1.39 (1.05-1.86)	1.22 (0.89-1.65)	1.30 (0.93-1.82)
	Low	2.34 (1.76-3.12)	1.88 (1.38-2.56)	1.92 (1.37-2.69)
Married
	No	NA	1.74 (1.29-2.34)	1.52 (1.10-2.09)
Caregiving
	Yes	NA	1.07 (0.80-1.43)	1.02 (0.75-1.40)
Work-to-family conflict
	Low	NA	Ref	Ref
	Intermediate	NA	2.33 (1.68-3.23)	2.10 (1.48-2.99)
	High	NA	5.97 (4.15-8.59)	4.67 (3.14-6.94)
Family-to-work conflict
	Low	NA	Ref	Ref
	Intermediate	NA	1.36 (1.01-1.82)	1.32 (0.96-1.81)
	High	NA	2.82 (2.10-3.80)	2.49 (1.80-3.44)
Heavy drinking
	Yes	NA	NA	0.96 (0.60-1.53)
Smoking
	Yes	NA	NA	0.99 (0.72-1.36)
Longstanding illness
	Yes	NA	NA	1.35 (1.03-1.76)
Poor sleep quality
	Yes	NA	NA	4.58 (3.51-5.97)
Sleep duration (hours per day)
	<6	NA	NA	0.71 (0.52-0.95)
	6-9	NA	NA	1.00
	≥9	NA	NA	1.38 (0.37-5.21)

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Table 4. Multivariable Logistic Regression Analysis of Factors Associated with Depression in Women.

From: Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Characteristics		Model 1	Model 2	Model 3
		OR (95% CI)	OR (95% CI)	OR (95% CI)
Age (years)
	20-29	Ref	Ref	Ref
	30-39	1.12 (0.80-1.56)	1.00 (0.69-1.46)	0.97 (0.64-1.47)
	40-49	1.00 (0.70-1.42)	0.81 (0.55-1.21)	0.82 (0.53-1.28)
	≥50	0.91 (0.60-1.40)	0.85 (0.53-1.39)	0.71 (0.41-1.23)
Electronic device use at work (hours per day)
	<4	Ref	Ref	Ref
	4-7	0.83 (0.63-1.10)	0.75 (0.56-1.01)	0.85 (0.61-1.17)
	≥7	1.10 (0.80-1.50)	1.14 (0.82-1.61)	1.27 (0.88-1.83)
Internet use in private life (hours per day)
	<2	Ref	Ref	Ref
	2-4	1.36 (1.03-1.81)	1.44 (1.05-1.98)	1.21 (0.86-1.71)
	≥4	2.27 (1.43-3.63)	2.71 (1.65-4.47)	2.31 (1.32-4.05)
Job class
	Low	Ref	Ref	Ref
	Intermediate	0.99 (0.67-1.48)	0.93 (0.61-1.43)	0.87 (0.55-1.37)
	High	0.93 (0.49-1.78)	0.89 (0.44-1.79)	0.80 (0.37-1.70)
Overtime (hours per month)
	<30	Ref	Ref	Ref
	30-45	1.53 (1.11-2.11)	1.12 (0.79-1.59)	1.18 (0.80-1.73)
	≥45	1.68 (0.97-2.88)	1.20 (0.67-2.15)	1.23 (0.66-2.29)
Job control
	High	Ref	Ref	Ref
	Intermediate	1.42 (1.03-1.95)	1.29 (0.92-1.82)	1.16 (0.80-1.69)
	Low	2.12 (1.55-2.92)	2.04 (1.45-2.87)	1.74 (1.21-2.52)
Job demands
	Low	Ref	Ref	Ref
	Intermediate	1.43 (1.07-1.92)	1.08 (0.78-1.49)	0.97 (0.69-1.38)
	High	2.11 (1.57-2.85)	1.42 (1.02-1.98)	1.27 (0.88-1.82)
Support at work
	High	Ref	Ref	Ref
	Intermediate	1.63 (1.21-2.20)	1.45 (1.05-2.01)	1.43 (1.01-2.02)
	Low	3.08 (2.25-4.23)	2.48 (1.77-3.49)	2.25 (1.56-3.25)
Married
	No	NA	2.03 (1.49-2.76)	1.77 (1.26-2.48)
Caregiving
	Yes	NA	1.16 (0.85-1.59)	1.23 (0.87-1.75)
Work-to-family conflict
	Low	NA	Ref	Ref
	Intermediate	NA	1.90 (1.24-2.90)	1.49 (0.95-2.35)
	High	NA	4.84 (3.12-7.51)	3.61 (2.25-5.77)
Family-to-work conflict
	Low	NA	Ref	Ref
	Intermediate	NA	1.43 (1.01-2.03)	1.44 (0.99-2.10)
	High	NA	3.00 (2.13-4.23)	2.74 (1.89-3.99)
Heavy drinking
	Yes	NA	NA	1.46 (0.77-2.78)
Smoking
	Yes	NA	NA	0.67 (0.21-2.15)
Longstanding illness
	Yes	NA	NA	0.92 (0.65-1.29)
Poor sleep quality
	Yes	NA	NA	4.19 (3.11-5.66)
Sleep duration (hours per day)
	<6	NA	NA	0.80 (0.57-1.12)
	6-9	NA	NA	1.00
	≥9	NA	NA	0.32 (0.04-2.75)

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Table 5. Multivariable Logistic Regression Analysis of Factors Associated with Depression in All Participants.

From: Off-Duty Internet Use and Depression: The Japanese Civil Servants Study

Characteristics		Model 1	Model 2	Model 3
		OR (95% CI)	OR (95% CI)	OR (95% CI)
Sex: female		1.19 (1.01-1.40)	0.89 (0.74-1.07)	0.86 (0.70-1.05)
Age (years)
	20-29	Ref	Ref	Ref
	30-39	0.96 (0.75-1.22)	0.85 (0.64-1.12)	0.81 (0.60-1.10)
	40-49	1.00 (0.79-1.28)	0.90 (0.69-1.18)	0.82 (0.61-1.11)
	≥50	1.02 (0.78-1.33)	1.04 (0.77-1.41)	0.83 (0.59-1.16)
Electronic device use at work (hours per day)
	<4	Ref	Ref	Ref
	4-7	1.00 (0.84-1.21)	0.92 (0.76-1.13)	0.97 (0.78-1.20)
	≥7	1.10 (0.88-1.36)	1.06 (0.83-1.34)	1.13 (0.87-1.46)
Internet use in private life (hours per day)
	<2	Ref	Ref	Ref
	2-4	1.30 (1.09-1.55)	1.40 (1.16-1.70)	1.25 (1.01-1.54)
	≥4	1.86 (1.36-2.54)	2.20 (1.56-3.10)	1.98 (1.36-2.88)
Job class
	Low	Ref	Ref	Ref
	Intermediate	0.94 (0.75-1.18)	0.92 (0.72-1.17)	0.88 (0.68-1.15)
	High	0.68 (0.51-0.92)	0.68 (0.49-0.93)	0.66 (0.47-0.93)
Overtime (hours per month)
	<30	Ref	Ref	Ref
	30-45	1.18 (0.95-1.47)	0.88 (0.70-1.12)	0.90 (0.70-1.16)
	≥45	1.20 (0.88-1.63)	0.89 (0.64-1.24)	0.93 (0.65-1.33)
Job control
	High	Ref	Ref	Ref
	Intermediate	1.59 (1.29-1.95)	1.50 (1.20-1.88)	1.51 (1.18-1.91)
	Low	2.53 (2.06-3.11)	2.44 (1.96-3.05)	2.29 (1.80-2.92)
Job demands
	Low	Ref	Ref	Ref
	Intermediate	1.76 (1.46-2.12)	1.23 (1.00-1.51)	1.22 (0.98-1.53)
	High	2.75 (2.24-3.37)	1.52 (1.20-1.91)	1.48 (1.15-1.90)
Support at work
	High	Ref	Ref	Ref
	Intermediate	1.49 (1.21-1.83)	1.34 (1.07-1.67)	1.37 (1.08-1.74)
	Low	2.66 (2.16-3.29)	2.20 (1.75-2.75)	2.12 (1.66-2.70)
Married
	No	NA	1.92 (1.55-2.37)	1.67 (1.33-2.10)
Caregiving
	Yes	NA	1.11 (0.90-1.37)	1.11 (0.88-1.40)
Work-to-family conflict
	Low	NA	Ref	Ref
	Intermediate	NA	2.17 (1.68-2.81)	1.86 (1.41-2.45)
	High	NA	5.40 (4.09-7.12)	4.18 (3.10-5.63)
Family-to-work conflict
	Low	NA	Ref	Ref
	Intermediate	NA	1.37 (1.10-1.72)	1.39 (1.09-1.76)
	High	NA	2.83 (2.27-3.53)	2.60 (2.04-3.31)
Heavy drinking
	Yes	NA	NA	1.14 (0.79-1.64)
Smoking
	Yes	NA	NA	0.98 (0.73-1.33)
Longstanding illness
	Yes	NA	NA	1.16 (0.94-1.43)
Poor sleep quality
	Yes	NA	NA	4.27 (3.51-5.19)
Sleep duration (hours per day)
	<6	NA	NA	0.75 (0.61-0.94)
	6-9	NA	NA	1.00
	≥9	NA	NA	0.81 (0.28-2.39)

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