Evening types are prone to depression

Figures & data

Table 1. Sociodemographic, socioeconomic, and health-related characteristics across chronotypes.

	Chronotype
	Men			Women
Characteristic	Morning (49.8%)	Intermediate (43.1%)	Evening (41.6%)	Morning (50.2%)	Intermediate (56.9%)	Evening (58.4%)
Age (years; mean ± SD)	53.9 ± 12.9	48.4 ± 13.9	43.3 ± 13.1	52.3 ± 13.2	47.9 ± 14.0	44.2 ± 13.6
Education level (%)
Basic	33.0	19.4	15.6	27.8	17.7	21.6
Secondary	52.9	55.8	58.9	53.1	54.4	53.6
Higher	14.2	24.8	25.5	19.1	28.0	24.8
Smoked in past or present (%)
No	28.9	29.4	22.4	51.3	47.3	35.9
Yes	71.1	70.6	77.6	48.7	52.7	64.1
Systolic blood pressure (mm Hg; mean ± SD)	140.8 ± 19.0	136.9 ± 18.0	133.3 ± 17.0	136.8 ± 22.1	130.4 ± 19.4	127.6 ± 19.0
Diastolic blood pressure (mm Hg; mean ± SD)	81.9 ± 11.6	81.2 ± 11.3	80.4 ± 11.4	78.2 ± 10.8	76.1 ± 10.4	75.5 ± 10.9
Resting heart rate (beats in 30 s; mean ± SD)	33.6 ± 6.0	33.6 ± 5.8	35.7 ± 6.6	34.4 ± 5.8	34.6 ± 5.6	35.0 ± 6.0
Weight (kg; mean ± SD)	85.2 ± 14.3	84.2 ± 13.8	85.7 ± 14.9	71.3 ± 14.1	70.1 ± 13.9	71.5 ± 15.8
Waist circumference (cm: mean ± SD)	99.0 ± 11.8	96.6 ± 11.8	97.1 ± 12.6	88.3 ± 13.4	86.8 ± 13.4	87.5 ± 14.5

SD = standard deviation.

Table 2. Distribution (%) of depression indicators across chronotypes^a.

	Chronotype
	Men (N = 2792)			Women (N = 3268)
Depression indicator	Evening (n = 303)	Intermediate (11)* (n = 1075)	Morning (1) (n = 1414)	Evening (n = 425)	Intermediate (12) (n = 1416)	Morning (2) (n = 1427)
Have you had at least two weeks period during the last 12 months when you have felt depressed?
No	68.0	84.4	91.1	62.8	75.1	84.1
Yes	32.0	15.6	8.9	37.2	24.9	15.9
	Men (N = 2781)			Women (N = 3253)
	Evening (n = 303)	Intermediate (13) (n = 1070)	Morning (3) (n = 1408)	Evening (n = 423)	Intermediate (14) (n = 1415)	Morning (4) (n = 1415)
Have you had at least two weeks period during the last 12 months when you have lost interest in most of the things that normally feel good?
No	63.4	82.2	87.8	66.7	78.9	85.5
Yes	36.6	17.8	12.2	33.3	21.1	14.5
	Men (N = 2777)			Women (N = 3246)
	Evening (n = 302)	Intermediate (15) (n = 1068)	Morning (5) (n = 1407)	Evening (n = 423)	Intermediate (16) (n = 1409)	Morning (6) (n = 1414)
Depressive symptoms
None	57.6	78.5	86.0	56.7	71.3	81.4
1 symptom	16.2	9.9	6.9	15.8	11.6	7.3
2 symptoms	26.2	11.6	7.1	27.4	17.1	11.3
	Men (N = 2794)			Women (N = 3277)
	Evening (n = 304)	Intermediate (17) (n = 1076)	Morning (7) (n = 1414)	Evening (n = 426)	Intermediate (18) (n = 1425)	Morning (8) (n = 1426)
Depression diagnosed or treated during last 12 months
No	87.2	95.2	96.9	82.9	90.4	94.7
Yes	12.8	4.8	3.1	17.1	9.3	5.3
	Men (N = 2752)			Women (N = 3228)
	Evening (n = 297)	Intermediate (19) (n = 1067)	Morning (9) (n = 1388)	Evening (n = 422)	Intermediate (20) (n = 1405)	Morning (10) (n = 1401)
When was the last time you used medication for depression?
Last week	9.4	3.8	2.6	14.0	8.0	6.1
Last 12 months	4.0	.9	.5	2.2	2.1	1.3
>1 year ago	7.7	6.2	3.8	10.4	9.4	5.6
Never	78.8	89.0	93.0	73.5	80.5	86.9

^aEvening types as the reference category.

*Significance for (1) to (19): p < 0.001 and for (20): p = 0.004.

Table 3. Results from logistic regression models to identify independent predictors of depression^a.

	Odds	95% confidence limit
Chronotype	ratio	Lower	Upper
Depressive symptoms
Model 1
Evening types	3.86	3.23	4.61****
Intermediate types	1.77	1.55	2.02****
Model 2
Evening types	3.32	2.77	3.99****
Intermediate types	1.62	1.41	1.85****
Model 3
Evening types	3.06	2.43	3.87****
Intermediate types	1.56	1.30	1.87****
A diagnosis or treatment for depression
Model 1
Evening types	4.14	3.16	5.44****
Intermediate types	1.87	1.48	2.37****
Model 2
Evening types	4.09	3.08	5.42****
Intermediate types	1.83	1.44	2.32****
Model 3
Evening types	3.82	2.71	5.37****
Intermediate types	1.54	1.13	2.09**
Antidepressant medication
Model 1
Evening types	2.88	2.34	3.56****
Intermediate types	1.68	1.43	1.98****
Model 2
Evening types	3.09	2.48	3.84****
Intermediate types	1.72	1.46	2.03****
Model 3
Evening types	2.72	2.07	3.58****
Intermediate types	1.60	1.28	1.99***

^aModel 1, crude (univariate); model 2, controlled for gender and age; model 3, controlled for gender, age, education level, and smoking status. Morning types as the reference category.

*p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.

Table 4. Means ± standard deviations of health examination parameters by chronotype and depressive symptoms^a.

	Chronotype
Parameter	Morning types (N = 2616)	Intermediate types (N = 2284)	Evening types (N = 673)
Systolic blood pressure
No depressive symptoms	139.7 ± 21.0	134.4 ± 19.5****	130.9 ± 18.7****
1 depressive symptom	136.3 ± 19.8	129.9 ± 18.0****	128.4 ± 17.6**
2 depressive symptoms	132.0 ± 17.9**	129.9 ± 17.1****	128.6 ± 18.1****
Diastolic blood pressure
No depressive symptoms	80.3 ± 11.2	78.8 ± 11.2**	77.9 ± 11.1**
1 depressive symptom	80.4 ± 11.8	76.5 ± 10.3**	76.9 ± 10.1
2 depressive symptoms	77.7 ± 11.8*	77.3 ± 10.9****	76.9 ± 12.6*
Resting heart rate
No depressive symptoms	33.9 ± 5.9	34.2 ± 5.8	35.2 ± 6.4*
1 depressive symptom	33.9 ± 6.1	33.4 ± 5.3	34.7 ± 5.3
2 depressive symptoms	34.9 ± 5.9	34.2 ± 5.3	35.8 ± 6.3****
Waist circumference
No depressive symptoms	93.4 ± 13.5	91.2 ± 13.4****	91.0 ± 13.8****
1 depressive symptom	95.1 ± 13.9	88.5 ± 14.0****	90.7 ± 14.6*
2 depressive symptoms	94.5 ± 15.9	92.2 ± 14.5*	92.8 ± 16.0
Weight
No depressive symptoms	78.1 ± 15.5	76.5 ± 15.2*	77.2 ± 16.3*
1 depressive symptom	79.1 ± 15.9	73.5 ± 15.9*	76.7 ± 16.0
2 depressive symptoms	79.0 ± 18.2	77.3 ± 15.5*	78.1 ± 19.0

^aAnalyses of covariances adjusted for gender, age, education level, and smoking status. Morning types and those with no depressive symptoms as the reference categories.

*p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.