Morningness-eveningness and caffeine consumption: A largescale path-analysis study

Figures & data

Table 1. The comparison of the chronotype-groups regarding gender, age, caffeine consumption, and caffeine use disorder.

Variable	Morning-type (N = 389)	Neither-type (N = 1138)	Evening-type (N = 668)	χ^2 (df)/F(df)
Age [mean (SD)]	38.42 (10.68)^a	33.41 (8.78)^b	32.35 (8.74)^c	44.36 (2, 901.00)***
Gender, N of females (%)	121 (31.3)	345 (30.5)	178 (26.0)	5.10(2)
Total daily caffeine intake (mg) [mean (SE)]^&	236.69 (7.37)^ab	239.24 (4.20)^a	257.92 (5.40)^b	4.42(2)*
Coffee
Daily coffee consumer N (%)	303 (86.8)	902 (85.8)	547 (84.9)	0.68(3)
OR [95% CI] ^&	Ref.	1.21 [0.83–1.75]	1.12 [0.76–1.66]
Tea
Daily tea consumer N (%)	85 (23.7)	198 (18.5)	98 (14.8)	12.56(2)**
OR [95% CI] ^&	Ref.	0.78 [0.58–1.10]	0.63 [0.45–0.88]**
Energy drink
Daily energy drink consumer N (%)	8 (2.3)	30 (2.8)	44 (6.6)	19.18(2)***
OR [95% CI] ^&	Ref.	1.08 [0.48–2.39]	2.47 [1.13–5.38]*
Cola
Daily cola consumer N (%)	13 (3.7)	76 (7.0)	64 (9.7)	12.50(2)**
OR [95% CI] ^&	Ref.	2.14 [1.17–3.94]*	3.02 [1.62–5.63]**
Caffeine Use Disorder (CUD)
Severe CUD N (%)	40 (11.0)	134 (12.3)	115 (17.5)	11.93(2)**
OR [95% CI] ^&	Ref.	1.13 [0.76–1.68]	1.61 [1.07–2.43]*

Note: Means that have no superscript in common are significantly different from each other at p < .05.

^&: Age was controlled in the analysis.

Ref.: Reference group.

*p < .05; **p < .01; ***p < .001.

Table 2. Correlation matrix of key study variables.

	rMEQ	Wellbeing	CUD	Caff_total	Coffee	Tea	Energy drink
Wellbeing	.260***
CUD	−.103***	−.207***
Caff_total	<.001	−.029	.233***
Coffee	.016	−.029	.235***	.929***
Tea	.073**	.069**	−.072**	.170***	−.127***
Energy drink	−.121***	−.090***	.140***	.148***	−.052*	−.009
Cola	−.100***	−.066**	.053*	.111***	−.056*	−.017	.161***

Note: rMEQ = total score on the reduced Morningness-Eveningness Questionnaire, wellbeing = total score on WHO-5 Wellbeing Index, CUD = total score on Caffeine Use Disorder Questionnaire, caff_total = total daily caffeine consumption. Coffee, tea, energy drink, and cola are ordinal variables and refer to daily consumption in mg.

*p < 0.05, **p < 0.01, ***p < 0.001

Figure 1. Path analysis for the association of morningness, coffee, tea, energy drink, and cola consumption, caffeine use disorder (CUD) and wellbeing.

Note: Unstandardized regression coefficients, their standard errors (in brackets) and standardized coefficients (in parentheses) are presented in the figure. There are no standard errors and level of significance for standardized regression coefficients for WLSMW estimation. Those standardized regression coefficients are presented in the figure which are associated with significant unstandardized regression coefficients.*p < .01, **p < .001