Time Perspective and Bedtime Procrastination: The Role of the Chronotype–Time Perspective Relationship

Figures & data

Table 1 Differences in Demographic Characteristics, BP, Chronotype and TP Between Pre- and Post-COVID-19 Outbreak Groups

Variables	All Sample	Pre-COVID-19 Outbreak	Post-COVID-19 Outbreak	U/χ^2	p
Demographic characteristics
n	628	267	361
Sex				2.930	0.087
Male	182 (29.0)^c	87 (32.6)^c	95 (26.3)^c
Female	446 (71.0)^c	180 (67.4)^c	266 (73.7)^c
Age, years	20.00 (2.00)^b	20.00 (3.00)^b	19 (1.00)^b	34,105.000	<0.001
Education, years	12.00 (2.00)^b	14.00 (3.00)^b	12 (0.00)^b	14,289.000	<0.001
BPS	2.89 (1.00)^b	2.76 (0.83)^a	3.00 (0.89)^b	56,776.500	<0.001
MEQ	52.00 (11.00)^b	51.84 (8.39)^a	53.00 (11.00)^b	48,831.500	0.776
ZTPI
Past-negative	3.15 (0.90)^b	3.15 (0.67)^a	3.10 (0.80)^b	46,858.500	0.552
Present-hedonistic	3.13 (0.53)^b	3.25 (0.47)^a	3.07 (0.47)^b	38,557.500	<0.001
Future	3.38 (0.62)^b	3.46 (0.62)^b	3.38 (0.54)^b	40,257.000	<0.001
Past-positive	3.56 (0.67)^b	3.67 (0.56)^b	3.44 (0.67)^b	36,375.000	<0.001
Present-fatalistic	2.89 (0.78)^b	2.89 (0.78)^b	3.00 (0.67)^b	49,925.000	0.440
DBTP score	2.54 (0.76)^b	2.42 (0.86)^b	2.65 (0.71)^b	56,694.000	<0.001
Low level of DBTP	82 (13.1)^c	36 (13.5)^c	46 (12.7)^c	0.074	0.785

Notes: ^aVariables are normally distributed. Data are presented as mean and standard deviation. ^bVariables are non-normally distributed. Data are presented as median and interquartile range. ^cThe categorical variables are presented as frequency and proportion. Statistically significant values (p < 0.05) were formatted in bold.

Abbreviations: BP, bedtime procrastination; BPS, Bedtime Procrastination Scale; COVID-19, Coronavirus Disease 2019; DBTP, Deviation from Balanced Time Perspective; MEQ, Morningness-Eveningness Questionnaire; n, number; TP, time perspective; ZTPI, Zimbardo Time Perspective Inventory.

Table 2 Correlations Between BP, Demographic Characteristics, Chronotype and TP in Pre- and Post-COVID-19 Outbreak Groups, Respectively

No	Variables	1	2	3	4	5	6	7	8	9	10	11
1	Sex^a		−0.165**	−0.046	0.093	−0.125*	−0.018	−0.056	0.049	0.088	0.014	−0.031
2	Age	0.029		0.164**	−0.086	−0.150	−0.032	−0.114*	0.041	0.005	−0.014	0.044
3	Education	0.110	0.895***		−0.038	0.063	0.026	0.087	−0.004	−0.021	0.103	0.045
4	BPS	0.098	−0.158**	−0.144*		−0.493***	0.194***	0.035	−0.172**	−0.053	0.107*	0.204***
5	MEQ	0.024	0.182**	0.160**	−0.518^***b		−0.172**	−0.058	0.162**	0.005	−0.154**	−0.168**
6	Past-negative	−0.038	−0.050	−0.064	0.291^***b	−0.112^*b		0.425***	0.016	−0.041	0.546***	0.571***
7	Present-hedonistic	0.055	−0.092	−0.094	0.158^**b	−0.116^b	0.343^***b		0.142**	0.253***	0.420***	0.017
8	Future	0.035	0.188**	0.173**	−0.389***	0.307***	−0.099	−0.149*		0.466***	−0.140**	−0.436**
9	Past-positive	0.085	0.141*	0.165**	−0.158**	0.148*	−0.215***	0.145*	0.264***		−0.070	−0.589***
10	Present-fatalistic	−0.033	−0.060	−0.089	0.290***	−0.195**	0.539***	0.455***	−0.256***	−0.150*		0.623***
11	DBTP score	−0.097	−0.086	−0.105	0.323***	−0.199**	0.781***	0.178**	−0.317***	−0.526***	0.727***

Notes: ^aA dummy variable is used to recode sex, defined as 1 for female and 0 for male. ^bThe correlations between two normally distributed continuous variables using Pearson’s correlation coefficient. Pre-COVID-19 outbreak group below the diagonal; Post-COVID-19 outbreak group above the diagonal. Bolded correlations remain statistically significant after Bonferroni corrections. *p < 0.05, **p < 0.01, ***p < 0.001.

Abbreviations: BP, bedtime procrastination; BPS, Bedtime Procrastination Scale; COVID-19, Coronavirus Disease 2019; DBTP, Deviation from Balanced Time Perspective; MEQ, Morningness-Eveningness Questionnaire; TP, time perspective.

Table 3 Hierarchical Regression Analyses Exploring the Effects of Chronotype and TP on BP in Pre- and Post-COVID-19 Outbreak Groups, Respectively

Variables	BPS
	Pre-COVID-19 Outbreak				ΔR^2	Post-COVID-19 Outbreak				ΔR^2
	B	β	t	p		B	β	t	p
Step 1					0.035					0.013
Sex^a	0.206	0.117	1.876	0.062		0.117	0.070	1.311	0.191
Age	−0.023	−0.062	−0.487	0.627		−0.052	−0.076	−1.343	0.180
Education	−0.046	−0.095	−0.740	0.460		−0.003	−0.002	−0.042	0.966
Step 2					0.253					0.258
MEQ	−0.050	−0.511	−9.653	<0.001		−0.043	−0.513	−11.231	<0.001
Step 3					0.100					0.024
Past-negative	0.255	0.208	3.380	0.001		0.168	0.152	2.486	0.013
Present-hedonistic	−0.068	−0.039	−0.654	0.514		−0.125	−0.081	−1.361	0.174
Future	−0.411	−0.223	−4.020	<0.001		−0.188	−0.103	−1.978	0.049
Past-positive	0.018	0.011	0.207	0.836		0.072	0.055	0.996	0.320
Present-fatalistic	0.057	0.042	0.629	0.530		−0.005	−0.004	−0.064	0.949

Notes: ^aDummies are created for sex (male = 0; female = 1). Statistically significant values (p < 0.05) were formatted in bold.

Abbreviations: BP, bedtime procrastination; BPS, Bedtime Procrastination Scale; COVID-19, Coronavirus Disease 2019; MEQ, Morningness-Eveningness Questionnaire; TP, time perspective; B, Unstandardized regression coefficient; β, Standardized regression coefficient.

Table 4 Unstandardized Direct, Indirect and Total Effects of SEM Models in Pre- and Post-COVID-19 Outbreak Groups, Respectively

Effects	Paths	Point Estimate	Product of Coefficients		BaC 95% CI		p
			SE	Z	Lower	Upper
Pre-COVID-19 outbreak
Total effect	Chronotype	−0.051	0.005	−10.20	−0.061	−0.041	<0.001
	↓
Indirect effect	Future	−0.010	0.003	−3.33	−0.016	−0.005	<0.001
	↓
Direct effect	BP	−0.041	0.005	−8.20	−0.052	−0.031	<0.001
Post-COVID-19 outbreak
Total effect	Chronotype	−0.043	0.004	−10.75	−0.051	−0.035	<0.001
	↓
Indirect effects	Past-negative	−0.003	0.001	−3.00	−0.005	−0.001	0.010
	Future
	↓
Direct effect	BP	−0.040	0.004	−10.00	−0.048	−0.032	<0.001

Notes: Unstandardized estimating of 5000 bootstrap sample. Statistically significant values (p < 0.05) were formatted in bold. Z = Point Estimate/SE. If the absolute value of the z-score is greater than 1.96, the effect is considered significant.

Abbreviations: BaC 95% CI, bias-corrected and accelerated 95% confidence intervals; BP, bedtime procrastination; COVID-19, Coronavirus Disease 2019; SE, standard error; SEM, structural equation modeling.

Figure 1 The results of structural equation modeling of the mediating roles of TPs in the association between BP and chronotype in pre- and post-COVID-19 outbreak samples. The effect of demographic characteristics (sex, age, and years of education) on BP was controlled in these models. All the coefficients in the figure are unstandardized. The model fit indices in the pre-COVID-19 outbreak sample: χ²/df = 1.743, p = 0.065, RMSEA = 0.053, GFI = 0.982, CFI = 0.987, NFI = 0.970, TLI = 0.972, IFI = 0.987. The model fit indices in the post-COVID-19 outbreak sample: χ²/df = 1.113, p = 0.347, RMSEA = 0.018, GFI = 0.991, CFI = 0.994, NFI = 0.946, TLI = 0.987, IFI = 0.994. *p < 0.05, **p < 0.01, ***p < 0.001.

Abbreviations: BP, bedtime procrastination; COVID-19, Coronavirus Disease 2019; TP, time perspective.