Better alignment between circadian preference and sleep and work timings during COVID-19 did not benefit work engagement at home

Figures & data

Table 1. Demographic information for final sample of participants split by age.

	18–20 (n = 203)	21–30 (n = 143)	30+ (n = 60)	Overall (n = 406)
Gender
Male	15%	30%	27%	22%
Female	85%	70%	73%	78%
MEQr Score
Mean (SD)	11 (3.5)	14 (3.2)	16 (4.0)	13 (3.8)
Lockdown Employment
Worker	11%	71%	88%	44%
Student	70%	23%	3%	44%
Not Working	18%	6%	8%	13%

Figure 1. Distributions of (a) work day sleep duration, (b) free day sleep duration, (c) midpoint of sleep, and (d) social jetlag before (red) and during (blue) lockdown. Vertical dashed lines represent the means.

Table 2. Comparisons between pre-lockdown and lockdown for each sleep habit parameter. Means for sleep duration and social jetlag variables represent number of hours and minutes. Means of all other variables represent clock time (hh:mm). Standard deviations for all variables represent number of minutes. Z statistics, bonferroni-corrected p values, effect sizes (r), and number of observations for each wilcoxon matched-pairs test are also reported.

Sleep Habit	Pre-Lockdown Mean (SD)	Lockdown Mean (SD)	Z	p	r	n
Work Day Sleep Duration	7 hours 36 mins (±75 mins)	8 hours 19 mins (±85 mins)	−8.67	<0.001	0.43	406
Free Day Sleep Duration	8 hours 40 mins (±77 mins)	8 hours 50 mins (±88 mins)	−2.08	0.375	0.10	406
Work Day Sleep Onset	23:51 (±81 mins)	00:48 (±130 mins)	−10.55	<0.001	0.52	406
Free Day Sleep Onset	00:56 (±94 mins)	01:12 (±123 mins)	−3.52	0.004	0.17	406
Work Day Sleep Offset	07:27 (±89 mins)	09:08 (±139 mins)	−14.09	<0.001	0.70	406
Free Day Sleep Offset	09:36 (±100 mins)	10:02 (±125 mins)	−6.76	<0.001	0.34	406
Phase of Entrainment	04:50 (±89 mins)	05:30 (±122 mins)	−6.87	<0.001	0.40	288
Work Day Midpoint of Sleep	03:38 (±77 mins)	04:58 (±128 mins)	−13.79	<0.001	0.68	406
Free Day Midpoint of Sleep	05:15 (±89 mins)	05:37 (±116 mins)	−5.62	<0.001	0.28	406
Social Jetlag	61 mins (±51 mins)	20 mins (±39 mins)	−12.02	<0.001	0.60	406

Figure 2. Distributions of (a) work duration, (b) the midpoint of the working day, and (c) work engagement before (red) and during (blue) lockdown. Higher UWES-9 scores indicate greater work engagement. Vertical dashed lines represent the means.

Table 3. Comparisons between pre-lockdown and lockdown for each work habit parameter. Means and standard deviations for the work duration variable represent number of hours and minutes. Means and standard deviations for the work engagement variable represents score on the UWES-9 scale where higher scores indicate better work engagement. Means of all other variables represent clock time (hh:mm) and standard deviations for all other variables represent number of minutes. Z statistics, bonferroni-corrected p values, effect sizes (r), and number of observations for each wilcoxon matched-pairs test are also reported.

Work Habit	Pre-Lockdown Mean (SD)	Lockdown Mean (SD)	Z	p	r	n
Work Duration	8 hours 14 mins (±133 mins)	7 hours 18 mins (±184 mins)	−4.97	<0.001	0.30	275
Midpoint of Working Day	13:47 (±119 mins)	14:08 (±131 mins)	−3.58	0.002	0.22	276
Work Start Time	09:40 (±142 mins)	10:34 (±177 mins)	−5.97	<0.001	0.36	276
Work Finish Time	17:54 (±129 mins)	17:52 (±147 mins)	−0.25	1.00	0.01	276
Work Engagement	3.42 (±0.93)	2.61 (±1.17)	−12.05	<0.001	0.68	310

Figure 3. Scatterplots displaying circadian preference against (a) midpoint of sleep change, (b) social jetlag change, and (c) working day midpoint change. Positive values on the y axis indicate delayed lockdown sleep midpoint (3a) and working day midpoint (3c) compared to pre-lockdown, or increased social jetlag during lockdown compared to pre-lockdown. Densigram on the x axes (above the figures) displays the distribution of circadian preference (MEQr score). Densigram on the y axes (right of figures) displays the distribution of ∆ midpoint of sleep (3a), ∆ social jetlag (3b), and ∆ working day midpoint (3c).

Table 4. Model summary statistics for the three linear regression models with circadian preference as the only predictor variable and ∆ midpoint of sleep, ∆ social jetlag, or ∆ working day midpoint as the dependent variables (DVs).

Model DV	R^2	F	n	t	β	p
∆ Midpoint of Sleep	10.42%	34.39	288	−5.86	−7.49	<0.001
∆ Social Jetlag	6.1%	27.21	406	5.22	3.87	<0.001
∆ Working Day Midpoint	2.8%	9.03	276	−3.0	−5.79	0.003

Table 5. Model summary statistics for significant predictors in the final models of the three linear regression analyses with ∆ work engagement as the dependent variable, and demographic variables and either ∆ midpoint of sleep, ∆ social jetlag, or ∆ working day midpoint as the predictor variables (IVs). See supplementary table 2 for full model summary statistics of final models.

Key model IV	Contrast	R^2	F	p	n	t	β	p
∆ Midpoint of Sleep		8.9%	3.68	<0.001	220
	Students v Workers					3.22	0.54	0.001
∆ Social Jetlag		11.7%	6.85	<0.001	310
	∆ Social Jetlag					3.87	0.004	<0.001
	Males v Females					−2.01	−0.25	0.046
	Students v Workers					2.84	0.38	0.005
∆ Working Day Midpoint		8.8%	4.32	<0.001	276
	∆ Working Day Midpoint – Linear Term					−2.63	−0.001	0.009

Figure 4. Scatterplot displaying social jetlag change against work engagement change. Positive values on the x axis indicate that social jetlag was greater during lockdown compared to pre-lockdown. Positive value on the y axis indicate that work engagement was greater during lockdown compared to pre-lockdown. Densigram on the x axis (above the figure) displays the distribution of ∆ social jetlag. Densigram on the y axis (right of figure) displays the distribution of ∆ work engagement.

Figure 5. Scatterplot displaying working day midpoint change against work engagement. Positive values on the x axis indicate that the midpoint of the working day during lockdown was delayed (later) compared to pre-lockdown. Positive values on the y axis indicate that work engagement was greater during lockdown compared to pre-lockdown. Densigram on the x axis (above the figure) displays the distribution of ∆ working day midpoint. Densigram on the y axis (right of figure) displays the distribution of ∆ work engagement.

Data availability statement

The data and analysis scripts underlying this article are available on the Open Science Framework at https://osf.io/jnfrv/.