Intensity and Network Structure of Insomnia Symptoms and the Role of Mental Health During the First Two Waves of the COVID-19 Pandemic

Figures & data

Table 1 Paired t-Test Results for Insomnia Symptoms

Variable	Pre-Lockdown (Mean, SD)	Peri-Lockdown (Mean, SD)	Change (%)	t test (df)	P value	Cohen d
ISI total	6.00 (4.91)	8.77 (5.92)	46,2	−35.46 (5171)	< 0.001	−0.49
DIS	1.62 (0.87)	2.08 (1.18)	28,4	−30.50 (5171)	< 0.001	−0.42
DMS	1.76 (0.92)	2.28 (1.18)	29,5	−33.99 (5171)	< 0.001	−0.47
EMA	1.82 (1.00)	2.21 (1.24)	21,4	−24.52 (5171)	< 0.001	−0.34
Dissatisfaction	2.60 (1.00)	3.13 (1.12)	20,4	−30.81 (5171)	< 0.001	−0.43
Interference	1.84 (0.95)	2.19 (1.10)	19,0	−23.85 (5171)	< 0.001	−0.33
Noticeability	1.63 (0.86)	1.87 (0.98)	14,7	−18.23 (5171)	< 0.001	−0.25
Worry	1.73 (1.00)	2.02 (1.02)	16,8	−19.85 (5171)	< 0.001	−0.28
Sleep quantity	3.33 (0.95)	3.25 (1.09)	−2,4	4.35 (5171)	< 0.001	0.06
DSA	1.57 (0.77)	1.68 (0.88)	7,0	−8.29 (5171)	< 0.001	−0.12
Mental fatigue	2.28 (1.02)	2.68 (1.20)	17,5	−25.02 (5171)	< 0.001	−0.35
Physical fatigue	1.93 (0.93)	2.06 (1.10)	6,7	−9.04 (5171)	< 0.001	−0.13
Anxiety	1.83 (0.88)	2.44 (1.04)	33,3	−43.50 (5171)	< 0.001	−0.61
Depression	1.46 (0.78)	1.81 (0.99)	24,0	−29.54 (5171)	< 0.001	−0.41

Notes: Scale going from 1 to 5, except for ISI total. Bold percentages in the column change signify a change of more than 30%.

Figure 1 Regularized GGMs of insomnia symptoms.

Notes: Each node represents a variable. Weight of edges (connection between nodes) is represented by the thickness and the color saturation of the edges. Positive connections are green and negative connections red. The pie chart surrounding each node represents node predictability. (A) Pre-lockdown network. (B) Peri-lockdown network.

Figure 2 Centrality measures.

Notes: Peri, peri-lockdown; Pre, pre-lockdown.

Table 2 Statistically Differing Edges Between Pre- and Peri-Lockdown GGMs

Edge	Pre-Lockdown Edge Weight	Peri-Lockdown Edge Weight	P value
DIS - DMS	0.13	0.00	< 0.001
Interference - Noticeability	0.51	0.41	< 0.001
DIS - Sleep quantity	0.00	0.04	0.03
DMS - Sleep quantity	−0.02	−0.11	< 0.001
Sleep quantity - DSA	−0.10	−0.02	0.02
Interference - Depression	0.00	0.11	0.02

Note: With Bonferroni correction.

Table 3 Paired t-Test Results for Insomnia Symptoms

Variable	Pre-Lockdown (Mean, SD)	Peri-Lockdown (Mean, SD)	Change (%)	t test (df)	P value	Cohen d
ISI total	6.14 (5.05)	10.38 (6.55)	69,1	−33.31 (2102)	< 0.001	−0.73
DIS	1.78 (0.93)	2.25 (1.22)	26,4	−20.20 (2102)	< 0.001	−0.44
DMS	1.82 (0.97)	2.51 (1.27)	37,9	−27.62 (2102)	< 0.001	−0.60
EMA	1.80 (0.96)	2.43 (1.31)	35,0	−25.63 (2102)	< 0.001	−0.56
Dissatisfaction	2.56 (0.96)	3.31 (1.10)	29,3	−30.01 (2102)	< 0.001	−0.65
Interference	1.82 (0.94)	2.51 (1.2)	37,9	−28.57 (2102)	< 0.001	−0.62
Noticeability	1.64 (0.88)	2.12 (1.09)	29,3	−22.06 (2102)	< 0.001	−0.48
Worry	1.72 (0.95)	2.25 (1.14)	30,8	−23.31 (2102)	< 0.001	−0.51
Sleep quantity	3.37 (0.90)	2.98 (1.08)	−11,6	15.53 (2102)	< 0.001	−0.34
DSA	1.60 (0.80)	1.93 (1.01)	20,6	−16.94 (2102)	< 0.001	−0.37
Mental fatigue	2.42 (1.04)	3.25 (1.24)	34,3	−32.00 (2102)	< 0.001	−0.70
Physical fatigue	2.12 (0.99)	2.52 (1.21)	18,9	−16.58 (2102)	< 0.001	−0.36
Anxiety	1.92 (0.93)	2.65 (1.18)	38,0	−31.29 (2102)	< 0.001	−0.68
Depression	1.52 (0.86)	2.20 (1.19)	44,7	−29.90 (2102)	< 0.001	−0.65

Note: Scale going from 1 to 5, except for ISI total. Bold percentages in the column change signify a change of more than 30%.

Figure 3 Regularized GGMs of insomnia symptoms.

Notes: Each node represents a variable. Weight of edges (connection between nodes) is represented by the thickness and the color saturation of the edges. Positive connections are green and negative connections red. The pie chart surrounding each node represents node predictability. (A) Pre-lockdown network. (B) Peri-lockdown network.

Figure 4 Centrality measures.

Notes: Peri, peri-lockdown; Pre, pre-lockdown.

Table 4 Statistically Differing Edges Between Pre- and Peri-Lockdown GGMs

Edge	Pre-Lockdown Edge Weight	Peri-Lockdown Edge Weight	P value
DIS - DMS	0.21	0.05	< 0.001
Dissatisfaction - Noticeability	0.00	0.05	< 0.001
Interference - Noticeability	0.53	0.44	0.02
Sleep quantity - DSA	−0.09	0.00	< 0.001
Mental fatigue – Physical fatigue	0.46	0.30	< 0.001

Note: With Bonferroni correction.

Figure 5 Directed acyclic graphs (DAGs).

Notes: (A) The thickness of an arrow indicates its importance to the overall network model fit (BIC value). Greater thickness indicates a greater contribution to model fit (non-significant arcs are plotted as dashed lines). (B) The thickness of an arrow indicates the likelihood of a given direction. Greater thickness corresponds to higher proportions of bootstrapped networks with the arrow pointing in that direction.