Psychometric properties of the Insomnia Catastrophizing Scale (ICS) in a large community sample

Figures & data

Table 1. Exploratory factor analysis of the Insomnia Catastrophizing Scale—Nighttime (ICS-N).

		Factor loading	Communalities	Corrected item-total correlations
1	My poor sleep will always continue	0.72	0.52	0.70
2	There is nothing I can do to get to sleep	0.67	0.45	0.66
3	My physical health will be negatively affected	0.82	0.68	0.78
4	I will get far too little sleep tonight	0.70	0.49	0.69
5	My poor sleep will have serious consequences	0.84	0.71	0.79
6	My thoughts will race all night	0.76	0.57	0.75
7	My poor sleep will get worse	0.77	0.60	0.73
8	My physical appearance will be negatively affected	0.74	0.54	0.70
9	I will lose control over my ability to sleep	0.77	0.59	0.73
10	My poor sleep will result in a nervous breakdown	0.65	0.43	0.60
11	My ability to function will be seriously affected (e.g. work, physical exercise, housework)	0.71	0.50	0.69

Goodness-of-fit test: χ² = 650.92, p < 0.001.

Table 2. Exploratory factor analysis of the Insomnia Catastrophizing Scale—Daytime (ICS-D).

		Factor loading	Communalities	Corrected item-total correlations
1	I will feel awful all day	0.80	0.63	0.75
2	My poor sleep will have serious consequences today	0.84	0.70	0.80
3	I will feel worse and worse	0.74	0.55	0.71
4	I will function poorly all day	0.83	0.68	0.78
5	My daily activities will be seriously affected	0.84	0.70	0.79
6	I will lose control over my ability to function (e.g. work, physical exercise, housework)	0.76	0.58	0.73

Goodness-of-fit test: χ² = 163.42, p < 0.001.

Table 3. Discriminant validity of the Insomnia Catastrophizing Scale at Subscale- and Item-Level.

	Insomnia disorder
	Yes (n = 218)	No (n = 1397)
	M (SD)	M (SD)	t	d
ICS-N	14.9 (10.9)	3.0 (5.4)	15.82**	1.47
Item 1 (N)	1.6 (1.5)	0.2 (0.7)	12.55**	1.23
Item 2 (N)	1.7 (1.5)	0.4 (1.0)	12.37**	1.02
Item 3 (N)	1.4 (1.4)	0.2 (0.7)	12.42**	1.14
Item 4 (N)	2.1 (1.5)	0.6 (1.0)	14.28**	1.22
Item 5 (N)	1.1 (1.3)	0.2 (0.6)	10.06**	1.02
Item 6 (N)	1.6 (1.4)	0.3 (0.8)	13.37**	1.13
Item 7 (N)	1.0 (1.3)	0.1 (0.5)	10.11**	0.98
Item 8 (N)	1.2 (1.5)	0.2 (0.7)	9.68**	0.96
Item 9 (N)	1.0 (1.4)	0.1 (0.4)	9.43**	0.96
Item 10 (N)	0.6 (1.0)	0.1 (0.4)	7.29**	0.68
Item 11 (N)	1.6 (1.4)	0.4 (0.8)	12.35**	1.07
ICS-D	6.4 (5.9)	1.5 (3.2)	11.99**	1.08
Item 1 (D)	1.3 (1.3)	0.4 (0.8)	9.93**	0.82
Item 2 (D)	0.9 (1.2)	0.2 (0.6)	8.45**	0.77
Item 3 (D)	0.8 (1.2)	0.1 (0.5)	8.50**	0.83
Item 4 (D)	1.4 (1.4)	0.3 (0.7)	11.38**	1.01
Item 5 (D)	1.3 (1.2)	0.3 (0.7)	11.99**	0.98
Item 6 (D)	0.8 (1.2)	0.1 (0.5)	8.50**	0.76

ICS-D = Insomnia Catastrophizing Scale—daytime, ICS-N = Insomnia Catastrophizing Scale—nighttime. ** p < 0.001.

Table 4. Correlations between the two ICS subscales, related constructs, sleep parameters, and daytime impairment.

	ICS-N	ICS-D	APSQ	PSAS-C	HADS-A	SOL	WASO	EMA	TST
ICS-N
ICS-D	0.75**
APSQ	0.73**	0.70**
PSAS-C	0.56**	0.48**	0.52**
HADS-A	0.52**	0.50**	0.52**	0.58**
SOL ^a	0.39**	0.26**	0.38**	0.32**	0.19**
WASO ^a	0.29**	0.20**	0.27**	0.29**	0.21**	0.34**
EMA ^a	0.27**	0.23**	0.28**	0.27**	0.24**	0.19**	0.33**
TST ^b	0.31**	0.21**	0.30**	0.22**	0.18**	0.28**	0.34**	0.28**
DI	0.53**	0.60**	0.60**	0.45**	0.56**	0.20**	0.16**	0.21**	0.18**

Spearman’s rho, Eta, and Contingency Coefficient were used as correlation statistics. APSQ = Anxiety and Preoccupation about Sleep Questionnaire, DI = daytime impairment, HADS-A = Hospital Anxiety and Depression Scale—anxiety, ICS-N = Insomnia Catastrophizing Scale—nighttime, ICS-N = Insomnia Catastrophizing Scale—daytime, PSAS-C = Pre-Sleep Arousal Scale—cognitive subscale, SOL = sleep onset latency, WASO = wake after sleep onset, EMA = early morning awakening, TST = total sleep time. ^a 30 min or less versus 30 min or more. ^b More than 6 h versus 6 h or less. ** p < 0.01.