Psychometric evaluation of the Hamburg Nightmare Questionnaire (HNQ)

Figures & data

Table 1. Sociodemographic information and nightmare frequency.

	Sample
Variable	Total sample	2014	2015–2016	Test
N	707	234	473
Age (M [SD; Min–Max])	31.3 (9.2; 17–65)	31.3 (9.5; 17–65)	31.3 (9.0; 17–58)	t = .082, df = 705, p = .94
Female sex (N [%])	138 (19.5)	55 (23.5)	83 (17.5)	Chi^2 = 3.5, p = .07
Education level attained (N [%]):				Chi^2 = 4.9, p = .43
Degree course	108 (15.3)	36 (15.4)	72 (15.2)
Technical school/college	60 (8.5)	23 (9.8)	37 (7.8)
A levels	107 (15.1)	31 (13.2)	76 (16.1)
Middle school	325 (46.0)	101 (43.2)	224 (47.4)
Secondary school	105 (14.9)	42 (17.9)	63 (13.3)
No information	2 (0.2)	1 (0.4)	1 (0.2)
Nightmare frequency (N [%])				M-W-U = 44,304,5,
≥ 1x per night	52 (7.4)	18 (7.7)	34 (7.2)	Z = −1.92, p = .06
≥ 1x per week	342 (48.4)	120 (51.3)	222 (46.9)
≥ 1x per month	189 (26.7)	58 (24.8)	131 (27.7)
Less frequently	82 (11.6)	19 (8.1)	63 (13.3)
No information	42 (5.9)	19 (8.1)	23 (4.9)

M = Mean; SD = Standard deviation; Min = Minimum; Max = Maximum; M-W-U = Mann-Whitney-U

Table 2. Factor loadings and communalities of the Hamburg Nightmare Questionnaire items after principal component analysis with Kaiser-normalization with Varimax-rotation (sample 2014, n = 234).

	Factors
	I	II	III	IV	V	Com
I Emotional involvement
The memories of my nightmares scare me	.71	.31	.31			.71
I feel like I am delivered to my dreams	.80					.70
My nightmares torment me	.76					.80
I am afraid of my nightmares	.83					.84
II Physiological involvement
I wake up sweat-drenched from the nightmare		.75				.64
I wake up with heart racing from the nightmare		.80				.72
I wake up from the nightmare and am out of breath		.74				.65
III Replicativity
The nightmares remind me of stressful situations	.40		.66			.69
I experience a past situation in the nightmare again	.42	.34	.64			.74
I did not experience the situations in my nightmares in reality			.91			.87
The events in my nightmares did not really happen			.90			.86
IV Reorientation
When I wake up, I can think of something other than the nightmare				.52	−.34	.49
Upon awakening from the nightmare, I know everything is alright				.80		.74
After the nightmare I can calm myself down				.81		.69
After waking up, I know immediately that I was just dreaming				.74		.70
V Dream recall
The content of the nightmares is blurry/confused					.88	.80
I can barely remember details of the dream					.87	.78

Com = communalities; factor loadings < .30 are not depicted

Table 3. Inter-correlations of the Hamburg Nightmare Questionnaire subscales (total sample, n = 707).

	Subscale	2	3	4	5
1	Emotional Involvement	.59***	.45***	.60***	−.19***
2	Psychophysiological Involvement	-	.36***	.45***	−.10*
3	Replicativity		-	.42***	−.28***
4	Reorientation			-	−.24***
5	Dream Recall				-

* p < .05; *** p < .001

Table 4. Internal consistency of the Hamburg Nightmare Questionnaire subscales.

		Sample
		2014 (n = 234)	2015–2016 (n = 473)
	Subscale	Cronbach’s α
I	Emotional Involvement	.89	.89
IV	Psychophysiological Involvement	.74	.77
II	Replicativity	.88	.82
III	Reorientation	.80	.77
V	Dream Recall	.76	.70
VI	Impairment	.94	.95

Table 5. Means, standard deviations and corrected item-scale-correlation of the Hamburg Nightmare Questionnaire items in the study sample (n = 707).

	M	SD	ri(t-i)
I Emotional Involvement	3.0	1.2
The memories of my nightmares scare me	3.2	1.4	.69
I feel like I am delivered to my dreams	3.1	1.4	.69
My nightmares torment me	3.0	1.4	.82
I am afraid of my nightmares	2.9	1.4	.81
II Psychophysiological Involvement	2.9	1.1
I wake up sweat-drenched from the nightmare	3.2	1.3	.53
I wake up with heart racing from the nightmare	3.1	1.3	.62
I wake up from the nightmare and am out of breath	2.4	1.3	.62
III Replicativity	3.1	1.2
The nightmares remind me of stressful situations	3.5	1.4	.62
I experience a past situation in the nightmare again	3.1	1.5	.69
I did not experience the situations in my nightmares in reality	3.0	1.4	.67
The events in my nightmares did not really happen	3.0	1.4	.71
IV Reorientation	2.5	0.9
When I wake up, I can think of something other than the nightmare	3.1	1.3	.49
Upon awakening from the nightmare, I know everything is alright	2.5	1.2	.70
After the nightmare I can calm myself down	2.2	1.1	.53
After waking up, I know immediately that I was just dreaming	2.3	1.2	.62
V Dream recall	2.8	1.1
The content of the nightmares is blurry/confused	2.8	1.2	.56
I can barely remember details of the dream	2.8	1.3	.56
VI Impairment	2.1	1.1
How much do the nightmares affect your social environment/close friends?	2.1	1.2	.78
How much do you feel limited by the nightmares on duty?	1.9	1.2	.77
How strongly do you feel affected by nightmares in family life?	2.1	1.3	.82
How much do the nightmares limit your physical performance?	1.9	1.2	.84
How strongly do you feel in your mental capacity affected by the nightmares?	2.1	1.2	.86
How strongly do the nightmares affect your mood during the day?	2.4	1.3	.76
How strongly do you feel in the everyday life affected by the nightmares?	2.2	1.2	.88

M = Mean; SD = Standard deviation; r_i(t−i) = corrected item-scale-correlation

Figure 1. Confirmatory factor analysis (see section 3.2 for model fit indices).

Emo = emotional involvement; Physio = psychophysiological involvement; HNQ = Hamburg Nightmare Questionnaire

Table 6. Multiple regression analyses of the Hamburg Nightmare Questionnaire subscales (total sample, N = 664).

	EMO		PHY		REP		REO		REC		IMP
Predictor	Β	t	β	t	β	t	β	t	β	t	β	t
Age	0.11	3.05**	0.17	4.68***	0.11	2.93**	0.01	0.14	−.04	−0.90	0.08	2.19*
Sex	0.00	−0.01	−0.04	−1.21	0.04	1.16	−0.01	−0.17	.01	0.24	0.12	3.62***
Education	−0.00	−0.08	−0.01	−0.35	−0.01	−0.16	−0.01	−0.35	.01	0.13	0.04	1.27
Nightmare frequency	0.40	11.96***	0.33	9.24***	0.20	5.47***	0.30	8.17***	−.04	−1.13	0.40	12.26***
PTSD-diagnosis	0.23	6.57***	0.16	4.34***	0.28	7.26***	0.18	4.58***	−.13	−3.24**	0.29	8.30***
	R = 0.53, adjusted R^2 = 0.27 (F = 50.9, df = 5, p < .001).		R = 0.45, adjusted R^2 = 0.20 (F = 33.1, df = 5, p < .001).		R = 0.41, adjusted R^2 = 0.17 (F = 27.2, df = 5, p < .001).		R = 0.38, adjusted R^2 = 0.14 (F = 21.7, df = 5, p < .001)		R = 0.16, adjusted R^2 = 0.02 (F = 3.6, df = 5, p < .01).		R = 0.57, adjusted R^2 = 0.32 (F = 63.2, df = 5, p < .001)

EMO = Emotional Involvement; PHY = Psychophysiological Involvement; REP = Replicativity; REO = Reorientation; REC = Dream Recall; IMP = Impairment; ** = p < .01; *** = p < .001