Nightmares affect the experience of sleep quality but not sleep architecture: an ambulatory polysomnographic study

Table 1 Sleep questionnaire results comparing frequent nightmare sufferers (NM) with healthy controls (HC)

Scale (questionnaire)	NM	HC	NM vs. HC		Effect size
Scale (questionnaire)			t	p	d
Daytime sleepiness (ESS)	9.53 ± 3.27	7.44 ± 2.68	−1.596	0.03*	0.70
Sleep quality (LISST)	21.04 ± 5.34	15.13 ± 6.10	−2.864	0.004*	1.03
Apnea symptoms (LISST)	5.40 ± 2.59	4.33 ± 0.82	−1.528	0.145	0.57
RLS symptoms (LISST)	7.67 ± 2.06	8.06 ± 3.49	0.381	0.706	0.13
Problems with sleep/wake pattern (LISST)	19.20 ± 6.33	15.69 ± 5.78	−1.615	0.059*	0.58
Insomnia symptoms (LISST)	17.87 ± 4.93	11.75 ± 4.28	−3.697	< 0.001*	1.33
Tiredness during the day (LISST)	15.47 ± 6.63	10.75 ± 4.17	−2.353	0.013*	0.86
Parasomnias (LISST)	18.68 ± 6.60	10.69 ± 4.70	−3.903	< 0.001*	1.40
Sleep quality (SF-B)	3.39 ± 0.59	3.88 ± 0.47	2.603	0.007*	0.92
Feeling of being refreshed (SF-B)	2.59 ± 0.77	3.09 ± 0.83	1.713	0.049*	0.62
Feeling balanced/relaxed in the evening (SF-B)	3.02 ± 0.59	3.69 ± 0.68	2.911	0.004*	1.05
Feeling exhausted in the evening (SF-B)	3.84 ± 0.59	3.94 ± 0.68	0.406	0.344*	0.16
Psychosomatic symptoms while sleeping (SF-B)	1.90 ± 0.73	1.66 ± 0.45	−1.112	0.139*	0.40

ESS: Epworth Sleepiness Scale [41], LISST: Landecker Inventar zur Erfassung von Schlafstörungen [39], SF-B: Schlaffragebogen-B [40].
Results are presented as mean ± standard deviation; effect sizes as d.
*One-tailed t-test.