Determinants of self-reported sleep quality in healthy sleepers and patients

Figures & data

Table 1. Subjective sleep and awakening quality questionnaire

Sleep quality SSA-1	Awakening quality SSA-2	Somatic complaints SSA-3
Did you sleep well? Did you have deep sleep? Did you have difficulties in falling asleep? Did you have difficulties in staying asleep? Did you have bad dreams? Did you have difficulties getting back to sleep? Did you wake up earlier than usual?	8. Did you feel giddy after awakening? 9. Did you feel disorientated? 10. Did you feel tired? 11. Were you in a good mood? 12. Did you feel interested in your surroundings? 13. Did you feel slowed down? 14. Was your attention/concentration reduced? 15. Did you feel refreshed and rested?	16. Any nausea after awakening? 17. Any headache? 18. Dryness of your mouth? 19. Any dizziness? 20. In coordination of movements?

Table 2. Characteristics of study sample (healthy controls n = 156 and all patients n = 95) and descriptive statistics of the sleep variables

Characteristics	Healthy controls		All patients
Age, mean (SD)	51.5 (9.7)		51.6 (12.2)
Female gender, N (%)	85 (54.1)		24 (25)
Subjective sleep parameters	Night 1	Night 2	Night 1	Night 2
SSA total score, median (IQR)	29 (7)	28 (6)	39 (11.75)	34 (12)
SSA-1 subjective sleep quality, median (IQR)	12 (5)	10 (4)	15.5 (8)	12 (7.75)
Objective sleep parameters
Total time in bed, mean (SD)	469.5 (29.5)	471.1 (30.6)	475.5 (29.1)	480.2 (34.5)
Total sleep time, mean (SD)	362 (65.1)	396.8 (49.4)	360.2 (79.4)	396.5 (67.7)
Sleep efficiency, mean (SD) %	77.1 (13)	84.3 (9.5)	75.6 (15.4)	82.6 (12.8)
Sleep onset latency, mean (SD)	22.8 (20.7)	18.1 (17)	21 (25.9)	13.8 (11.3)
Wake time after sleep onset, mean (SD)	75.8 (52.7)	50.6 (39.2)	83.5 (57.6)	59.4 (50.9)
Number of awakenings, mean (SD)	25.5 (12.3)	21.8 (10.7)	34 (20.8)	28.8 (19.4)
Total wake time, mean (SD)	107.6 (62.4)	74.3 (45.5)	115.3 (72.2)	83.7 (61.3)
Sleep stage 1, mean (SD)	43.5 (22.3)	40.7 (21.3)	62.4 (37.1)	60.7 (42.3)
Sleep stage 2, mean (SD)	202.1 (48.4)	215.6 (44.3)	197.3 (60.3)	208.7 (53)
Sleep stage 3, mean (SD)	28 (14.6)	33.2 (16.1)	25.6 (14.6)	30.7 (17.8)
Sleep stage 4, mean (SD)	25.7 (25.1)	28.3 (25.1)	13.1 (25.1)	19.8 (23.1)
REM stage, mean (SD)	62.7 (24.6)	79 (25.9)	61.8 (29.6)	76.6 (28.6)
Slow wave sleep, mean (SD)	53.8 (30.1)	61.5 (30.8)	38.7 (30)	50.5 (31.4)

Note: All sleep measurements are reported in minutes, unless stated otherwise.

Table 3. The association between objective and subjective sleep parameters based on the first night for healthy controls

	Sleep well		SSA-1		SSA total score
	r	p	r	p	r	p
TIB	.03	.74	.05	.51	.02	.77
TST	.31	<.001	−.32	<.001	−.34	<.001
SE	.32	<.001	−.36	<.001	−.37	<.001
WASO	.30	<.001	.41	< .001	.41	<.001
SOL	.09	.29	.04	.60	.01	.91
NAW	.15	.06	.27	.001	.22	.006*
TWT	.32	<.001	.36	<.001	.36	<.001
Stage 1	−.07	.40	.04	.60	.04	.64
Stage 2	−.21	.008*	−.24	.003*	−.29	<.001
Stage 3	−.18	.03	−.15	.06	−.13	.10
Stage 4	−.02	.84	−.04	.60	−.03	.76
REM	−.28	<.001	−.33	<.001	−.28	<.001
SWS	−.08	.35	−.08	.32	−.05	.51

Notes: Sleep well = SSA question: “Did you sleep well?”; SSA-1 = subjective sleep

quality subscore; TIB = (total) time in bed; TST = total sleep time; SE = sleep efficiency;

SOL = sleep onset latency; NAW = number of awakenings during the night;

TWT = total wake time; stage 1/stage 2/stage 3/stage 4/rapid eye movement (REM)/

slow wave sleep (SWS) = total time in a particular sleep stage.

Significant p-values are shown in bold.

*Correlations that are significant but between ˃.001 and ≤.01.

Table 4. The association between objective and subjective sleep parameters based on the second night for healthy controls

	Sleep well		SSA-1		SSA total score
	r	p	r	p	r	p
TIB	.18	.03	.06	.47	.06	.49
TST	−.08	.31	−.28	<.001	−.25	.002*
SE	−.21	.009*	−.34	<.001	−.29	<.001
WASO	.23	.005*	.34	<.001	.33	<.001
SOL	.05	.51	.14	.08	.05	.50
NAW	.28	<.001	.32	<.001	.29	<.001
TWT	.22	.006*	.35	<.001	.30	<.001
Stage 1	.004	.96	.09	.28	.09	.26
Stage 2	.05	.57	−.15	.06	−.14	.07
Stage 3	−.09	.25	−.03	.68	−.01	.92
Stage 4	−.05	.52	−.03	.69	−.04	.59
REM	−.05	.57	−.19	.02	−.17	.03
SWS	−.09	.25	−.05	.51	−.04	.61

Notes: Sleep well = SSA question: “Did you sleep well?”; SSA-1 = subjective sleep

quality subscore; TIB = (total) time in bed; TST = total sleep time; SE = sleep efficiency;

SOL = sleep onset latency; NAW = number of awakenings during the night;

TWT = total wake time; stage 1/stage 2/stage 3/stage 4/rapid eye movement (REM)/

slow wave sleep (SWS) = total time in a particular sleep stage.

Significant p-values are shown in bold.

*Correlations that are significant but between ˃.001 and ≤.01.

Table 5. The association between objective and subjective sleep parameters of the difference between the nights for healthy controls

	Sleep well		SSA-1		SSA total score
	r	p	r	p	r	p
TIB	.16	.04	.14	.08	.18	.03
TST	−.21	.009*	−.28	.001	−.22	.007*
SE	−.31	<.001	−.42	<.001	−.35	<.001
WASO	.24	.003*	.34	<.001	.29	<.001
SOL	.11	.16	.13	.10	.13	.12
NAW	.11	.16	.21	.010*	.18	.03
TWT	.32	<.001	.42	<.001	.37	<.001
Stage 1	.05	.51	.10	.20	.13	.11
Stage 2	−.10	.21	−.25	.002*	−.19	.02
Stage 3	−.05	.52	−.05	.51	−.11	.19
Stage 4	−.15	.07	−.09	.25	−.10	.22
REM	−.28	.001	−.23	.003*	−.19	.019
SWS	−.11	.18	−.08	.32	−.11	.19

Notes: Sleep well = SSA question: “Did you sleep well?”; SSA-1 = subjective sleep

quality subscore; TIB = (total) time in bed; TST = total sleep time; SE = sleep efficiency;

SOL = sleep onset latency; NAW = number of awakenings during the night;

TWT = total wake time; stage 1/stage 2/stage 3/stage 4/rapid eye movement (REM)/

slow wave sleep (SWS) = total time in a particular sleep stage.

Significant p-values are shown in bold.

*Correlations that are significant but between ˃.001 and ≤.01.

Table 6. The association between objective and subjective sleep quality (SSA-1) with the difference between the nights, displayed for all patients and various patient groups

Sleep parameters	All patients (N = 95)		Mental disorder group (N = 26)		Somatic disorder group (N = 69)
	r	p	r	p	r	p
TST	−.47	<.001	−.28	.17	−.51	<.001
TIB	.25	.02	−.07	.74	.44	<.001
SE	−.54	<.001	−.33	.10	−.60	<.001
WASO	.47	<.001	.33	.10	.50	<.001
TWT	.54	<.001	.34	.09	.61	<.001
SOL	.36	<.001	.31	.12	.38	.001
NAW	.24	.02	.17	.42	.26	.030
Stage 1	−.03	.80	.15	.46	−.05	.692
Stage 2	−.39	<.001	−.52	.007*	−.32	.007*
Stage 3	−.03	.79	−.01	.97	−.04	.766
Stage 4	−.05	.65	.08	.70	−.01	.437
REM	−.21	.04	−.18	.38	−.19	.119
SWS	−.04	.71	−.07	.75	−.05	.667

Notes: TIB = (total) time in bed; TST = total sleep time; SE = sleep efficiency;

SOL = sleep onset latency; NAW = number of awakenings during the night;

TWT = total wake time; stage 1/stage 2/stage 3/stage 4/rapid eye movement (REM)/

slow wave sleep (SWS) = total time in a particular sleep stage.

Significant p-values are shown in bold.

*Correlations that are significant but between ˃.001 and ≤.01.

Table 7. Displayed are the standard deviations and the zero-order correlations of the variables SSA-1 and TWT for each study population and each method separately

	Healthy controls	All patients	Mental disorder group	Somatic disorder group
Night 1
SD SSA-1	3.97	4.87	5.54	4.42
SD TWT	60.4	71.52	78.96	69.1
r =	.36	.34	.50	.26
Night 2
SD SSA-1	3.21	5.1	6.1	4.16
SD TWT	45.61	51.64	50.15	52.49
r =	.35	.33	.41	.27
Difference between nights
SD SSA-1	4.23	4.94	5.7	4.61
SD TWT	57.13	60.29	54.42	62.73
r =	.42	.55	.40 n.s.	.61

Notes: SSA-1 = subjective sleep quality subscore; TWT = total wake

time; SD = standard deviation; r = correlation coefficient; n.s. = not significant.