Sleep better – Think better! – The effect of CBT-I and HT-I on sleep and subjective and objective neurocognitive performance in university students with insomnia

Figures & data

Figure 1. Flow chart of the experimental design. After the waiting period, the WLC received the SWIS sleep training. All participants who completed at least four of the six sessions were counted as completers. Dropout rates aside from non-completers were 41% in the SWIS condition and 21% in the WLC condition.

Table 1. Self-reported sleep qualit y at pre- and post-measurement according to PSQI scoring when not indicated otherwise

		Pre		post		Time effect		Condition effect		Interaction effect (N = 27)
		M	(SD)	M	(SD)
PSQI Sum Score	SWIS	10.83	(3.88)	8.50	(3.17)	FTime (1,23) = 9.459		FCondition (1, 23) = .437		FTime*Condition (1,23) = .616
	WLC	9.61	(3.33)	8.23	(2.20)	p = .005	ηG^2 = 084	p = .515	ηG^2 = .014	p = .441	ηG^2 = .001
PSQI Sleep Quality	SWIS	2.17	(0.71)	1.92	(0.49)	FTime (1,23) = 17.164		FCondition (1, 23) = 1.437		FTime*Condition (1,23) = .027
	WLC	1.92	(0.56)	1.30	(0.63)	p = .000	ηG^2 = .239	p = .243	ηG^2 = .034	p = .870	ηG^2 = .001
PSQI Sleep Disturbances	SWIS	1.36	(0.50)	1.18	(0.40)	FTime (1,20) = 2.759		FCondition (1, 20) = .000		FTime*Condition (1,20) = .000
	WLC	1.36	(0.62)	1.18	(0.60)	p = .112	ηG^2 = .028	p = 1.000	ηG^2 = .000	p = 1.000	ηG^2 = .000
PSQI Sleep Medication	SWIS	0.42	(0.90)	0.25	(0.45)	FTime (1,23) = .070		FCondition (1, 23) = .085		FTime*Condition (1,23) = .513
	WLC	0.38	(0.87)	0.46	(1.13)	p = .794	ηG^2= .001	p = .773	ηG^2 = .002	p = .481	ηG^2 = .005
PSQI Daytime Sleepiness	SWIS	2.00	(0.73)	1.58	(0.79)	FTime (1,23) = 4.258		FCondition (1, 23) = .324		FTime*Condition (1,23) = .096
	WLC	2.07	(0.64)	1.76	(0.73)	p = .051	ηG^2 = 063	p = .575	ηG^2 = .008	p = .759	ηG^2 = .001
Sleep Latency in Minutes	SWIS	53.10	(43.53)	39.80	(49.11)	FTime (1,26) =0.082		FCondition (1, 26) = 0.023		FTime*Condition (1,26) = 0.565
	WLC	40.96	(44.90)	46.92	(77.94)	p = .777	ηG^2 = .001	p = .880	ηG^2 = .001	p = .459	ηG^2 = .008
Sleep Duration in Hours	SWIS	6.13	(1.36)	6.64	(1.01)	FTime (1,25) = 4.371		FCondition (1, 25) = .639		FTime*Condition (1,25) = .190
	WLC	6.58	(1.40)	6.92	(1.34)	p = .047	ηG^2 = .028	p = .432	ηG^2 = .020	p = .667	ηG^2 = .001
Sleep Efficiency in %	SWIS	70.44	(19.19)	79.91	(14.52)	FTime (1,25) = 5.267		FCondition (1, 25) = .058		FTime*Condition (1,25) = 1.274
	WLC	74.80	(11.90)	78.02	(12.04)	p = .030	ηG^2 = .061	p = .811	ηG^2 = .001	p = .270	ηG^2 = .021

Figure 2. Development of PSQI sum score, sleep duration and sleep efficiency in SWIS and WLC. Error bars for the standard error of the mean are displayed.Note: * p < .05; ** p < .01

Table 2. Summary of objective attention. Note. z = standardized z-value; T = standardized T-value, TAP = “test of attentional performance“

Attention		pre		post		Time effect			Condition effect		Interaction effect (N = 30)
		M	(SD)	M	(SD)
d2 Concentration (z)	SWIS	89.45	(9.96)	95.70	(10.98)	FTime (1,33) = 70.687			FCondition (1, 33) = .753		FTime*Condition (1,33) = .071
	WLC	92.47	(9.23)	98.33	(8.11)	p = .000	ηG^2= .091		p = .392	ηG^2 = .021	p = .792	ηG^2 = .001
TAP Alertness	SWIS	44.07	(8.55)	44.21	(7.83)	FTime (1,25) = .582			FCondition (1, 25) = 4.683		FTime*Condition (1,25) = .427
Reaction time (T)	WLC	49.15	(8.52)	51.00	(6.38)	p = .453	ηG^2 = .004		p = .040	ηG^2 = .133	p = .520	ηG^2 = .003
TAP Alertness	SWIS	41.36	(5.93)	42.57	(6.19)	FTime (1,25) = .206			FCondition (1, 25) = 7.768		FTime*Condition (1,25) = .000
Cued reaction time (T)	WLC	47.46	(6.74)	48.77	(6.19)	p = .479	ηG^2 = .011		p = .010	ηG^2 = .207	p = .962	ηG^2 = .000
TAP Go/ NoGo	SWIS	49.27	(10.05)	47.47	(9.49)	FTime (1,27) = .702			FCondition (1, 27) = .266		FTime*Condition (1,27) = .266
Number of errors (T)	WLC	51.00	(7.99)	50.57	(5.94)	p = .410	ηG^2 = .004		p = .610	ηG^2 = .021	p = .610	ηG^2 = .001
TAP Flexibility (T)	SWIS	47.13	(6.68)	52.00	(8.08)	FTime (1,27) = 22.686			FCondition (1, 27) = 8.273		FTime*Condition (1,27) = .409
Overall performance	WLC	55.71	(8.57)	59.43	(7.93)	p = .000		ηG^2 = .074	p = .008	ηG^2 = .217	p = .528	ηG^2 = .001

Table 3. Summary of memory and working memory in both conditions before and after treatment. Note. z = standardized z-value; T = standardized T-Value, VLMT = verbal learning and memory test, D1 = first round of learning

Memory		pre		post		Time effect		Condition effect		Interaction effect (N = 30)
		M	(SD)	M	(SD)
Learning	SWIS	57.61	(7.34)	61.17	(8.56)	FTime (1,29) = 3.627		FCondition (1, 29) = .919		FTime*Condition (1, 29) = .074
	WLC	55.53	(11.06)	58.20	(8.41)	p = .066	ηG^2 = .032	p = .345	ηG^2 = .021	p = .787	ηG^2 = .001
Recall after 30 min	SWIS	13.17	(1.95)	13.61	(2.09)	FTime (1, 29) = .041		FCondition (1, 29) = 1.860		FTime*Condition (1, 29) = 2.025
	WLC	12.53	(2.48)	12.20	(2.65)	p = .840	ηG^2 = .001	p = .182	ηG^2 = .051	p = .165	ηG^2 = .008
Recognition	SWIS	10.76	(2.71)	10.53	(2.87)	FTime (1, 29) = 1.214		FCondition (1, 29) = .405		FTime*Condition (1, 29) = 2.820
	WLC	10.60	(2.64)	11.73	(1.91)	p = .279	ηG^2 = .008	p = .529	ηG^2 = .011	p = .103	ηG^2 = .018
Working Memory
VLMT D1	SWIS	7.44	(2.12)	8.33	(2.17)	FTime (1, 29) = 3.726		FCondition (1, 29) = .133		FTime*Condition (1, 29) = .114
	WLC	7.80	(1.78)	8.40	(2.10)	p = .092	ηG^2 = .033	p = .718	ηG^2 = .002	p = .738	ηG^2 = .001
Digit span forward	SWIS	8.00	(1.50)	8.61	(2.25)	FTime (1, 29) = 2.053		FCondition (1, 29) = .316		FTime*Condition (1, 29) = .316
	WLC	9.67	(1.92)	9.93	(1.53)	p = .162	ηG^2 = .015	p = .578	ηG^2 = .014	p = .578	ηG^2 = .002
Digit span backward	SWIS	6.78	(1.70)	6.83	(1.38)	FTime (1, 29) = .107		FCondition (1, 29) = 3.060		FTime*Condition (1, 29) = .018
	WLC	7.73	(2.22)	7.87	(2.00)	p = .265	ηG^2 = .003	p = .072	ηG^2 = .099	p = .894	ηG^2 = .001

Data availability statement

The data that support the findings of this study are available from the corresponding author, MC, upon reasonable request.