From the 12 participants participating in the iCBT‑I prevention self-learning training, feedback data regarding online training is available, whereas post-measurements of 9 participants were assessed. In addition, participants returned the sleep-related questionnaire (PSQI) and other questionnaires as mental health-related information (WHO-5).

One of the main objectives was to evaluate the acceptance of online iCBT‑I prevention training from the participants’ view. Therefore, in the following sections, we first describe the results of the OSTA and the OSTF regarding acceptance of the prevention training but also results of qualitative research.

For outcomes concerning sleep and mental health we present pre- and postmeasurement data of participants who returned the postmeasurement questionnaires (n = 9).

Acceptance

To measure acceptance, participants rated all topics of the online self-learn training with the OSTA on a five-point Likert scale. In sum, all participants rated the information given in the modules as helpful. In all, 33% rated the material as very helpful. In addition, we received 24 module-feedback questionnaires (Tables 3 and 4).

Table 3 Questions of Online Sleep Prevention and Treatment Acceptance questionnaire (OSTA) over all modulesTable 4 Means of all modules based on Online Sleep Prevention and Treatment Acceptance questionnaire (OSTA) questionnaires

In addition to the contents of the training, we also evaluated the implemented videos in detail. Most of the participants liked the videos. Detailed results regarding the OSTF are presented in Table 5.

Table 5 Online Sleep Treatment Feedback Questionnaire (OSTF). “How useful was [part of program] for you?”

Overall evaluation of the training was conducted with OSTE. In Table 6 the results are presented in detail.

Table 6 Online Sleep Treatment Feedback Questionnaire (OSTF)Qualitative feedback (open answer format)Course content Content aspects (CA).

Regarding information transfer, the participants rated the program as understandable and remarked positively that the information directly addressed the matter and the information parts were appropriate in length. Although some of the content was already known, there were parts that participants reported as being of special interest. Beside factors like everyday mindfulness, flow and individual differences in sleep behavior, information on factors influencing sleep, “there are things you can’t change regarding sleep […] That is reassuring. But there are also some things you can change.” was highlighted multiple times as being very valuable.

Exercises (EX).

In the answers to the evaluations questionnaires there was a lot of positive feedback regarding the exercises. Nine comments were given about how great the various exercises were, “Breathing exercise is great, just like a prescription”. However, there were some remarks about the wording and illustration that could be improved for better clarity. The integratability into day-to-day life was praised by five participants, “The breathing exercise is easy to integrate into everyday life”, as well as the implementability, “Easy to implement”.

Implementation of the course Technical implementation of the course (TI).

Concerning the technical implementation there were positive comments, especially mentioned were the LernraumPlus interface and the general structure of the program. A suggestion for improvement was to use more variety in the form the content is presented. Particularly more audio options would be appreciated, since these would offer more flexibility to use the program in daily life and get away from the screen. It was remarked that the used online tools need practice and that one has to get used to using them, but that they also work quite well and hold certain benefits.

Course procedure and structure (PS).

The overall structure of the program was received very well. Five comments emphasized that the procedure of having certain main topics, which order is chosen freely is a good concept, “Very good that you can swap the order between main topics”. Some participants suggested to offer additional individual consulting appointments to deal with individual questions and topics, if that would be feasible.

Feedback on the course material (CM).

This category got most feedback in comparison with the others (33 comments were in the category CM). Eight comments stated that the drawings were pretty and descriptive: “the small drawings are pretty and visually emphasize what is being said”. The way of speaking yielded mixed reactions: five comments liked the calm style that was used (“I could follow the video very well, it was pleasantly spoken, it took the pressure out overall”) but two comments did not see that equally well (“With the speaking text, I would like to see a more positive mood conveyed”). The background noise, which occurred in some recordings, was disliked especially during the exercise: “[…] background noise on the recording distracted me and it was not very soothingly spoken.” The visibility of the trainers in the course videos was also received variably. While three comments rated this as a nice and relatable feature, in two comments it was found distracting: “With the Panopto video, I would have liked to have only the audio and not have the speaker in the picture. That was distracting to me”. One comment stated that differing speakers helped to maintain attention throughout the course.

Effects on participants (EP)

There were some quite encouraging effects as experiencing better sleep afterwards. Not all parts were helpful though, exercises were tried but did not have an effect: “I already use such mindfulness exercises, but I doubt that they help me. I use them at night when I can’t sleep. Often they do not help”. Sleep was noticeably improved through the awareness that sleep interruptions in the night do not have to be a big issue to worry about because worrying itself is a problem.

Other comments (OC)

Participants described that they had various differing sleeping conditions which were not completely included in the questionnaires. This included sharing of bed with snoring partners half of the weekly nights and changing apartments on the weekend: “My sleeping situation is pretty much as stated in the questionnaire (alone) half the time, the other half of the time I sleep in a bed with my partner.”. Mindfulness was described as a difficult concept to work with in two comments because of exaggerated claims which were encountered in contexts other than those in the program. An especially reflective handling of the term was suggested. Three comments stated that they would have liked further integration with other resources, e.g., courses, online literature or links (Table 7).

Table 7 Overview of qualitative feedbackFirst effects

Besides feasibility, acceptance and adherence we also evaluated the sleep-related effect in this pilot study. Therefore, sleep-related feedback was assessed by PSQI. In addition, mental health will be reported, pre–post data will be presented.

Overall, 56% of the participants slept better after the training according to self-report with a significant clinical change (Fig. 1). On average, participants experienced better overall sleep quality (PSQI scores) after the program (M = 7.44, SD = 4.13), than before the program (M = 10.33, SD = 3.97). This difference, −2.89, BCa 95% CI [−4.55, −1.22], was significant t(8) = −3.0, p = 0.017, and represented a large effect, d = 2.89.

Fig. 1

Changes of Pittsburgh Sleep Quality Index (PSQI) scores prior to and after training

On average, participants slept longer after the training (M = 0.67, SD = 1.11), than before the program (M = 1.67, SD = 0.87). This difference, −1.0, BCa 95% CI [−1.67, −0.33], was significant t(8) = 2.68, p = 0.028, and represented a large effect, d = 1.12.

On average, participants experienced no change in sleep quality due to bad dreams (“had bad dreams”): after the program (M = 1.67, SD = 1) was the same as before the program (M = 1.67, SD = 1). However, the change −0.00, BCa 95% CI [−0.33, 0.33], was not significant (t(8) = 0, p = 1.).

Insomnia symptoms

Prior to training, 56% participants reported insomnia symptoms as prolonged sleep onset latency of more than 30 min, or nocturnal wakenings, and daytime impairment as tiredness.

Insomia symptoms were reduced as participants fell asleep faster afterwards (M = 1.56, SD = 0.73) than before training (M = 2.0, SD = 1.0). The enhancement, −0.44, BCa 95% CI [−0.78, −0.11], was significant t(8) = −2.53, p = 0.035, with a medium-sized effect, d = 0.53. Furthermore, insomnia symptoms as prolonged sleep onset latency (more than 30 min) was reduced after training (M = 2.44, SD = 0.73) than before the program (M = 3.11, SD = 0.93). This difference, −0.67, BCa 95% CI [−1.11, 0.22], was also significant t(8) = 2.82, p = 0.022, with a medium effect size, d = 0.71. In addition, problems sleeping through the night also improved after the program (M = 3.11, SD = 1.27), in contrast to before the program (M = 3.33, SD = 1.11). However, this difference, −0.22, BCa 95% CI [−0.89, 0.44], failed to reach significance t(8) = −0.61, p = 0.56. In addition, daytime tiredness decreased from M = 1.44 (SD = 0.73) to PM = 1.22 (SD = 0.67) after training. Furthermore, participants reported improved subjective sleep quality (PSQI scores) after training (M = 1.22, SD = 0.44) than before (M = 1.89, SD = 0.78). This difference, −0.67, BCa 95% CI [−0.89, −0.33], was significant t(8) = −4.00, p = 0.004, with a medium-sized effect, d = 0.5.

The mental health score (WHO‑5 score) was M = 9.89 (SD = 4.01) prior to online training and M = 10.33 (SD = 3.36) after training. Values less than 13 may be an indicator for depression. A higher value indicates greater well-being (maximum 25).