Study objectives
This study protocol describes a randomised control trial (RCT) examining the efficacy of a newly-developed behaviour change smartphone app, called Holidaily. Holidaily encourages workers to engage in recreational activities before, during and especially after vacations to ideally prolong the beneficial effects of vacationing. We expect levels of the primary outcome, work-related rumination, to be significantly lower 2 weeks post vacation in the intervention versus waitlist-control group. This finding would be important, especially because the constant mental representation of stressors, despite their absence, has been found to extend stress-related physiological activation and, thereby, contribute to the development and maintenance of mental illness. In addition, the hypothesised mechanism — that a change in recreational behaviour causes the effect on work-related rumination — will be investigated via mediation analysis.
Study contributions
Particularly because intervention research on the promotion of recovery after vacations is in its infancy, the present study can contribute to the emerging field in several ways.
First, to the best of our knowledge, this is the first RCT to investigate the efficacy of an app-based intervention encouraging workers to improve and maintain their engagement in recreational activities, with the aim of reducing work-related rumination beyond their vacation into daily working life.
Second, implementing an intervention that promotes recovery behaviours during a period when workers naturally engage in restorative activities may be promising. A systematic review of behaviour theories by Kwasnicka et al. [
122] suggests that initiating behaviour change should occur when an individual’s motivation level is high and their opportunity costs are low. Especially during vacations, it appears that workers can effortlessly create opportunities and are naturally invested, as well as motivated, to engage in recreational activities [
46,
47]. Although vacations seem to offer a promising starting point for implementing a behaviour change intervention, this has not yet been investigated. Our study’s findings may, therefore, contribute by assessing the value of promoting behaviour change maintenance during and beyond workers’ vacations.
Third, so far, only high-intensity interventions — such as personally-guided web-based training — have been investigated and found effective at reducing work-related rumination (i.e., [
61]). Consequently, little is known about app-based interventions’ potential when targeting the reduction of work-related rumination. From a public-health perspective, app-based interventions may be a favourable alternative, as internet-based interventions usually require a laptop computer, which might be inconvenient for workers to access during their vacations. As such, app-based interventions may be more practical, since they can be accessed flexibly and independent of time and place. Our study could, therefore, contribute to this research field by providing insights into the effectiveness of app-based interventions.
Fourth, investigating a potentially underlying mechanism may extend our understanding of the efficacy of low-intensity interventions and health behaviour. Mediation analysis will assess whether change in recreational activities mediates the app’s effect on work-related rumination.
Fifth, exploring whether users’ technical experience with Holidaily contribute to a greater intervention effect could be of great value when designing future app-based interventions. For this reason, moderation analysis will be performed, focusing on Holidaily users’ experiences and the intervention’s effectiveness.
Limitations
Despite the potential contributions of the present study, several limitations must be considered. First, this study’s recruitment strategy involves public media, including Facebook, Instagram, and both radio and TV interviews. Prior to receiving access to Holidaily, the waitlist-control group might become aware of the intervention’s primary aim: to promote the maintenance of recovery behaviours beyond vacations. This could, perhaps, lead to behavioural changes in the waitlist-control group, as well. If this happens, the intervention’s effect could be diffused [
123], indicating only small differences between the two groups at 2 weeks after vacation, leading to underestimation of the app’s true potential. Although public media might reduce the study’s internal validity, external validation of the app might be greatly improved. By broadcasting about the intervention via public media, a potentially wider range of workers could learn about public health measures and may, thus, access health interventions like Holidaily. As a result, the study’s samples may become more heterogenous. Overall, recruiting via public media mimics real-life implementation of health promotion and, therefore, increases the external validity of the current study.
Second, relative to high-intensity interventions and clinical studies, the expected effect size could be considered relatively small. However, this interpretation might be misleading. Clinical studies commonly target mental illnesses like depression and anxiety [
124], where a greater range of improvement is expected. Conversely, this study targets a risk factor in the general working population for which a smaller degree of improvement is anticipated. This has been described as the prevention paradox [
125], stating: “however much it may offer to the community as a whole, it offers little to each participating individual” ([
125], page 1850). Accordingly, health-promotion strategies might only offer a small amount of benefit per individual, but exert a major societal impact by reaching a large population. At a population level, promoting the reduction of work-related rumination may contribute to the prevention of mental illnesses and may, therefore, be beneficial to a larger population. In turn, this also could reduce the costs and time otherwise spent on later treatment for mental illnesses triggered by work-related rumination.
Third, findings from previous observational studies suggest that the beneficial vacation effect experienced by workers is not sustained, but fades out shortly after they return to work, with mental health indicators returning to pre-vacation levels [
46,
47,
56]. Consistent with previous investigators, who usually selected 2 weeks to describe the fading effect, we maintained this timeframe for our primary measurement. Additionally, a 2 week extended follow-up also is included, albeit only to assess stabilisation after the vacation in the intervention group. Further investigations are, therefore, needed. While 2 weeks may be insufficient to verify lasting behavioural changes, they might provide insights into whether the fadeout effect can be reduced. If Holidaily appears to be effective in the short-term only, future studies should also consider potential facilitators and barriers for long-term maintenance.
In the present study, three possible barriers might limit the intervention’s effect to two-weeks. For instance, after their vacation, workers may experience reduced motivation and increased effort to engage in recovery behaviours, due to stresses encountered at work (e.g., work accumulation during their absence; see also [
57]). This might lead to an initial relapse, prompting the fading of the beneficial effect. To overcome such barriers, certain behavioural change techniques, like prompts and self-monitoring, were integrated into this intervention to promote engagement in recovery behaviours during daily working life. It is unclear whether these are appropriate strategies, however. To assess changes and control for potential confounders, for instance, workers’ motivation/engagement is being measured by the Utrecht Work Engagement Scale [
95]
Second, the length of workers’ vacation may play a greater role determining the maintenance of behavioural change than previously anticipated. In one study, as few as 18 or as many as 254 days are required before a newly adopted health behaviour — like improved diet or regular exercise — becomes stable and replaces previously dominant behaviours [
126]. Contrastingly, workers in Germany are legally entitled to a minimum of 24 days of paid vacation. Although the length of workers’ vacation period may be long enough to initiate short-term behavioural change, it might be insufficient for benefits to be maintained long-term. Hence, vacation length will be considered as a confounder.
Third, contrary to studies that suggest that fading of the beneficial vacation effect could be related to barriers hindering behaviour change maintenance, in fact this could be an expression of hedonic adaptation. According to Norrish and Vella-Brodrick [
127], individuals quickly adapt to change, beneficial effects and novel situations. To counteract adaptation, literature highlights the importance of variety [
128]. Although varying recreational activities are integrated into the intervention, perhaps further digital elements — like audio and video features demonstrating specific recovery exercises, or the capacity to upload a video recording from their vacation — could be useful.
Finally, a strong conclusion about the efficacy of the intervention can only be drawn for the primary outcome, the effect of Holidaily on work-related rumination. Results for all secondary outcomes and other variables are descriptive in nature and should therefore be interpreted with caution. However, as interventional research aiming to prolong the beneficial effects of vacation is in its infancy the broad assessment of secondary outcomes should expand the knowledge in this under researched field and guide future research.