Optimization of a Digital Self-guided Psychological Intervention for Insomnia: A Randomized Factorial Experiment

In a previous pilot study, a digital self-guided intervention for insomnia showed preliminary positive effects on insomnia symptoms. In order to optimize the digital self-guided format, this study will evaluate the added value of three treatment features on treatment engagement and insomnia symptoms. The participants will be adults with insomnia. The trial will be a 2x2x2 randomized factorial experiment, where the following features/factors will be manipulated: an optimized graphical user interface (yes or no), an adaptive treatment strategy (yes or no), and daily prompts to use the intervention (yes or no). The factorial experiment will create 8 equally large groups (1:1:1:1:1:1:1:1), who will receive the different combinations of features. The main outcome will be the effect on treatment engagement.