Background: Sleep disturbances represent a major health burden today, affecting up to one-third of the population worldwide. Computerized cognitive stimulation has been proven as an effective approach in diminishing negative symptomatology and improving the quality of life in a range of medical conditions. Given its nature in enhancing neural networks, such as those involved in stimulus monitoring and inhibitory processes, computerized cognitive stimulation is arising as a potential tool to overcome underlying cognitive deficits found among patients suffering from insomnia. In the current study, we report the results of Phase 1 and Phase 2 clinical trials of a home-based computerized cognitive stimulation program. Methods: The cognitive stimulation intervention followed a home-based approach with online supervision by a psychologist. The training activities were gamified cognitive tasks that had been designed to improve executive functions, with a focus on inhibition skills. The Insomnia Severity Index and the Pittsburgh Sleep Quality Index scales were used as the main assessment measures. Data from the Behavior Rating Inventory of Executive Function, the Beck Depression Inventory, the State-Trait Anxiety Inventory, and the Penn State Worry Questionnaire were also recorded before and after the intervention. During 15 consecutive days, participants performed on alternate days a total of 7 training sessions (each lasting 45 minutes). Results: Twelve patients with clinical insomnia were administered the home-based online cognitive stimulation program. After seven training sessions, mean changes in sleep quality, depressive and anxiety symptoms, worry thoughts, and everyday function were found, with significant improvements in these domains in the full absence of safety issues. Conclusions: In patients with insomnia, cognitive stimulation demonstrated improvements in sleep quality, mood, and cognitive performance over a 15-day protocol. No relevant side effects were reported. The long-term effectiveness of the intervention is still unknown. Clinical Trial Registration: The study protocol has been reviewed and published in ClinicalTrials.gov, assigning it the code NCT05050292 https://clinicaltrials.gov/ct2/show/NCT05050292?term=NCT05050292&draw=2&rank=1.