Insomnia, particularly maintenance insomnia, is a common yet undertreated sleep disorder. Given the crucial role of slow-wave sleep (SWS) in physiological restoration, we tested modeling-based closed-loop neurostimulation (M-CLNS) targeting the up-phase of slow oscillations via a wearable EEG device. In a double-blind, counterbalanced within-subject design, 21 individuals with self-perceived maintenance insomnia completed multiple nights of stimulation and sham conditions at home. We evaluated M-CLNS performance in phase-targeting and assessed both immediate, stimulus-locked effects and longer-term changes in SWS. Results show reliable targeting of the slow oscillation phase and an immediate enhancement of slow oscillation dynamics. However, due to signal variability across recordings, enduring SWS enhancement could not be conclusively analyzed. These findings suggest that M-CLNS can effectively target slow oscillations and induce short-term improvements in individuals with altered sleep patterns.