Few studies have examined whether effortful emotion regulation has a protracted impact on subsequent affective appraisal, and even fewer have investigated this effect on a trial-by-trial basis. In this study, we hypothesized that engaging cognitive resources via reappraisal during a trial would result in a subsequent period of increased reactivity on the next trial, as quantified using event-related potentials and oscillations. Forty-eight healthy individuals passively viewed unpleasant and neutral pictures followed by an auditory instruction to either continue viewing normally or reappraise emotional response to pictures. Viewing unpleasant pictures yielded increased late positive potential (LPP) and decreased posterior alpha (8–13 Hz) compared with neutral pictures. A similar pattern was observed on trials that immediately ‘followed’ emotion regulation instructions. Moreover, individuals with increased self-reported depressive symptoms showed greater LPP and alpha modulation following emotion regulation, suggesting that these responses may relate to compromised emotion regulation ability. This study demonstrates that cognitive reappraisal induces subsequent heightened reactivity that may reflect transient resource depletion, and these effects are more pronounced among those with increased depressive symptoms. Interventions that focus on emotion regulation might use these electrocortical markers to track changes in regulatory efficacy.