Many insects regulate diapause—a dormant physiological state—in response to photoperiod, with short day length typically signaling approach of winter and inducing diapause. However, artificial light at night (ALAN), often associated with urbanization, can disrupt these photoperiodic cues and inhibit diapause induction. This review examines the disruption of diapause induction by ALAN, a topic that has only recently attracted considerable attention. First, it summarizes recent empirical studies on ALAN-induced diapause inhibition. Then, it outlines the physiological and molecular genetic mechanisms involved, which remain only partially understood. Next, it discusses potential factors limiting adaptation to ALAN-induced diapause disruption. Finally, this review presents key perspectives from physiological, evolutionary, and applied entomological standpoints to guide future research, emphasizing the need to integrate existing knowledge of diapause regulation with field and laboratory studies to better understand the effects of ALAN and guide mitigation efforts.