Purpose <p>Attentional lapses are often attributed to fatigue and poor sleep. The present study examined whether boredom proneness contributes to attention-related cognitive errors among university students and whether sleep quality mediates this relationship.</p> Methods <p>Data were gathered through a cross-sectional survey involving 843 university students in the 18–25 age range. Participants completed the Boredom Proneness Scale (BPS), Pittsburgh Sleep Quality Index (PSQI) and Attention-Related Cognitive Errors Scale (ARCES). Data were analysed using IBM SPSS (version 26). Mediation was tested through the PROCESS macro (Model 4).</p> Results <p>Boredom proneness showed a strong positive association with attention-related cognitive errors (r = 0.749, <i>p</i> &lt; 0.001) and a moderate relationship with poorer sleep quality (r = 0.381, <i>p</i> &lt; .001). Poorer sleep quality was also positively related to cognitive errors (r = 0.376, <i>p</i> &lt; 0.001). Mediation analysis indicated that sleep quality significantly mediated the relationship between boredom proneness and cognitive errors. However, the indirect effect accounted for only 5.42% of the total effect, whereas the direct pathway explained the majority of the association.</p> Conclusion <p>These findings show that trait boredom is strongly associated with everyday attentional failures. However, sleep quality only partially mediated this relationship. Therefore, interventions focusing on improving attentional functioning in university populations should consider boredom and enhancing cognitive engagement.</p>