<![CDATA[The pervasive integration of social media into the daily lives of Nigerian undergraduates has raised urgent concerns about its implications for academic functioning, yet the pathways through which online social anxieties translate into maladaptive academic behaviours remain insufficiently understood. This study investigated the predictive relationship between fear of missing out (FoMO) and academic procrastination, examining social media addiction and sleep quality as serial mediators within a structural model. Guided by the Interaction of Person-Affect-Cognition-Execution (I-PACE) framework for internet-use disorders, a cross-sectional survey design was employed. A purposive sample of 684 undergraduates from four universities across South-Western Nigeria completed a battery of validated instruments, including the Fear of Missing Out Scale, the Bergen Social Media Addiction Scale, the Pittsburgh Sleep Quality Index, and the Procrastination Assessment Scale-Students. Data were analysed using structural equation modelling with bootstrapped confidence intervals. Results revealed that FoMO did not exert a significant direct effect on academic procrastination (β = .08, p = .11). However, the indirect effect via social media addiction alone was significant (β = .14, p < .001), and the serial indirect effect through social media addiction and sleep quality sequentially was also significant (β = .09, p < .001), indicating full mediation. The hypothesised model accounted for 31% of the variance in academic procrastination. These findings suggest that the anxiety of being socially disconnected drives compulsive social media engagement, which in turn degrades sleep quality and ultimately manifests as academic self-regulatory failure. The study underscores the need for campus-wide digital wellness interventions that address not only time management but also the emotional and physiological mechanisms linking social media use to academic behaviour. University counselling centres in Nigeria should consider incorporating sleep hygiene and cognitive restructuring of online social anxieties into existing academic support programmes.]]>
