BACKGROUND: The increasing integration of mobile technology into daily life has raised concerns about its effects on sleep quality and mental health, particularly among emerging adults. The interplay between evening chronotype, nomophobia (no mobile phone phobia), and FoMO is crucial to understanding these impacts, especially in the digital age. The current study investigated whether nomophobia mediates the relationship between evening chronotype and sleep quality and between chronotype and FoMO with sleep quality in emerging adults. METHODS: A cross-sectional survey was conducted among = 501 emerging adults (Males = 144, Females = 356), aged 18-25 (21.2 ± 1.85 years), after approval from the Institutional Review Board. The participants completed measures of demographic information, sleep quality, FoMO, nomophobia and chronotype. Data were analysed using Jamovi and Statistical Package for the Social Sciences (SPSS). RESULTS: Significant negative associations were found between evening chronotype, FoMO, and sleep quality, indicating that individuals with an evening chronotype and those with higher FoMO tend to experience poorer sleep. Nomophobia significantly mediated the relationships between evening chronotype and sleep quality (Indirect estimate = -0.00896, < .05), and between FoMO and sleep quality (Indirect estimate = 0.0185, < .05), amplifying these negative impacts. CONCLUSION: The study highlights nomophobia's critical role in exacerbating the effects of evening chronotype and FoMO on sleep. Interventions targeting nomophobia and digital habits could improve sleep and mental health among emerging adults.