INTRODUCTION: The global rise in smartphone usage, especially among young adults (18-25 years), has prompted alarm regarding its influence on the sleep health. Smartphone addiction through an irresistible urge and excessive use has been implicated in various behavioural and psychological disturbances. Sleep, an important predictor of well-being, is particularly susceptible to excessive its exposure; but how much and how consistently is unclear. This study aimed to systematically review and quantitatively synthesize the evidence on the association between smartphone addiction and sleep disruption amongst young people.

CONTENT: A systematic search of electronic databases (SpringerLink, ScienceDirect, PubMed, and Google Scholar) was conducted to identify observational studies "smartphone addiction" and "sleep quality" among this group (18-25 years). Screening was done with the help of Rayyan AI, and the included studies were evaluated using JBI appraisal tool. Total of 68 articles were included for systematic review, of which 63 contributed to the meta-analysis. Findings were synthesized narratively, and quantitative effect size data were extracted to enable meta-analytic assessment. Narrative synthesis consistently showed that higher levels of smartphone overuse were linked to poorer sleep outcomes, including delayed onset of sleep, shorter sleep period, poorer global sleep quality, and greater daytime dysfunction. The pooled analysis found a moderate positive correlation (r=0.38, 95 % CI: 0.31-0.48, p<0.001) between smartphone addiction and poor sleep quality. There was a significant variation observed across studies (I=99.25 %). Publication bias assessments using the Egger's regression, Begg's test and trim-and-fill analysis showed no significant evidence of publication bias.

SUMMARY: The findings provide strong and consistent evidence that young adults' poor sleep quality is moderately correlated with smartphone addiction. Although most available evidence is based on cross-sectional studies and self-reported measures, the results highlight problematic use of smartphone as an important, potentially changeable behavioural risk factor for sleep disturbance.

OUTLOOK: Future research should prioritize longitudinal study designs, objective measures of smartphone use and sleep, and intervention studies to clarify causal pathways and identify effective strategies for improving sleep health among young adults.