Smartphone Addiction, Nomophobia, and Text Neck Syndrome: Predictors of Digital Dependence among Young Adults in a Nigerian University Community

Background The increasing reliance on smartphones among university students has raised concerns regarding digital dependence and related musculoskeletal problems, particularly text neck syndrome. Prolonged screen time and sustained forward-head posture have been associated with neck-related functional disability; however, there is limited evidence from African university settings on the combined effects of smartphone addiction and nomophobia on this burden. This study explored patterns of smartphone use and posture behaviors, and assessed the extent to which smartphone addiction and nomophobia predict neck-related functional disability among undergraduate students. Methods A cross-sectional survey was conducted with 399 undergraduate students at the University of Nigeria, Enugu campus. Data were collected using a structured questionnaire and three validated instruments: the Smartphone Addiction Scale–Short Version, the Nomophobia Questionnaire, and the Neck Disability Index. Participants’ smartphone-use patterns and neck flexion postures were assessed. Descriptive statistics, Pearson correlations, and linear regression models were employed, with log-transformed neck disability scores as the dependent variable. Results Students reported high daily smartphone use (mean 6.18 ± 2.39 hours) and predominantly forward-flexed postures (30°-60°). They exhibited moderate–high smartphone addiction (mean 35.60 ± 9.99), moderate nomophobia (mean 95.58 ± 31.57), and mild neck-related functional disability (8.76 ± 6.38). Smartphone addiction correlated positively with nomophobia (r = 0.556, p < 0.001), neck flexion angle (r = 0.326, p < 0.001), and neck-related functional disability (r = 0.249, p < 0.001). In multivariable models, smartphone addiction remained the strongest independent predictor of neck-related functional disability (β ≈ 0.022, p < 0.001), whereas nomophobia showed no independent association after adjustment. Neck flexion angle contributed modestly to disability (β = 0.0039, p = 0.019), while hours of use, break frequency, age, and sex were not significant predictors. Conclusions Undergraduate students demonstrated substantial digital dependence and widespread adoption of ergonomically risky postures. Smartphone addiction emerged a principal behavioral correlate of neck-related functional disability, while nomophobia mainly reflected accompanying psychological features. These findings highlight the need for public health interventions targeting digital dependence and musculoskeletal health in university settings. Strategies promoting healthier posture, regular breaks, and moderated smartphone use may help reduce the musculoskeletal burden associated with text neck syndrome in university populations.