CONTEXT: Access to social network sites (SNS) is commonplace, especially among young people globally. Cumulatively, long duration of daily exposure may be having effects on psychological health outcomes, including increased and in some cases, decreased risk of depression and anxiety. Despite these potential effects, there is a paucity of literature on patterns and effects of exposure to social media, especially in developing countries where regular mental health screening is generally unavailable. AIM: This study aims to assess the psychological effects of Internet/social media usage among undergraduates in Calabar. SETTINGS AND DESIGN: A descriptive cross-sectional study conducted in the University of Calabar, Nigeria. METHODOLOGY: Multi-staged sampling technique was used to recruit equal proportions of the undergraduate students from five selected Faculties in the University. Internet Addiction Test and General Health Questionnaire-28 were used to measure addiction to Internet and psychological health status of the respondents, respectively. Socio-demographic questionnaire was used to obtain information on demographic and social media characteristics of the respondents. STATISTICAL ANALYSIS: Chi-square and independent t-test were used as inferential statistics, with P value set at 0.05. RESULTS: Four hundred and eighteen (418) respondents completed the questionnaires. The mean age was 21.5 ± 3.6 years. Male:female ratio was 1:0.99. WhatsApp (59.8%) was the most commonly visited social media platform, whereas entertainment (52.2%) was the most common reason for social media use. About one-fifth (20.1%) had moderate-to-severe forms of Internet addiction, whereas one-third (33.1%) were psychologically distressed. Psychological distress was found to be significantly more common among respondents with mild/none, compared with those with moderate-to-severe forms of Internet addiction (P = 0.00). Respondents with moderate-to-severe forms of Internet addiction had significantly lower mean depression and anxiety scores compared with those with mild or no form of addiction (P = 0.00). CONCLUSIONS: There is high degree of psychological distress among students, and this was found to be more common among those that were less/not addicted to SNS. Specifically, high degree of Internet addiction may be protecting against the increased risk of depression and anxiety. The implications of these findings on youth counselling and the prevention of mental illnesses in developing countries are discussed in this article.