This dataset originates from an MSc thesis research project titled "Mental Effect of Distance Learning: A case study of Students of the National Open University of Nigeria." It comprises a comprehensive cross-sectional survey of students at the National Open University of Nigeria (NOUN), the premier open and distance learning institution in Nigeria. The study aimed to assess the mental health status and quality of life of students engaged in distance learning, and to explore the relationships between these factors and various academic, demographic, and lifestyle variables. This is the complete dataset for the study including Digital Friction Scale (DFS) validation (DFS items, learning satisfaction, perceived study efficiency and all variables that was contained in the structured questionnaire used for the study. Methodology and Data Collection: Study Design: Cross-sectional online survey. Population: Students of the National Open University of Nigeria (NOUN). Sample Size: A total of 4612 valid responses were collected from students across various faculties and program levels. Data Collection Period: Data was collected in September 2022. Ethics: Participation was voluntary, anonymous, and based on informed consent. Sampling Method: Two-stage stratified random sampling was utilized to ensure national representativeness and minimized selection bias. The first stage involved stratefication by the six geo-political zones and study centers. The second stage involve the random selection of participants within each identified stratum using established student registries. Instruments/Tools:The survey integrated three key instruments: Demographic and Academic Profile: Capturing information on age, gender, program level, employment status, GPA, study habits, satisfaction, and perceptions of distance learning. Depression, Anxiety, and Stress Scales (DASS-21): A 21-item self-report instrument measuring the emotional states of depression, anxiety, and stress over the previous week. Both raw scores and multiplied severity scores are included. World Health Organization Quality of Life-BREF (WHOQOL-BREF): A 26-item instrument assessing quality of life across four domains: Physical Health, Psychological Health, Social Relationships, and Environmental Quality, plus an overall QoL score. Data Contents and Structure:The dataset file "Integrated MASTER_DASS21_WHOQOL_Original_DataSet" contains one sheet with columns representing: Respondent ID WHOQOL-BREF Domain Scores (Physical_Health, Psychological_Health, Social_Relationships, Environmental_Quality, Overall_QoL) Demographic Variables (Gender, Age_Group, Program_Level, Employment_Status, GPA, Study_Hours, Satisfaction, etc.) DASS-21 Item Responses (D1 to D21) DASS-21 Raw Scores (Dep_raw, Anx_raw, Str_raw) DASS-21 Calculated Severity Scores (Dep_score, Anx_score, Str_score) Potential Reuse:This dataset is valuable for researchers, psychologists, and educational policymakers interested in: The psychological well-being of distance learning students. The relationship between academic stress, quality of life, and mental health. Comparative studies between open university students and traditional university students. Meta-analyses on global student mental health. Developing support interventions for online learners. Usage Notes: The data is fully anonymized. Missing data is coded as N/A. Please refer to the official DASS-21 and WHOQOL-BREF manuals for guidance on interpreting the severity scores and domain scores. Citation:Please cite this dataset if you use it in your work. A recommended citation format is: Effiong Effiong Ndarake, (2025). *Dataset: The Mental Health Impact of Distance Learning - A Cross-Sectional Survey of National Open University of Nigeria (NOUN) Students using DASS-21 and WHOQOL-BREF* [Data set]. Zenodo. Related Thesis:This data supports the findings of the MSc thesis: "Mental Effect of Distance Learning: A Case Study of Students of National Open University of Nigeria"