Effects of Sleep Behaviors, Physical Activity, and Dietary Patterns on Mental Health: A Biopsychosocial Model

Abstract

This study aimed to explain how adults living in Tehran experience the individual and interactive effects of sleep behaviors, physical activity, and dietary patterns on mental health within a biopsychosocial framework. A qualitative design using inductive thematic analysis was employed. The participants were 24 adults aged 20–60 years residing in Tehran, Iran, who were recruited through purposive maximum-variation sampling with respect to age, gender, marital status, education, employment, and experience of psychological distress. Data were collected exclusively through individual semi-structured interviews. Interviews lasted between 45 and 75 minutes, were audio-recorded with permission, and were transcribed verbatim. Theoretical and meaning saturation was reached by the twenty-first interview, after which three additional interviews were conducted to confirm the stability and completeness of the categories. Data were organized and analyzed using NVivo 14. The analytic process included repeated familiarization with transcripts, generation of initial codes, comparison and integration of related codes, development of subcategories, construction and review of themes, and definition of final categories. Credibility and dependability were enhanced through participant checking, peer review of coding, documentation of analytic decisions, maximum-variation sampling, and maintenance of an audit trail. Five main categories were identified: “sleep as a regulator of emotional and cognitive functioning,” “physical activity as a means of tension release and restoration of personal agency,” “diet as a determinant of energy, mood, and cognitive stability,” “reciprocal and cumulative lifestyle cycles,” and “the influence of family, occupational, economic, and environmental contexts.” Participants associated regular and restorative sleep, daily movement, and consumption of minimally processed foods with greater calmness, concentration, emotional control, and psychological vitality. Conversely, irregular or insufficient sleep, prolonged inactivity, skipped meals, and frequent consumption of highly processed and sugary foods were perceived to exacerbate fatigue, irritability, anxiety, rumination, and low mood. The three behaviors were rarely experienced independently; rather, they formed reinforcing or deteriorating cycles. Mental health was shaped by dynamic interactions among biological regulation, psychological appraisal and motivation, and social opportunities or constraints. Integrated, gradual, context-sensitive interventions addressing sleep, movement, and nutrition simultaneously may therefore be more feasible and effective than isolated behavioral recommendations.