Evaluation of the Effects of Smoking Cessation on Depression Symptoms, Sleep Quality, Pulmonary Function Test and Body Composition Analysis

Aim: This study aimed to evaluate the impact of smoking cessation on depressive symptoms, sleep quality, pulmonary function, and body composition in individuals attending a smoking cessation clinic and to assess the changes observed three months after quitting.Methods: This prospective, single-center observational study was carried out in individuals aged 18–64 years who presented to a smoking cessation clinic. Data collection included a 67-item face-to-face questionnaire, expiratory carbon monoxide (CO) measurements, anthropometric assessments, and pulmonary function tests (PFTs). At the three-month follow-up, 236 participants who had successfully quit smoking underwent repeat evaluations using the same instruments.Results: The mean age of the participants was 37.37 ± 12.12 years, and 75% were male. The median age at smoking initiation was 16 years (range, 9–42 years), and 59.7% (n=141) were classified as having high or very high nicotine dependence. The age at smoking initiation was progressively lower among younger cohorts (p<0.001). Three months after cessation, the mean Beck Depression Inventory (BDI) scores declined significantly (p<0.001). Pulmonary function tests demonstrated significant improvements in forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and FEV1/FVC ratio, while lung age decreased toward the chronological age (all p<0.001). Pittsburgh Sleep Quality Index (PSQI) scores improved significantly at three months (p<0.001). Body composition analysis revealed statistically significant increases in the body mass index (BMI), body fat percentage (PBF), and basal metabolic rate (BMR) (all p<0.001).Conclusion: Smoking cessation is associated with marked improvements in pulmonary function, mood, and sleep quality. Although modest weight gain may occur, its magnitude is negligible compared to the substantial health benefits of smoking cessation.