Stress is the feeling of emotional strain in response to a perceived threat that disturbs the homeostasis and affects our health and well-being. Short-term stress has some beneficial effects such as improving alertness and performance and boosting memory, but prolonged stress responses can have deleterious effects on human health, including tissue damage and disease. Thus regulating stress levels is important for dealing with difficult situations to mitigate negative impacts. Prevailing approaches to treating stress have some limitations and drawbacks. Slow breathing/Resonant frequency breathing or HRV biofeedback and Music Therapy are some of the widely used methods for dealing with stress and anxiety. These methods are thought to stimulate the vagus nerve that promotes autonomic balance and hence reduce symptoms of stress. The current study investigated the effects of relaxing music and Slow breathing/Resonance frequency breathing on heart rate variability and respiration as well as on subjective measures of perceived stress. Although relaxing techniques are often administered in group classes, research studies in groups are rare. To our knowledge, this is the first study to investigate the effects of music listening and slow breathing in reducing stress evoked by watching a stressful movie in a group setting. The study sought to evaluate the effectiveness of the aforementioned interventions in reducing stress, measured by psychophysiological and self-report measures. Thirty-two participants were recruited and randomly assigned to two groups (Music, Breathing). We hypothesized that after watching the stressful movie, the Breathing group would show greater physiological and self-report changes marking greater stress reduction compared to the Music group. Results indicated that slow Breathing affected perceived stress as well as HRV, whereas Music affected perceived stress, but had no significant effect on HRV. Also, results indicated that Slow Breathing and not Music reduced the complexity of heart and respiration signals. Moreover, the study found that respiration and heart rhythm synchronized maximally during slow breathing. The results suggest that the interventions studied in this research can be used as an effective stress reduction tool in a group setting. / Thesis / Master of Science (MSc)