This master thesis focuses on the influence of listening to music during Micro-Breaks on stress reduction. The goal was to gain further information regarding effective stress reduction using Micro-Breaks at work. While the existing studies analyzed either the felt stress under normal conditions or the objective stress under clinical conditions, this study collected data (via measurements and questionnaires) for both the felt stress and the objective stress under normal conditions. To collect the measurements and the answers in the questionnaires, an Android app and corresponding Wear OS app were installed on smartphones and Samsung Galaxy Watch4 devices respectively. This study examined the question whether Micro-Breaks with listening to music can reduce the objective stress and the felt stress more than Micro-Breaks without listening to music. The objective stress was examined using the heart rate and the heart rate variability (SDNN and RMSSD). The raw data were checked, filtered (for example to include only cases where there were values for before, after and during the Micro-Break, deleting "0" values) and then analyzed. The questionnaires were analyzed for changes in the felt stress by taking the answers in the questionnaires and comparing them. The results found in this study were that the values of the heart rate variability (both of the RMSSD and of the SDNN) suggested that the stress level increased during Micro-Breaks with listening to music, while the heart rate decreased and thereby indicated a stress reduction. For the Micro-Breaks without listening to music, the heart rate variability suggested that the stress had slightly increased in the case of the SDNN and slightly decreased in the case of the RMSSD, while the increased heart rate suggested that the stress level had increased. As for the felt stress, the values suggested a slightly better stress reduction during the Micro-Breaks with listening to music than during those without listening to music.