A former fund manager says he leaves finance to teach mathematics and describes what he experiences in the classroom. According to the account, the first major challenge he encounters is the classroom environment, particularly the level of noise. He reports that the stress from that noise becomes so intense that, after school, he sometimes lies down in a dark room for around 30 minutes each day. He describes this recovery period as a different kind of stress compared with his previous life in finance. The story focuses on his personal transition from fund management to teaching and highlights how adapting to the daily demands and sensory conditions of a classroom affects him physically and mentally. While the sources share the same limited details, they are consistent in stating that the noise in school is his initial trigger and that he uses a daily dark-room rest as a way to cope after work.