As health IT has become overloaded with patient information, provider burnout and stress has accelerated. Studies have shown that EHR usage leads to heightened cognitive workload for nurses, and increases in cognitive workload can result in stronger feelings of exhaustion and burnout. We conducted a time motion study in an oncology division to examine the relationships between nurses' perceived workload, stress measured by blood pulse wave (BPw), and their time spent on nursing activities, and to identify stress associated with EHR use. We had a total of 33 observations from 7 nurses. We found that EHR-related stress is associated with nurses' perceived physical demand and frustration. We also found that nurses' perceived workload is a strong predictor of nurses' stress as well as how they spent time with their patients. They also experienced higher perceived mental demand, physical demand, and temporal demand when they were assigned to more patients, regardless of patient acuity. Our study presents a unique data triangulation approach from continuous stress monitoring, perceived workload, and a time motion study.