Nurses' workload associated with 16-h night shifts on the 2-shift system. I: Comparison with the 3-shift system.

To assess nurses' workload with 16-h night shifts on a 2-shift system, we investigated the differences between workloads with each shift on the 2- and 3-shift systems with questionnaires on subjective symptoms and measuring heart rate and physical activity. It was found that the 2-shift nurses during the 16-h night shifts complained of fatigue less frequently and showed general decreases in heart rate and physical activity compared with the 3-shift nurses during 8-h evening and night shifts. The results suggest that a 2-h nap, an increase of staff, and a day off may reduce the nurses' workload when they have 16-h night shifts.