Effects of nocturnal shiftwork on mood states of student nurses

Daily mood changes were monitored over successive 24-h periods using the Profile of Mood States (POMS) (3) to assess the effect of nocturnal shiftwork on mood. Twenty-three student nurses, age range 19-24 years, were studied throughout their first experience of nocturnal shiftwork. The POMS was administered over four complete solar days during a 12-week period that included an 8-week block of night work. Five POMS dimensions displayed circadian rhythmicity: vigor-activity; fatigue-inertia; confusion-bewilderment; friendliness; and total-mood-disturbance. These five dimensions were sensitive to changes in living patterns, showing phase shifts in their circadian rhythms when subjects alternated between diurnal and nocturnal living patterns. The dimensions were also observed to be sensitive to adjustment to two different nocturnal shiftwork schedules. The subjects who worked "four on, three off" showed similar phase shifts to the subjects who worked "eight on, seven off," suggesting that mood adjustment takes place by the fourth night of a rotation of nights. The "commitment" of the students to the nocturnal living pattern was thought to have a bearing on the adaptation of the students to the nocturnal shifts, as regards mood.