Background: The relationship between total sleep time and activity levels during work before or after sleep in two rotating work shifts was compared.
Method: Monitoring of activity levels using an activity-detecting device in the wrist was conducted in 17 rotating shift workers, who ranged in age from 34 to 55 years. The work shifts, consisting of a morning shift (6:30 to 15:15 hours) and an evening shift (15:15 to 24:00 hours), were rotated on a weekly basis. Partial correlation coefficient was calculated after controlling for age.
Results: The total sleep time after the morning shift was significantly related to the activity count before sleep (r=-0.42) or after sleep (r=-0.36). There was also a significant relationship between total sleep time after the evening shift and the activity count before sleep (r=-0.39) or after sleep (r=-0.32). The mean total sleep time of the subjects for the morning shift was 349 minutes, which was significantly lower than that after the evening shift (382 minutes). In addition, the activity count during the morning shift was significantly higher than that during the evening shift.
Conclusions: The negative relationship between sleep time and activity before or after sleep became clear in shift workers.