Affiliations: Department of Hygiene and Public Health, Nippon
Medical School, Tokyo, Japan
Note: [] Address for correspondence: Tomoyuki Kawada, MD, Department of
Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-Ku,
Tokyo 113-8602, Japan. Tel.: +81 3 3822 2131; Fax: +81 3 5685 3065;
E-mail:kawada@nms.ac.jp
Abstract: 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.
