Affiliations: Department of Hygiene and Public Health, Nippon
Medical School, Tokyo, Japan
Note: [] Address for correspondence: Tomoyuki Kawada, 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: Objective: The effect of shift schedules on the amount of sleep that
workers receive is an important factor in workplace health and safety as well
as the employees' overall quality of life. The objective of this study is to
compare sleep period among workers engaging in each of the three-shift work. Methods and Participants: The amount of sleep (sleep period) that male
workers with rotating shift schedules received was measured using
accelerometers. The mean age of the 16 male workers enrolled in this study was
54.3 years (one standard deviation, 6.7 years). Thirteen participants ranged in
age from 51 to 60 years of age, and the other three participants were 32, 48,
and 50 years old. Work shifts were rotated on a weekly basis and were
categorized into three periods: shift-1 (8:00 to 17:00), shift-2 (15:00 to
23:50), and shift-3 (23:30 to 8:15). Each work week consisted of 5 days. Results: No significant differences were observed in the mean sleep period for
each of the three shifts. However, the sleep periods during shift-1 or shift-2
tended to be longer than that obtained during shift-3. No effect of age on the
length of the sleep period was observed. Conclusions: Rotating shift-work
did not affect the amount of sleep that workers obtained. However, a comparison
with previous study results suggests that morning shifts (starting at 6 AM) and
day shifts (starting at 8 AM) may have different effects on sleep time.
Keywords: Accelerometer, shift work, biological rhythms, automotive industry
