Sleep-wake behavior of shift workers using wrist actigraph

The sleep-wake behavior and the effects of aging on the tolerance of night shift were investigated using wrist actigraph for 12 Korean male workers of a continuous full-day three-team three-shift system. The wrist actigraph d ata were obtained for about 21 days (1 shift cycle) for each subject. Durin g night duty, total sleep lime decreased, the number of naps and nap length during on-duty or off-duty periods increased, and the level of activity de creased with increasing age. These results suggest that the tolerance to ni ght shift becomes weaker with increasing age.