Comparison of sleep-related cardiac autonomic function between rotating-shift and permanent night-shift workers.

The purpose of this study was to explore whether sleep-related cardiac sympathetic activity is significantly lower in rotating shift workers than in permanent night shift workers, in order to evaluate whether shift work is preferable to permanent night work. Our sample comprised of twelve permanent night shift nurses and twelve rotating three-shift nurses. All female nurses slept in their dormitories, where they were allowed to sleep and wake spontaneously. All sleep parameters were recorded and analyzed using an ambulatory polysomnographic recorder. No significant differences were identified between permanent night shift (PNS) nurses and rotating three-shift (RTS) nurses in terms of basic demographics and sleep patterns. The low frequency (LF) of PNS nurses was significantly higher than that of RTS nurses during both daytime sleep and wakefulness, as was the low-to-high frequency ratio (LF/HF) during both nighttime sleep and wakefulness. PNS nurses also exhibited significantly higher LF and LF/HF during the first to third episode of non-rapid eye movement (NREM1-3) sleep, and the first episode of rapid-eye movement (REM1) sleep. PNS nurses had higher sympathetic activity during nighttime and daytime sleep than did RTS nurses. These results suggest that a rotating three-shift schedule may be preferable to permanent night work in terms of cardiac autonomic regulation.