| Summary: | 博士 === 慈濟大學 === 醫學研究所 === 95 === Study Objectives: The changes of sleep pattern and sleep-related cardiac sympathetic regulations can reflex the probability of the cardiac disease occurrence. This study was to explore the effect of permanent night shift and rotating 3-shift work on sleep-related cardiac autonomic regulation across the first to the fourth non-rapid eye movement sleep (NREM1-4) and rapid eye movement sleep (REM1-4). And the study was to analyze, while controlling for identified covariates, the effects of morningness-eveningness on sleep quality for shift nurses.
Methods: Twenty female nurses were employed on permanent night shift, 3-shift work and regular morning shift at least two- year work experience. All sleep parameters were digitized by an ambulatory polysomnographic recorder. The setting allowed nurses to sleep spontaneously on their own bed and wake up. This design showed that alteration in sleep-related cardiac neuronal regulation for permanent nightshift nurses and rotating 3-shift nurses was compared to that of regular morning shift nurses. In the This analysis included 137 nurses between the ages of 21 - 58. Nurses completed the Horne and Ostberg questionnaire to assess morningness-eveningness and the Pittsburgh Sleep Quality Index (PSQI) questionnaire to measure self-reported sleep quality over the last month. The 18-point Chinese version had a Cronbach’s reliability coefficient of 0.79 overall and 0.86, respectively. This study analyzed correlates of sleep quality by comparing the groups with better or worse sleep quality according to the median of PSQI. Univariate and multivariate analyses were used for the risk factors of worse sleep quality.
Results: 1.Compared to P-daytime, P-nighttime exhibited less accumulated NREM1 time, more accumulated REM1 time, lower EEG ��-power during NREM1 and higher low frequency to high frequency ratio of HRV (LF/HF) during NREM1 and REM1. In addition, compared with the R-nighttime, the EEG ��-power of P-nighttime was significantly lower during NREM1. Also the LF/HF of P-nighttime during NREM1-3, REM1, and that of P-daytime during NREM3 were significantly higher than those of the R-nighttime. 2.Compared with the nighttime sleep of regular morning shift (RM-nighttime), the less accumulated REM1 time of night shift and the EEG δ-power of afternoon shift during NREM1 and NREM2 sleep was significantly prominent, and the low-frequency power (LF) to high-frequency power (HF) ratio (LF/HF) of afternoon shift during NREM1 sleep and that of night shift during NREM3 sleep also had significantly higher value. There was no significant difference between morning shift and RM-nighttime. Although total sleep time of days off was longer, the sleep pattern was similar among different shifts. The HF of days off was significantly higher during NREM1 and REM1 sleep, and the LF/HF of that had lower trend. 3.The result showed that the strongest predictor of sleep quality was morningness-eveningness not the shift schedule or shift pattern for nurses under controlling the variable of age. Greater age and longer years employed in nursing significantly decreased the risk of worse sleep quality. The confounding age factor was properly controlled; evening types working on shifting jobs had higher risk of poor sleep quality compared to morning types.
Conclusions: Permanent nightshift nurses had higher sympathetic activity during sleep compared to that of nighttime sleep in regular morning shift nurses. Rotating 3-shift nurses had different sleep pattern following different shifts. The cardiac sympathetic activity of night shift was significantly higher than regular morning shift, but it could recover during days off. Our results inferred that 2 to 3-year rotating 3-shift would be acceptable, but days off was important for nurses’ cardiac sympathetic regulations. Higher cardiac sympathetic regulations may have a harmful impact on nurses’ sleep patterns in the long term. Morningness-eveningness was the strongest predictor of sleep quality under controlling the variable of age in shift nurses.
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