Methods:We conducted a randomized crossover study involving registered nurses at a teaching hospital working a two-shift system including the night shift. Participants were instructed to expose themselves to BL for 10 min on workday mornings. Results: A total of 61 participants were enrolled in the present study. Thirty-one participants received BL exposure in the first month, and the other 30 received it in the second month. Significant improvements were noted in the BL periods compared with the non-BL periods for self-assessed sleepiness at 10:00 on day-shift days evaluated using the Karolinska Sleepiness Scale, self-assessment of night sleep for day-shift days using the Visual Analogue Scale and for fatigue assessed using the Checklist Individual Strength Questionnaire. The estimated mean difference for each scale (95% confidence interval) was -0.55 (-0.91, -0.20), 0.37 (0.04, 0.70) and -2.13 (-3.78, -0.48), respectively. Mean response time evaluated using the psychomotor vigilance task test (PVT) showed significant improvement in the BL periods compared with the non-BL periods. No statistically significant differences were observed for sleepiness at 14:00, depression, number of PVT lapses or frequency of perceived adverse events and near misses. Conclusion: Our findings suggest that brief BL exposure on mornings preceding a day shift is effective in improving sleepiness and performance during day-shift work, subjective nighttime sleep on day-shift days, and perceived fatigue for the preceding two weeks in rapidly rotating shift nurses. (J Occup Health 2011; 53: 258-266)

Near miss-based analysis has been recently suggested to be more important in the medical field than focusing on adverse events, as in the industrial field. To validate the utility of near miss-based analysis in the medical fields, we investigated whether or not predictors of near misses and adverse events were similar among nurses at teaching hospitals. Of the 1,860 nurses approached, 1,737 (93.4%) were included in the final analysis. Potential predictors provided for analysis included gender, age, years of nursing experience, frequency of alcohol consumption, work place, ward rotation, frequency of night shifts, sleepiness during work, frequency of feeling unskilled, nurses' job stressors, working conditions, and depression. Variables for multivariate analysis were determined by bivariable analysis. Ordinal logistic analysis showed that predictors of near misses and adverse events were markedly similar. Parameters that were significantly related to both near misses and adverse events were years of experience, frequency of night shifts, internal ward, and time pressure (p<0.05 for all). The present study suggested that there was a negligible difference between choosing near miss-or adverse eventbased analysis when identifying possible causes of adverse events in the medical field.