Effects of working environments with minimum night lighting on night-shift nurses’ fatigue and sleep, and patient safety

OBJECTIVE: Nurses working rotating shifts often suffer from insomnia or similar disorders because exposure to room lighting at night inhibits melatonin secretion, resulting in a disturbed circadian rhythm. This study investigated whether dark room lighting would be preferable to brighter rooms in terms of (1) fatigue and sleepiness while working, (2) quality of sleep and (3) non-interference with work performance among nurses. METHODS: This study used a non-randomised open-label trial between night shifts using dark (110 lx) and bright (410 lx) room lighting on the desk surface. A total of 20 nurses were enrolled in the trial from November 2015 to February 2016 at a hospital in Japan. All participants worked first with dark room lighting and then with bright room lighting. The participants completed a self-administered questionnaire at enrolment, which was collected this at the end of the intervention. RESULTS: Fatigue and sleepiness were significantly higher in dark room lighting than in bright room conditions (p<0.05). There were no significant differences in sleep quality between the dark and well-lit conditions. We detected no significant differences in the number of reported incidents or accidents comparing the two types of environments. CONCLUSION: Dark room lighting did not ameliorate fatigue and sleepiness during night shifts. Additionally, there was no evidence of improvement in sleep quality among nurses. These findings are important, however, in terms of managing hospital risk.