Bright environmental light improves the sleepiness of nightshift ICU nurses

BackgroundShift work can disturb circadian homeostasis and result in fatigue, excessive sleepiness, and reduced quality of life. Light therapy has been shown to impart positive effects in night shift workers. We sought to determine whether or not prolonged exposure to bright light during a night shift reduces sleepiness and enhances psychomotor performance among ICU nurses.MethodsThis is a single-center randomized, crossover clinical trial at a surgical trauma ICU. ICU nurses working a night shift were exposed to a 10-h period of high illuminance (1500-2000lx) white light compared to standard ambient fluorescent lighting of the hospital. They then completed the Stanford Sleepiness Scale and the Psychomotor Vigilance Test. The primary and secondary endpoints were analyzed using the paired t test. A pvalue <0.05 was considered significant.ResultsA total of 43 matched pairs completed both lighting exposures and were analyzed. When exposed to high illuminance lighting subjects experienced reduced sleepiness scores on the Stanford Sleepiness Scale than when exposed to standard hospital lighting: mean (sem) 2.6 (0.2) vs. 3.0 (0.2), p=0.03. However, they committed more psychomotor errors: 2.3 (0.2) vs. 1.7 (0.2), p=0.03.ConclusionsA bright lighting environment for ICU nurses working the night shift reduces sleepiness but increases the number of psychomotor errors.Trial registrationClinicalTrials.gov, NCT03331822. Retrospectively registered on 6 November 2017.