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Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers

Sletten, T.L., Ftouni, S., Nicholas, C.L., Magee, M., Grunstein, R.R., Ferguson, S., Kennaway, D.J., O'Brien, D., Lockley, S.W. and Rajaratnam, S.M.W. (2017) Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers Occupational and Environmental Medicine, 74 (11). pp. 792-801.

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Objectives Night workers often experience high levels of sleepiness due to misalignment of the sleep-wake cycle from the circadian pacemaker, in addition to acute and chronic sleep loss. Exposure to light, in particular short wavelength light, can improve alertness and neurobehavioural performance. This randomised controlled trial examined the efficacy of blue-enriched polychromatic light to improve alertness and neurobehavioural performance in night workers. Design Participants were 71 night shift workers (42 males; 32.8±10.5 years) who worked at least 6 hours between 22:00 and 08:00 hours. Sleep-wake logs and wrist actigraphy were collected for 1-3 weeks, followed by 48-hour urine collection to measure the circadian 6-sulphatoxymelatonin (aMT6s) rhythm. On the night following at least two consecutive night shifts, workers attended a simulated night shift in the laboratory which included subjective and objective assessments of sleepiness and performance. Workers were randomly assigned for exposure to one of two treatment conditions from 23:00 hours to 07:00 hours: blue-enriched white light (17 000 K, 89 lux; n=36) or standard white light (4000 K, 84 lux; n=35). Results Subjective and objective sleepiness increased during the night shift in both light conditions (p<0.05, η p 2 =0.06-0.31), but no significant effects of light condition were observed. The 17 000 K light, however, did improve subjective sleepiness relative to the 4000 K condition when light exposure coincided with the time of the aMT6s peak (p<0.05, d=0.41-0.60). Conclusion This study suggests that, while blue-enriched light has potential to improve subjective sleepiness in night shift workers, further research is needed in the selection of light properties to maximise the benefits. Trial registration number The Australian New Zealand Clinical Trials Registry ACTRN12610000097044 (;isReview=true). © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Item Type: Article
Authors :
Sletten, T.L.
Ftouni, S.
Nicholas, C.L.
Magee, M.
Grunstein, R.R.
Ferguson, S.
Kennaway, D.J.
O'Brien, D.
Rajaratnam, S.M.W.
Date : 2017
DOI : 10.1136/oemed-2016-103818
Uncontrolled Keywords : alertness, circadian, light, shift work, short-wavelength, 6 hydroxymelatonin o sulfate, 6-sulfatoxymelatonin, melatonin, actimetry, adult, alertness, Article, blue light, circadian rhythm, controlled study, female, human, intervention study, job performance, laboratory, laboratory test, light exposure, major clinical study, male, multicenter study, night work, priority journal, randomized controlled trial, shift worker, simulation, sleep time, sleep waking cycle, somnolence, therapy effect, urine sampling, white light, wrist, young adult, analogs and derivatives, attention, circadian rhythm, light, sleep, Sleep Disorders, Circadian Rhythm, treatment outcome, urine, wakefulness, work schedule, Adult, Attention, Circadian Rhythm, Female, Humans, Light, Male, Melatonin, Sleep, Sleep Disorders, Circadian Rhythm, Treatment Outcome, Wakefulness, Work Schedule Tolerance, Young Adult
Depositing User : Clive Harris
Date Deposited : 17 Jun 2020 01:02
Last Modified : 17 Jun 2020 01:02

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