RT Journal Article
SR Electronic
T1 Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers
JF Occupational and Environmental Medicine
JO Occup Environ Med
FD BMJ Publishing Group Ltd
SP oemed-2016-103818
DO 10.1136/oemed-2016-103818
A1 Tracey L Sletten
A1 Suzanne Ftouni
A1 Christian L Nicholas
A1 Michelle Magee
A1 Ronald R Grunstein
A1 Sally Ferguson
A1 David J Kennaway
A1 Darren O’Brien
A1 Steven W Lockley
A1 Shantha M W Rajaratnam
YR 2017
UL http://oem.bmj.com/content/early/2017/06/19/oemed-2016-103818.abstract
AB 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, ηp2=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 (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=320845&isReview=true).