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

Tracey L. Sletten, Suzanne Ftouni, Christian L Nicholas, Michelle Magee, Ronald R Grunstein, Sally Ferguson, David J Kennaway, Darren O'Brien, Steven W Lockley, Shantha M W Rajaratnam

Research output: Contribution to journalArticleResearchpeer-review

Abstract

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).

Original languageEnglish
Pages (from-to)792-801
Number of pages10
JournalOccupational and Environmental Medicine
Volume74
Issue number11
DOIs
Publication statusPublished - 19 Jun 2017

Keywords

  • Alertness
  • Circadian
  • Light
  • Shift work
  • Short-wavelength

Cite this

Sletten, Tracey L. ; Ftouni, Suzanne ; Nicholas, Christian L ; Magee, Michelle ; Grunstein, Ronald R ; Ferguson, Sally ; Kennaway, David J ; O'Brien, Darren ; Lockley, Steven W ; Rajaratnam, Shantha M W . / Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers. In: Occupational and Environmental Medicine. 2017 ; Vol. 74, No. 11. pp. 792-801.
@article{2b7e02ca814f490fa03ec3fb5b7bfa0d,
title = "Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers",
abstract = "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).",
keywords = "Alertness, Circadian, Light, Shift work, Short-wavelength",
author = "Sletten, {Tracey L.} and Suzanne Ftouni and Nicholas, {Christian L} and Michelle Magee and Grunstein, {Ronald R} and Sally Ferguson and Kennaway, {David J} and Darren O'Brien and Lockley, {Steven W} and Rajaratnam, {Shantha M W}",
year = "2017",
month = "6",
day = "19",
doi = "10.1136/oemed-2016-103818",
language = "English",
volume = "74",
pages = "792--801",
journal = "Occupational and Environmental Medicine",
issn = "1351-0711",
publisher = "BMJ Publishing Group",
number = "11",

}

Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers. / Sletten, Tracey L.; Ftouni, Suzanne; Nicholas, Christian L; Magee, Michelle; Grunstein, Ronald R; Ferguson, Sally; Kennaway, David J; O'Brien, Darren; Lockley, Steven W; Rajaratnam, Shantha M W .

In: Occupational and Environmental Medicine, Vol. 74, No. 11, 19.06.2017, p. 792-801.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Randomised controlled trial of the efficacy of a blue-enriched light intervention to improve alertness and performance in night shift workers

AU - Sletten, Tracey L.

AU - Ftouni, Suzanne

AU - Nicholas, Christian L

AU - Magee, Michelle

AU - Grunstein, Ronald R

AU - Ferguson, Sally

AU - Kennaway, David J

AU - O'Brien, Darren

AU - Lockley, Steven W

AU - Rajaratnam, Shantha M W

PY - 2017/6/19

Y1 - 2017/6/19

N2 - 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).

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).

KW - Alertness

KW - Circadian

KW - Light

KW - Shift work

KW - Short-wavelength

UR - http://www.scopus.com/inward/record.url?scp=85026634936&partnerID=8YFLogxK

U2 - 10.1136/oemed-2016-103818

DO - 10.1136/oemed-2016-103818

M3 - Article

VL - 74

SP - 792

EP - 801

JO - Occupational and Environmental Medicine

JF - Occupational and Environmental Medicine

SN - 1351-0711

IS - 11

ER -