Efficacy of Intermittent Exposure to Bright Light for Treating Maladaptation to Night Work on a Counterclockwise Shift Work Rotation

Details

• Personal Author:
  Czeisler, Charles A. ; Duffy JF ; Horowitz TS ; Lammers-van der Holst HM ; Ronda JM ; Wang W ; Wise JC ; Wyatt JK
• Description:
  Objectives Rotating shift work is associated with adverse outcomes due to circadian misalignment, sleep curtailment, work-family conflicts, and other factors. We tested a bright light countermeasure to enhance circadian adaptation on a counterclockwise rotation schedule. Methods Twenty-nine adults (aged 20-40 years; 15 women) participated in a 4-week laboratory simulation with weekly counterclockwise transitions from day, to night, to evening, to day shifts. Each week consisted of five 8-hour workdays including psychomotor vigilance tests, two days off, designated 8-hour sleep episodes every day, and an assessment of circadian melatonin secretion. Participants were randomized to a treatment group (N=14), receiving intermittent bright light during work designed to facilitate circadian adaptation, or a control group (N=15) working in indoor light. Adaptation was measured by how much of the melatonin secretion episode overlapped with scheduled sleep timing. Results On the last night shift, there was a greater overlap between melatonin secretion and scheduled sleep time in the treatment group [mean 4.90, standard deviation (SD) 2.8 hours] compared to the control group (2.62, SD 2.8 hours; P=0.002), with night shift adaptation strongly influenced by baseline melatonin timing (r2= -0.71, P=0.01). While the control group exhibited cognitive deficits on the last night shift, the treatment group's cognitive deficits on the last night and evening shifts were minimized. Conclusions In this laboratory setting, intermittent bright light during work hours enhanced adaptation to night work and subsequent readaptation to evening and day work. Light regimens scheduled to shift circadian timing should be tested in actual shift workers on counterclockwise schedules as a workplace intervention. [Description provided by NIOSH]
• Subjects:
  Circadian Rhythm Endocrine System Lighting Occupational Health Safety Shift Work Schedule Sleep
• Keywords:
  Adaptation Author Keywords: Circadian Phase Circadian Rhythms Hormones Job Rotation Light Amplifiers Melatonin Night Shift Shift Work Shift Worker Shift Workers Sustained Attention Task Performance Work Schedules

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• ISSN:
  0355-3140
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Illinois ; Maryland ; Massachusetts ; OSHA Region 1 ; OSHA Region 3 ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  356-366
• Volume:
  47
• Issue:
  5
• NIOSHTIC Number:
  nn:20063003
• Citation:
  Scand J Work Environ Health 2021 Jul; 47(5):356-366
• Contact Point Address:
  Jeanne F. Duffy, PhD, Division of Sleep and Circadian Disorders, 221 Longwood Avenue, Boston, MA 02115, USA
• Email:
  jduffy@research.bwh.harvard.edu
• CAS Registry Number:
  Melatonin (CAS RN 73-31-4)
• Federal Fiscal Year:
  2021
• Performing Organization:
  Brigham and Women's Hospital, Boston, Massachusetts
• Peer Reviewed:
  True
• Start Date:
  20130901
• Source Full Name:
  Scandinavian Journal of Work, Environment & Health
• End Date:
  20180831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8758473d6b97c193a2b2d9743887c5e277e0397aee9fba11d5ca6d99854974d31b4f0c88967dea4c646fb20ae0aa07886bf1a21695c9e3b8e4247ca996cdced8
• Download URL:
  https://stacks.cdc.gov/view/cdc/226140/cdc_226140_DS1.pdf
• File Type:
  [PDF - 767.49 KB ]