A compromise circadian phase position for permanent night work improves night shift alertness and is compatible with late nighttime sleep on days off

Details

• Personal Author:
  Eastman CI ; Fogg LF ; Smith MR
• Description:
  Introduction: This is the final study in a series designed to produce and maintain a compromise phase position for permanent night work, in which the sleepiest circadian time is delayed out of the night work period and into the first half of daytime sleep, improving night shift alertness and subsequent daytime sleep, but not precluding late nighttime sleep on days off. Methods: Subjects underwent 3 night shifts (23:00-7:00), two days off, 5 more night shifts, and two more days off. During night shifts, an experimental group (n=9) received four 15-minute pulses from light boxes (approximately 4,100 lux, approximately 1,200 uW), interspersed by 45 minutes of room light. The first pulse began at 00:45 and the last ended at 4:00. Subjects wore dark sunglasses (approximately 15% transmission) when outside. Home sleep episodes in darkened bedrooms occurred from 8:30-15:30 after night shifts, 8:30-13:30 after the last night shift in a block, and 3:00-12:00 on days off. Subjects went outside for 15 minutes after awakening to receive a "light brake" to keep them from delaying past the compromise phase position, defined as a dim light melatonin onset (DLMO) of 3:00. A control group (n=10) remained in room light during night shifts, wore lighter sunglasses (approximately 36% transmission), and had unrestricted sleep and outside light exposure. Results: The final DLMO for the experimental group was close to the target compromise phase position, and significantly later than the control group (3:22 +/- 2.0 vs. 23:24 +/- 3.8 h, p < 0.001). Subjects who phase delayed close to the target phase performed better during night shifts. Conclusion: A compromise circadian phase position for permanent night shift work improved performance during night shifts, allowed sufficient sleep during the daytime after night shifts and during the late nighttime on days off, and can be produced by feasible interventions. [Description provided by NIOSH]
• Subjects:
  Circadian Rhythm Men Occupational Health Safety Shift Work Schedule Sleep Sleep Initiation And Maintenance Disorders Women Workplace
• Keywords:
  Circadian-rhythms Humans Psychomotor-function Shift-work Sleep-deprivation Sleep-disorders Work-capability Work-environment Work-performance Workers
• ISSN:
  0161-8105
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Illinois ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  32
• NIOSHTIC Number:
  nn:20045631
• Citation:
  Sleep 2009 Jun; 32(Abstract Suppl):A44
• Federal Fiscal Year:
  2009
• Performing Organization:
  Rush University Medical Center, Chicago, Illinois
• Peer Reviewed:
  False
• Start Date:
  19990930
• Source Full Name:
  Sleep
• Supplement:
  Abstract Supplement
• End Date:
  20090430
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8dd4668e60fcf8d523418ca735c25f7f1b53113f400f9b1feb4c31ce29c8926007485594c3c33c64c00e989e169a582e95013ca5c3aa95a719069eacfcb18ab2
• Download URL:
  https://stacks.cdc.gov/view/cdc/200981/cdc_200981_DS1.pdf
• File Type:
  [PDF - 579.20 KB ]