Scheduled bright light and darkness to achieve a compromise phase position for permanent night shift work

Details

• Personal Author:
  Eastman C ; Smith M
• Description:
  Introduction: This is the second in a series of studies designed to achieve and maintain a compromise phase position for permanent night shiftwork, in which the sleepiest time of the circadian cycle 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: All subjects underwent 3 consecutive night shifts (23:00- 7:00) followed by two days off. An experimental group (n=9) received five 15-minute light pulses (approximately 3,200 lux, approximately 1,100 uw) beginning at 23:45, interspersed by 45 minutes of room light. They wore sunglasses (approximately 15% transmission) when outside. Sleep in darkened bedrooms was from 8:30-15:30 after the first two night shifts, 8:30-13:30 after the third night shift, 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, a delay of approximately 6 h.A control group (n=12) remained in room light during night shifts, wore sunglasses (approximately 37% transmission), and had unrestricted sleep and outside light exposure. The dim light melatonin profile was collected before and after night shifts and days off to measure the phase shift. Results: Phase delays of the melatonin onset for the experimental group were larger than for the control group (4.2 +/- 0.8 vs 0.9 +/- 1.2 h, p < .001). Conclusion: Our previous study showed a delay of approximately 3 h after two night shifts with bright light. This study found a similar delay of approximately 4 h after three night shifts and two days off. While the compromise position has not yet been reached, a relatively delayed circadian phase was maintained after two days off. More night shifts will be required to achieve the compromise phase position. [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 Light-source Psychomotor-function Shift-work Sleep-deprivation Sleep-disorders Statistical-analysis Work-capability Work-environment Work-performance Workers

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• 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:
  30
• NIOSHTIC Number:
  nn:20046005
• Citation:
  Sleep 2007 Jun; 30(Abstract Suppl):A49-A50
• Federal Fiscal Year:
  2007
• 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-512:7a9811cd079bc5c79da5ab77bbf5121d909bb65c9c6c9ce9c821693bf9fe5058ac521d7a7a399fa475e62aa242989621621f34ad3eec2489bf86aa918932524b
• Download URL:
  https://stacks.cdc.gov/view/cdc/201202/cdc_201202_DS1.pdf
• File Type:
  [PDF - 201.75 KB ]