Lighting Interventions to Reduce Circadian Disruption in Rotating Shift Workers

Details

• Personal Author:
  Figueiro MG
• Description:
  Night work requires inversion of the natural, diurnal human activity-rest cycle and is associated with decreased alertness and some measures of performance, reduced safety, adverse health effects, and chronic disruption of the melatonin cycle that has been associated with increased risk for several major diseases. Previous studies show that red light exposures at night can promote alertness and improve performance while not adversely affecting melatonin secretion and, by extension, circadian rhythms. This ongoing crossover, mixed (within- and between-subjects) design field study tested the efficacy and acceptance of red light delivered to day-shift and night-shift workers using personal light glasses while they were at work. Ninety subjects (mean age 39.6 years [SD = 11.2], 89 females) were recruited from 4 hospitals in Albany, NY; Schenectady, NY; South Bend, IN; and Syracuse, NY. Seventy-eight subjects (49 on day shift, 29 on night shift) completed at least 4 weeks (2 weeks baseline and 2 weeks intervention) of the study's 20-week protocol. Each subject experienced 3 lighting interventions at the eyes: red light (50 lx, 630 nm, the treatment intervention), blue light (50 lx, 460 nm, the positive control intervention), and dim white light (10 lx, 3000 K, the placebo control). During the interventions, subjects underwent visual performance testing, wore actigraphy devices for the recording of personal rest-activity patterns, submitted salivary melatonin and cortisol samples, and provided self-reports of sleepiness, sleep disturbance, and general health. The performance-testing results were mixed, showing some positive effects of red light at the end of the day shift and in the middle of the night shift, when workers are likely to be most tired. Not all of the performance test results were in the expected direction, however. Although no significant effects were noted for most of the objective (actigraphy) rest-activity outcomes, both sleep duration/time lengthened significantly and intradaily variability improved significantly for night-shift workers compared to those on day shift. As hypothesized, only the blue light suppressed melatonin at night, while there was no effect of light (neither blue nor red) on cortisol levels. With respect to the self-reported sleep and general health outcomes, the red light significantly improved sleep quality (along with the blue light, as expected) and sleep disturbance scores compared to the dim white light control. This is the first study to show that red light can be used to improve sleep at home and improve certain types of performance at work without suppressing the hormone melatonin. Melatonin is an antioxidant and its suppression by light at night has been linked to a series of maladies, including increased risk for breast cancer in rotating shift workers. While further study is required to confirm and expand on these results, this study represents an important first step toward demonstrating that red light can be used to significantly improve a broad array of important performance, health, and sleep outcomes among rotating shift workers. [Description provided by NIOSH]
• Subjects:
  Circadian Rhythm Health Personnel Lighting Occupational Health Safety Shift Work Schedule Sleep Sleep Initiation And Maintenance Disorders
• Keywords:
  Circadian Rhythms Health Care Workers Health Effects Hormone Activity Intervention Effectiveness Physical Exercise Shift Work Shift Workers Sleep Deprivation Work Schedules
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  New York ; OSHA Region 2
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-35
• NIOSHTIC Number:
  nn:20063576
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-010668, 2020 Oct; :1-35
• Email:
  mariana.figueiro@mountsinai.org
• Federal Fiscal Year:
  2021
• NORA Priority Area:
  Healthcare and Social Assistance ; Transportation, Warehousing and Utilities
• Performing Organization:
  Rensselaer Polytechnic Institute, Troy, New York
• Peer Reviewed:
  False
• Start Date:
  20150901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20190831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:aac6b21bed4fe94c5d787af52254c8caf24e14f83d9037056d9fca7a8463dc55fcafdd615ea02b961c430acb58bac30e4be2da41724800e0b74ca2f4186d38b5
• Download URL:
  https://stacks.cdc.gov/view/cdc/219078/cdc_219078_DS1.pdf
• File Type:
  [PDF - 1.14 MB ]