Novel Circadian Exposure Metrics for Shift Workers

Details

• Personal Author:
  Schernhammer E ; Vetter C
• Description:
  Worker groups studied. Almost 15 million Americans regularly work alternate shifts (1). Observational studies have consistently associated rotating shift work with increases in cancer risk, prompting the WHO in December 2007 to classify night shift work a probable carcinogen - the main operating mechanism being assumed circadian disruption by means of melatonin suppression (2). The broad range of other adverse outcomes affected by working at night implied the necessity for improved tools to comprehensively capture the "exposure" of relevance, i.e. circadian disruption. Future research would benefit from a tool that aids in a more complete description of work schedules and their effects on human cancer risk. Approach. Building on detailed information regarding work hours and sleep in two distinct, prospective cohorts, novel exposure metrics were created that aimed to juxtaposition internal (i.e. preferred sleep timing) with external (i.e. work schedule) clock. In addition to the work and sleep assessments, these two cohorts, Nurses' Health Study 2 (NHS2) and 3 (NHS3), also offer rich information participants' numerous health and lifestyle variables which have been regularly assessed by the biennial mailed questionnaire in NHS2 since 1989, and in NHS3 since its inception in 2010, enabling careful control for potential confounding factors, including use of medications, including antidepressants, anxiolytics, anti-hypertensive and cholesterol-lowering drugs, anti-inflammatory agents, plus health issues including depression, depressive symptoms, hypertension, high cholesterol, diabetes, cardiovascular disease, neurologic diseases, etc. Besides BMI, there is also detailed information on diet and chronotype in both cohorts. Key Findings. Over the past decade, our own work, using data from the Nurses' Health Study cohorts has produced landmark findings and generated provocative novel hypotheses related to the health effects of night work and sleep deprivation: We showed that night shift work increases the risk of a number of different cancers (3-9); we also linked rotating night shift work, through its profound effects on metabolism and weight (i.e. obesity) with other major chronic diseases, including cardiovascular disease (10), metabolic syndrome (11), hypertension (12, 13), stroke (14), endometriosis (15), type 2 diabetes (T2DM) (16, 17). Building on this large body of prior work, in our current project, we were able to successfully demonstrate the utility of two novel and independent exposure metrics capturing circadian strain in night workers, thus providing an important tool in future research, which has been hampered by imprecise exposure assessments leading to bias towards the null in several published studies. How the results relate to improvements for worker safety or health. This project's results will not have any direct impact on the NHS cohorts, but the findings may lead to changes in shift work practice that may benefit women who work rotating night shifts in the future. Ultimately, as outlined in detail in our proposal, the newly developed exposure metrics, once further validated, are geared towards enabling researchers to more fully delineate the adverse health effects of night shift work by also considering the biologically relevant substrate, i.e. circadian disruption in their exposure assessments. [Description provided by NIOSH]
• Subjects:
  Body Weight Circadian Rhythm Cohort Studies Health Personnel Occupational Health Safety Shift Work Schedule Women
• Keywords:
  Biological Rhythms Body Weight Circadian Rhythms Cohort Studies Health Care Workers Hormone Activity Nurses Shift Work 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:
  Massachusetts ; OSHA Region 1
• 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:
  1-13
• NIOSHTIC Number:
  nn:20063864
• NTIS Accession Number:
  PB2022-100452
• 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, R21-OH-011052, 2019 Nov; :1-13
• Contact Point Address:
  Eva Schernhammer, MD, DrPH, Brigham and Women's Hospital, Channing Division of Network Medicine, 181 Longwood Avenue, Boston, MA 02115
• Email:
  eva.schernhammer@channing.harvard.edu
• Federal Fiscal Year:
  2020
• NORA Priority Area:
  Healthcare and Social Assistance
• Performing Organization:
  Brigham and Women's Hospital, Boston, Massachusetts
• Peer Reviewed:
  False
• Start Date:
  20160901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20180831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:da2400ab8ea3c1e28db8e616616622a4af52636f145d0d324fb409e08a85d840ac781765bfb01613ee11dc185dd458268a4567bd36688bedcbabceaba61274c9
• Download URL:
  https://stacks.cdc.gov/view/cdc/219083/cdc_219083_DS1.pdf
• File Type:
  [PDF - 188.51 KB ]