NLM Director’s Comments Transcript
Diabetes, Obesity & the Night Shift: 03/05/2012

Greetings from the National Library of Medicine and MedlinePlus.gov
Regards to all our listeners!
I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.
Here is what's new this week in MedlinePlus.

Nurses who work the night shift experience a significantly higher risk of obesity and type 2 diabetes, finds a comprehensive study recently published in PLOS Medicine.
The study of 180,000 women found nurses who self-reported they worked rotating night shifts were five to 58 percent more likely to develop type 2 diabetes than nurses who worked daylight hours. Among the participants (who were followed for 20 years), the authors found the duration of time spent on a rotating night shift increased the risk nurses would develop type 2 diabetes.
Similarly, the findings suggest the number of years nurses work rotating night shifts is associated with a higher risk of weight gain and obesity.
In contrast to previous research, the findings suggest an increased risk of type 2 diabetes is not additionally associated with rotating night work and Body Mass Index, a number calculated from a person’s body weight and height.
The authors add the statistical relationships among rotating shift work, type 2 diabetes, and obesity remained robust after the researchers controlled for other possible clinical and lifestyle predictors of type 2 diabetes and obesity, such as smoking, physical activity, and diet quality.
Overall, the study’s four authors write (and we quote): ‘Our current analysis provides compelling evidence that an extended period of rotating night shift work is associated with a moderately increased risk of type 2 diabetes’ (end of quote).
The study yields the most comprehensive information about the health impacts of rotating shift work to date because its findings are derived from a broader women’s health assessment, the Nurses’ Health Study. The Nurses’ Health Study is partially sponsored by the National Heart, Lung, and Blood Institute and several Massachusetts medical institutions, including Brigham and Women’s Hospital and Harvard Medical School. One group of the participants selected for the current study enrolled in the Nurses’ Health Study at ages 42-67 and were followed from 1988-2008. A second group enrolled at ages 25-42 and were followed from 1989-2007.
Incidentally, you can find many research reports derived from the Nurses’ Health Study simply by typing ‘Nurses Health Study’ in the search box on MedlinePlus.gov’s home page.
In addition to the statistical associations raised by the findings, the study’s four authors discuss (but do not assess) whether an underlying biomedical explanation clarifies why night work impacts type 2 diabetes and obesity. The authors note nurses who have rotating night shifts experience interruptions to their circadian rhythms. The authors add some biological processes regulated by circadian rhythms include sleep-wake cycles, body temperature, energy metabolism, cell cycles, and hormone secretion.
The authors conclude (and we quote): ‘because a large proportion of the working population is involved in some kind of permanent night and rotating night shift work our study has potential public health significance’ (end of quote).
Indeed, an accompanying editorial (written by PLOS Medicine’s editors) adds the study’s findings provide new insights about the welfare of nurses as well as occupational health. PLOS’ editors write (and we quote): ‘the authors draw attention to some intriguing possibilities for where the field of occupational health might now fruitfully focus its efforts’ (end of quote).
Meanwhile, a website provided by the National Institute for Occupational Safety and Health (within the ‘start here’ section of MedlinePlus.gov’s occupational health topic page) provides a helpful introduction to how work sometimes is linked to a range of diseases and injuries. A video about shift work and improving sleep (from Harvard Medical School) is available in the ‘videos’ section of MedlinePlus.gov’s occupational health health topic page
MedlinePlus.gov’s occupational health topic page also contains a link to women’s safety and health issues (provided by the National Institute for Occupational Safety and Health) that is available within the ‘women’ section.
MedlinePlus.gov’s occupational health topic page contains links to the latest pertinent journal research articles, which are available in the ‘journal articles’ section. Links to related clinical trials that may be occurring in your area are available in the ‘clinical trials’ section. From the occupational health health topic page, you can sign up to receive email updates with links to new information as it becomes available on MedlinePlus.
To find MedlinePlus.gov’s occupational health topic page, please type ‘occupational health’ in the search box on MedlinePlus.gov’s home page, then, click on ‘occupational health (National Library of Medicine).’
Other related health topic pages within MedlinePlus.gov include: safety issues, wellness and lifestyle, plus farm health and safety.
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A disclaimer – the information presented in this program should not replace the medical advice of your physician. You should not use this information to diagnose or treat any disease without first consulting with your physician or other health care provider. I want to take the opportunity to wish you a very happy holiday season and a healthy New Year. The National Library of Medicine and the 'Director's Comments' podcast staff, including Dr. Lindberg, appreciate your interest and company – and we hope to find new ways to serve you in 2012.
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