Table of contents
- See also Vitamin D Life
- See also shift-work and Vitamin D/health on the web
- Hypotheses for mechanisms linking shiftwork and cancer.
- Adverse Metabolic Consequences in Humans of Prolonged Sleep Restriction Combined with Circadian Disruption
- Article in Kurzweilai.net which read the above study and reported on it
- The following found NO association of low vitamin D in a few shift workers where their shifts were constantly rotating thus having access to middle-of-the-day sunshine many times per month
- Long-term shift workers 48% more likely to get Breast Cancer - Vit D and Melatonin suspected - Review Dec 2015
See also Vitamin D Life
- Shift workers 2X more likely to get COVID-19 (low Vitamin D) - Dec 2020
- Reduced Vitamin D status in rotating shift workers in the summer and fall – April 2020
- Shift workers have low vitamin D, poorer sleep, and are more depressed – March 2019
- Employers should give night shift workers free vitamin D – GMB Union June 2019
- Miscarriage 32 percent more likely if work night shift (probably low Vitamin D) – April 2019
- Shiftworkers and Indoor Workers have lower Vitamin D levels – review of 10 studies Sept 2018
- Employers should give night shift workers free vitamin D – GMB Union June 2019
- Night cleaners deficient in vitamin D - Nov 2015
- 40 percent lower vitamin D level if work other shifts (Italy) – June 2015
- Night shift workers far more likely to have low vitamin D levels – May 2016
- Allergies and low vitamin D strongly associated with night shift bakers– Sept 2014
- Working other than dayshift reduces vitamin D levels and Bone Mineral Density and increases bone pain – Aug 2013
- Shift workers 23 percent more likely to have cardiovascular events – meta-analysis July 2012
- Shift work increases breast cancer risk by 22 percent (Vitamin D is 1 of 5 possible ways) – Oct 2013
- US truckers die 16 years earlier - partially due to vitamin D deficiency - Feb 2011 which has the following diagram
See also shift-work and Vitamin D/health on the web
- Are Shiftwork and Indoor Work Related to D3 Vitamin Deficiency? A Systematic Review of Current Evidences - 2018 DOI: 10.1155/2018/8468742 Reviw of 10 studies: YES FREE PDF
- MS and shiftwork 2011
- Study of shiftwork then later getting MS
- Breast cancer risk 'doubles from working nights' July 2013
- Working Nights May Raise Diabetes Risk NYT Feb 2018
- 47,000 workers,"those who worked irregular shifts with frequent night shifts were 44 percent more likely to have Type 2 diabetes"
- no mention of Vitamin D in the abstract. FREE PDF https://doi.org/10.2337/dc17-1933
Hypotheses for mechanisms linking shiftwork and cancer.
Med Hypotheses. 2011 Jun 30
Fritschi L, Glass DC, Heyworth JS, Aronson K, Girschik J, Boyle T, Grundy A, Erren TC.
Western Australian Institute for Medical Research, The University of Western Australia, Perth, Western Australia, Australia.
Shift work has been associated with various adverse health outcomes. In particular, there has been a recent flourish in investigating potential cancer risk associated with working night shifts and other shift schedules. Epidemiologic studies have revealed generally weak associations due to several methodological challenges such as lack of standard classifications of shift or night work. The field also has been hindered by a lack of clarity about the possible mechanisms by which shiftwork could have an effect on cancer risk.
One possible mechanism is reduced production of melatonin caused by exposure to light at night. Although there is a growing body of evidence that provides some support for this mechanism, several other mechanisms also make sense from a biological point of view.
Further, the relatively weak magnitude of the associations between light at night and melatonin level suggests that multiple factors may be operating along the pathway between shift work and adverse health consequences (including cancer risk).
Here we propose four additional mechanisms that should be considered for a comprehensive investigation of these potential pathways.
These are:
- phase shift;
- sleep disruption;
- lifestyle factors (such as poor quality diets, less physical activity and higher BMI); and
- lower vitamin D.
Consideration of all these mechanisms is necessary in order to design effective preventative workplace strategies. In developed countries, approximately 20% of the population undertake shiftwork and, while we are unlikely to be able to eliminate shiftwork from current work practices, there are aspects of shiftwork that can be modified and there may be facets of individual susceptibility that we may be able to identify and target for prevention.
PMID: 21723672
Adverse Metabolic Consequences in Humans of Prolonged Sleep Restriction Combined with Circadian Disruption
Sci Transl Med 11 April 2012: ; Vol. 4, Issue 129, p. 129ra43
Sci. Transl. Med. DOI: 10.1126/scitranslmed.3003200
Orfeu M. Buxton1,2,*, Sean W. Cain1,2, Shawn P. O’Connor1, James H. Porter1, Jeanne F. Duffy1,2, Wei Wang1,2, Charles A. Czeisler1,2 and Steven A. Shea1,2
1 Division of Sleep Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA.
2 Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, USA.
*To whom correspondence should be addressed. E-mail: orfeu_buxton at hms.harvard.edu
Epidemiological studies link short sleep duration and circadian disruption with higher risk of metabolic syndrome and diabetes. We tested the hypotheses that prolonged sleep restriction with concurrent circadian disruption, as can occur in people performing shift work, impairs glucose regulation and metabolism. Healthy adults spent >5 weeks under controlled laboratory conditions in which they experienced an initial baseline segment of optimal sleep, 3 weeks of sleep restriction (5.6 hours of sleep per 24 hours) combined with circadian disruption (recurring 28-hour “days”), followed by 9 days of recovery sleep with circadian re-entrainment. Exposure to prolonged sleep restriction with concurrent circadian disruption, with measurements taken at the same circadian phase, decreased the participants’ resting metabolic rate and increased plasma glucose concentrations after a meal, an effect resulting from inadequate pancreatic insulin secretion. These parameters normalized during the 9 days of recovery sleep and stable circadian re-entrainment. Thus, in humans, prolonged sleep restriction with concurrent circadian disruption alters metabolism and could increase the risk of obesity and diabetes.
Copyright © 2012, American Association for the Advancement of Science
Article in Kurzweilai.net which read the above study and reported on it
Background
A growing body of epidemiological data that indicates shift workers are at an increased risk of
- weight gain,
- metabolic abnormalities,
- heart disease,
- diabetes, and
- obesity, among other disorders.
In 2007, the World Health Organization (WHO) even classified shift work as a probable carcinogen, due to accumulating evidence that disruptions to the circadian rhythm increased the risk of developing certain cancers.
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It is interesting that every one of these diseases also are associated with having a low level of the sunshine vitamin
The following found NO association of low vitamin D in a few shift workers where their shifts were constantly rotating thus having access to middle-of-the-day sunshine many times per month
Association between night-shift work and serum 25-hydroxyvitamin D levels in Japanese male indoor workers: a cross-sectional study
Ind Health. 2011;49(5):658-62. Epub 2011 Aug 1.
Itoh H, Weng Z, Saito H, Ogawa Y, Nakayama K, Hasegawa-Ohira M, Morimoto K, Maki S, Takahashi M.
National Institute of Occupational Safety and Health, Kawasaki, Japan. itoh-hiroaki at umin.ac.jp
Although low vitamin D status resulting from night work is a suspected cause of various health disorders, few studies have investigated the association between night-shift work and vitamin D status. Here, we examined serum 25-hydroxyvitamin D (25OHD) levels in 19 Japanese indoor workers, including night-shift workers, in blood samples collected at the annual medical checkup (late July) in a metal tool factory. Analyses were finally restricted to 14 male workers (33-59 yr) in 3 groups: fixed daytime work (n=6), and rotating shift work with (n=4) and without (n=4) night shifts. No significant differences in serum 25OHD levels were observed among the three groups (p=0.98, Kruskal-Wallis test). One to two participants in each group had 25OHD levels lower than the 20 ng/ml reference value for vitamin D deficiency even in summer. These results clearly indicate the need for large-scale studies to test the hypothesis that night-shift work is associated with lower 25OHD levels.
PMID: 21804263 CLICK HERE for full text on-line
Long-term shift workers 48% more likely to get Breast Cancer - Vit D and Melatonin suspected - Review Dec 2015
[Night work, shift work: Breast cancer risk factor?]. [Article in French]
Gynecol Obstet Fertil. 2015 Dec;43(12):791-9. doi: 10.1016/j.gyobfe.2015.10.004. Epub 2015 Dec 1.
Benabu JC1, Stoll F2, Gonzalez M3, Mathelin C4.
OBJECTIVE: The aim of this review was to determine the link between night/shift work and breast cancer.
METHODS: The analysed articles were taken from the PUBMED database between 1996 and 2015. The keywords used were "breast cancer risk", "night work" and "shift work". In total, 25 articles were selected.
RESULTS: Night/shift workers are more at risk to develop a breast cancer (relative risk (RR) between 1.09; 95 % CI: 1.02-1.20 and 1.48; 95 % CI: 1.36-1.61 in the meta-analyses). However, this risk is not found by some cohort and case-control studies. The circadian rhythm disruption, responsible of disorderliness of melatonin secretion, could be one of the mechanisms involved in the increase of that risk. Hormonal status of night/shift workers, their geographic origin, their lifestyle and their vitamin D deficiency appear as other mechanisms potentially responsible for increased risk of cancer in this professional population. Moreover, a dose-effect connection may exist, with an increase of the risk with the number of years of night/shift work.
CONCLUSION: Night/shift work is associated with a moderate increased risk of breast cancer, especially among women who worked over 20 years. Recommendations concerning the breast monitoring in this population could be diffused. The benefit of melatonin supplementation remains to be assessed.
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