Health consequences of shift work and insufficient sleep
BMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i5210 (Published 01 November 2016) Cite this as: BMJ 2016;355:i5210
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As a medical student nearing the end of my training, I, like many of my peers, have a degree of apprehension about how I will cope with shift work during foundations years. It was interesting to read of the long-term health effects of shift work, particularly the link with developing type 2 diabetes.1 Given many people in my situation face 30-40 years in the medical career, the potential for developing a chronic condition thus seems high.
However, some individuals enter their medical career with a pre-existing condition. I was diagnosed with type 1 diabetes nine years ago. The interactions I had with the healthcare profession had a significant impact on my choice of career. However, this review has instigated a question of the impact of shift patterns on those who already have conditions such as diabetes. From my experiences of clinical placements, the fast-paced environment lends little time to care for one’s self. For most people, this results in struggling to find time to eat or drink. For me, this is simply not an option. Maintaining good glycaemic control truly requires a lot of effort. Barely ten minutes go by without me wondering “What are my blood sugars? Do I need to eat anything?” When I finally qualify, this will become even more important as the consequences of hypoglycaemia could be catastrophic on patient safety. Fortunately, insulin pump therapy has thus far relieved some of these stresses. The potential advent of closed-loop systems make me positive that there will be further reductions in the brainpower needed to maintain good glycaemic control.2
Some studies have successfully shown links between shift work and poor outcomes in type 1 diabetes. Young et. al. showed a significant rise in HbA1c among diabetics at a Canadian hospital who worked shift patterns.3 However, research in this area appears limited, and fails to explore the difficulties that insulin controlled diabetics face during shift work.
While this issue affects a relatively modest proportion of the workforce, it is an important one for those concerned. I remain anxious to see how I will adapt to the life of a doctor. I have little doubt that my diabetes will suffer, at least initially. Better evidence of the effects of shift work are needed to provide advice to patients how best to manage blood glucose during this situation. The necessity is even greater in high stakes public service jobs like those of the doctor.
1. Gan Y, Yang C, Tong X, et al. Shift work and diabetes mellitus: a meta-analysis of observational studies. Occupational and Environmental Medicine 2015;72(1):72-78.
2. Battelino T, Omladic JS, Phillip M. Closed loop insulin delivery in diabetes. Best Pract Res Clin Endocrinol Metab 2015;29(3):315-25. doi: 10.1016/j.beem.2015.03.001 [published Online First: 2015/06/09]
3. Young J, Waclawski E, Young JA, et al. Control of type 1 diabetes mellitus and shift work. Occupational Medicine 2012
Competing interests: No competing interests
As obstetricians and gynaecologists, we read about the adverse health consequences of shift work and insufficient sleep (doi: http://dx.doi.org/10.1136/bmj.i5210) with both personal and professional interest. Although the authors state, “some people are more resilient to shift work than others”, they do not mention women: who make up a large proportion of shift and night workers, and undoubtedly the majority in the NHS.
Women account for almost half the working population, contribute significantly to the world economy and the majority of workers are of reproductive age. Circadian control is found throughout the hypothalamic-pituitary axis in women, playing a role in the timing of ovulation and progesterone secretion. Inappropriate exposure to light in order to deliberately deregulate circadian rhythm has been shown to negatively impact upon mammalian implantation and pregnancy success (1, 2). Human reproductive outcomes are reliant on circadian timings and previous systematic reviews have revealed associations between shift work and increased risks of preterm birth, low birth weight, fetal loss as well as menstruation, fecundity and early pregnancy complications (3-6). The workforce, and the NHS in particular, depends on women. Whilst the associations may be affected, or even explained, by confounders (i.e. class, income, smoking etc.), women’s specific reproductive concerns and amelioration should have been considered.
1. Sellix MT, Menaker M. Circadian clocks in mammalian reproductive physiology: effects of the "other" biological clock on fertility. Discov Med. 2011;11(59):273-81.
2. Summa KC, Vitaterna MH, Turek FW. Environmental perturbation of the circadian clock disrupts pregnancy in the mouse. PLoS One. 2012;7(5):e37668.
3. Physical and shift work in pregnancy : occupational aspects of management: a national guideline. London: Royal College of Physicians of London; 2009.
4. Knutsson A. Health disorders of shift workers. Occup Med (Lond). 2003;53(2):103-8.
5. Palmer KT, Bonzini M, Bonde JP, Multidisciplinary Guideline Development G, Health, Work Development U, et al. Pregnancy: occupational aspects of management: concise guidance. Clin Med (Lond). 2013;13(1):75-9.
6. Stocker LJ, Macklon NS, Cheong YC, Bewley SJ. Influence of shift work on early reproductive outcomes: a systematic review and meta-analysis. Obstet Gynecol. 2014;124(1):99-110.
Competing interests: No competing interests
Interesting facts highlighted in your article. It is known that stress causes so many diseases, especially cardiovascular diseases, and we as medical staff should be aware of its iceberg effects. Quantifying risk with the diseases highlights its importance, as pointed out by your article.
Competing interests: No competing interests
As a House Officer at Charing Cross Hospital during the Summer of 1990, I recall finally trying to sleep at 12am following no rest at all for the previous 16 hours. After what was broken sleep through intermittent bleep activity, I experienced what I can only describe as auditory and visual hallucinations in the context of dehydration, fatigue and sleep deprivation. Such experiences can never be forgotten. I am probably not alone. Others of a similar generation will, no doubt, have equally unpleasant experiences that we cannot allow to be repeated.
Competing interests: No competing interests
Firstly, thank you for a fascinating piece of research. It is a truly monumental undertaking and deserving of the profession's approbation. It also needs to be considered in light of the hours worked by junior doctors and nursing staff who are working shifts that do not allow the body to acclimatize to rapidly changing hours and work loads.
In 1986/7 I caught the measles just prior to finals and was consequently a student for an extra 6 months. The change in my colleagues as they transitioned from Student to Junior Doctor was quite depressing and so I undertook a small project looking at the effects of stress and fatigue on Junior Doctors. A number of psychometric tests were run on the morning and afternoon of two consecutive days when junior doctors had worked on-take the night in between. Choice Reaction Time increased with increasing numbers of mistakes, Critical Flicker Fusion time decreased. Of most significance however was the deterioration in the Intelligence Quotient from an average of 120 on the morning of the first day to "below 80" on the afternoon of the second day. (The test was only accurate above an IQ score of 80.) Memory also deteriorated significantly between the morning of the first day and the afternoon of the second. To give all this some meaning, we repeated all the tests when the subjects were fully rested on a Sunday morning but had been given sufficient alcohol to raise their breath levels to above 40, the then legal limit for driving). I was able to conclude that Junior Doctors would be safer drunk than tired.
Unfortunately, when I asked my consultant if it were worth publishing I was asked, do you really want a career in medicine? The implication was that publishing such a study would mark me as a trouble maker and I bottled out. Some years later when through sheer fatigue I made a mistake that killed a patient, I wish I had acted very differently.
That is why I hope very sincerely, that senior colleagues will read this much more professional study and consider its implications for those whose role in life is to care for patients.
Competing interests: No competing interests
Re: Health consequences of shift work and insufficient sleep
Letter to Editor, British Medical Journal.
Salivary cortisol testing should be used as a screening tool for HPA-axis disruption in shift workers
The recent review article on the health consequences of shift work and insufficient sleep was both interesting and thought-provoking.[1] This issue may become even more important now that we will soon be leaving the European Union and therefore no longer be subject to European working time regulations.
Work-related stress has considerable impact on employees’ well being and several studies have suggested that stress, particularly during shift work, and sleep deprivation contribute to chronic illness such as diabetes, depression and breast cancer. [1-3] One potential mechanism is overactivity of the Hypothalamo-Pituitary-Adrenal (HPA) axis, which initially causes stress and later results in depression. Meerlo et al have shown that after 48 hours of total sleep deprivation, adrenocorticotrophic hormone (ACTH) and cortisone levels are increased, and following a 4-hour recovery period, the subsequent response to stress is weakened. These results indicate that sleep deprivation not only is a mild activator of the HPA axis itself, but also affects the subsequent response to stress.[4] Cosgrove et al have shown that there is an increased risk of type 2 diabetes in patients with depression.[5]
Salivary cortisol testing is easy, safe, non-invasive, affordable and accurate, and could be used as a screening tool in shift workers to allow early detection of HPA-axis disruption.[6] This technology needs some standardisation because of some existing variability between diagnostic devices and laboratory techniques, [7] . Increased cortisol levels would be expected in cigarette smokers because nicotine is a stimulant of the the HPA-axis.[8] Nevertheless, salivary cortisol measurements would prove to be a cost effective screening tool in shift workers and should be part of HSE recommendations.
Dr. Anna Alexander MRCGP
Dr Pothen Alexander MRCGP
General Practitioners, Ifield Medical Practice, Crawley, West Sussex.
References
1. Kecklund G, Axelsson J. Health consequences of shift work and insufficient sleep. BMJ (Clinical research ed.) 2016;355:i5210 doi: 10.1136/bmj.i5210[published Online First: Epub Date]|.
2. Pitchot W, Herrera C, Ansseau M. HPA axis dysfunction in major depression: relationship to 5-HT(1A) receptor activity. Neuropsychobiology 2001;44(2):74-7 doi: 54919[published Online First: Epub Date]|.
3. Wang XS, Armstrong ME, Cairns BJ, et al. Shift work and chronic disease: the epidemiological evidence. Occupational medicine (Oxford, England) 2011;61(2):78-89 doi: 10.1093/occmed/kqr001[published Online First: Epub Date]|.
4. Meerlo P, Koehl M, van der Borght K, et al. Sleep restriction alters the hypothalamic-pituitary-adrenal response to stress. Journal of neuroendocrinology 2002;14(5):397-402
5. Cosgrove MP, Sargeant LA, Griffin SJ. Does depression increase the risk of developing type 2 diabetes? Occupational medicine (Oxford, England) 2008;58(1):7-14 doi: 10.1093/occmed/kqm105[published Online First: Epub Date]|.
6. Lac G, Chamoux A. Elevated salivary cortisol levels as a result of sleep deprivation in a shift worker. Occupational medicine (Oxford, England) 2003;53(2):143-5
7. Wartofsky L, Handelsman DJ. Standardization of hormonal assays for the 21st century. The Journal of clinical endocrinology and metabolism 2010;95(12):5141-3 doi: 10.1210/jc.2010-2369[published Online First: Epub Date]|.
8. Kudielka BM, Hellhammer DH, Wust S. Why do we respond so differently? Reviewing determinants of human salivary cortisol responses to challenge. Psychoneuroendocrinology 2009;34(1):2-18 doi: 10.1016/j.psyneuen.2008.10.004[published Online First: Epub Date]|.
Competing interests: No competing interests