By Jia Ying Tan
We all know what happens when we don’t get enough sleep. The significance however of sleep and heart health are less spoken about and importantly have far-reaching consequences in the medical workforce. I never truly understood this until I started a job as a foundation doctor. The rigorous shift patterns of the rota required a complete adjustment in almost every aspect of my life, especially my sleep patterns.
Sleep has been found to be an important regulator of cardiovascular and metabolic functions in the body. (Santos et al., 2020) Sleep deficiency is defined as any disruption to normal sleep duration, timing and quality. (Kohansieh and Makaryus, 2015) It is the dysfunction of this crucial part of life that can result in impaired decision-making causing work-related catastrophes e.g., Chernobyl radioactive disaster of 1968. (Owens, 2018) In 2018, it was found that there were a whopping 3 million people who worked night shifts in Britain alone. (Trades Union Congress, 2018) Turning day into night is a part of the job for healthcare workers as well as other professions. It is well established that shift work is associated with poor sleep – something that I can definitely attest to. Equally important is the question of heart health i.e. while it is an issue of public health, it is equally important for us to take ownership of this. Heart health is influenced by modifiable and non-modifiable risk factors. Modifiable risk factors like obesity, diabetes, dyslipidemia and smoking are integrated into a QRISK score which is used in clinical practice to initiate statin prescribing. (QRISK3, no date) Sleep deficiency is increasingly linked to these cardiovascular risk factors potentially impacting on the secondary prevention of heart disease. It is clear that sleep and heart health are incredibly interlinked in more ways that we can understand.
So how does sleep affect our heart?
The pathophysiology of poor sleep on the heart is centred around blood vessel pathology. The endothelium and blood vessel patency are key to optimise the ability of the heart to pump blood to our peripheries. Studies show endothelial dysfunction occurs in people who are sleep deprived due to increased release of inflammatory mediators like nitric oxide. In particular, reduced vasodilation and increased vasoconstriction accelerates development of plaques, increasing likelihood of atherosclerotic changes to blood vessels. (Liu and Chen, 2019) This is the crux of evidence surrounding sleep and heart health. Essentially, the more sleep deprived we are the quicker aging processes of the heart occur.
Our internal ‘body clock’ is a complex system of synchronized feedback loops; attuned to light, temperature and food. This is the circadian rhythm and its main focus goes beyond making sure we all go to sleep. The effects of circadian disruption on heart health show derangement of markers of cardiovascular function e.g., blood pressure (BP) and heart rate (HR). BP and HR are also indicators that the autonomic nervous system (ANS) is working. (Santos et al., 2020) So not only does it affect our coronary vessels but globally, our bodily systems are negatively impacted when we don’t get enough sleep.
Obstructive sleep apnoea (OSA) is the most recognized sleep related disordered breathing associated with serious cardiovascular complications. In OSA, the ANS is implicated in development of cardiovascular disease specifically increased sympathetic activity and parasympathetic withdrawal. Research has shown that heart rate variability is an indicator of how the body adapts heart rhythm to autonomic changes. Consequently, acute sleep deprivation causes major physiological responses like increased blood pressure. (Santos et al., 2020)
How does this affect the medical workforce?
It is common for shift-workers to modify sleep schedules when necessary. This causes significant circadian misalignment potentially resulting in poor cardiovascular outcomes. (Amirian, 2014) Furthermore, it is established that the sleep disruption in OSA patients who are shift-workers are an independent cardiovascular risk factor attributed to increased sympathetic drive. (Santos et al., 2020) According to a study done on surgeons, it was found that working night shifts had greater loss of sleep duration by 2-4 hours on average. (Amirian, 2014) Along with the fear that errors in decision making can be dangerous to patients, healthcare workers should be mindful of the harmful effects to their own health. Healthcare professionals constantly changing sleep schedules due to rotating night shifts may occasionally experience sleep deprivation, the severe form of sleep deficiency. It is clear that long term consequences of severe and constant circadian disruption with particular focus on cardiovascular disease should be investigated further. Aside from highlighting this demographic, we must think whether this pattern of work has negative impacts on heart health to all of the shift working population. This could represent an occupational hazard that affects millions of the nations’ workforce.
A systematic review looking at psychiatric effects of the COVID-19 pandemic on health workers found that sleep disorders would be more significantly affected compared to other occupations. (da Silva and Neto, 2021) The increasing burden and pressures on healthcare systems across the world due to the COVID-19 pandemic means sleep deprivation may well be an issue affecting many healthcare workers. Long shift work combined with irregular work schedules and increased pressures on all healthcare centres can only exacerbate sleep disorders in healthcare workers. (da Silva and Neto, 2021) As the pandemic wears on, we may see a rise in cases of cardiovascular diseases especially in this demographic.
In conclusion, sleep and heart health are undoubtedly interlinked; it is clear that sleep plays an important role in regulating physiological processes but significantly in cardiovascular system. To be specific, poor sleep quality and short sleep duration are markers that have been linked to adverse cardiometabolic outcomes. (Pizinger, Aggarwal and St-Onge, 2018)
From this, it is evident that shift work patterns have a negative impact on heart health. If it is here to stay, systematic changes need to be implemented to support healthcare workers in altering sleep patterns and optimizing sleep hygiene of workers. Occupational health has an important role to play in making these important changes and should be increasingly involved with staff to gather feedback on how we can be better supported.
Author: Jia Ying TanReferences
Amirian, I. (2014) ‘The impact of sleep deprivation on surgeons’ performance during night shifts’, Danish Medical Journal.
Kohansieh, M. and Makaryus, A. N. (2015) ‘Sleep Deficiency and Deprivation Leading to Cardiovascular Disease’, International Journal of Hypertension. Hindawi Publishing Corporation. doi: 10.1155/2015/615681.
Liu, H. and Chen, A. (2019) ‘Roles of sleep deprivation in cardiovascular dysfunctions’, Life Sciences. Elsevier Inc., pp. 231–237. doi: 10.1016/j.lfs.2019.01.006.
Owens, R. (2018) The Science of Sleep, Collection Development, Library Journal. Available at: https://www.libraryjournal.com/?detailStory=ljx180901CollectionDevelopmentSleepDisorders (Accessed: 2 April 2021).
Pizinger, T. M., Aggarwal, B. and St-Onge, M. P. (2018) ‘Sleep extension in short sleepers: An evaluation of feasibility and effectiveness for weight management and cardiometabolic disease prevention’, Frontiers in Endocrinology. Frontiers Media S.A., p. 392. doi: 10.3389/fendo.2018.00392.
QRISK3 (no date). Available at: https://qrisk.org/ (Accessed: 2 April 2021).
Santos, I. et al. (2020) ‘Obstructive sleep apnea, shift work and cardiometabolic risk’, Sleep Medicine, 74, pp. 132–140. doi: 10.1016/j.sleep.2020.05.013.
da Silva, F. C. T. and Neto, M. L. R. (2021) ‘Psychiatric symptomatology associated with depression, anxiety, distress, and insomnia in health professionals working in patients affected by COVID-19: A systematic review with meta-analysis’, Progress in Neuro-Psychopharmacology and Biological Psychiatry. Elsevier Inc., 104, p. 110057. doi: 10.1016/j.pnpbp.2020.110057.
Trades Union Congress (2018) Number of people working night shifts up by more than 150,000 in 5 years. Available at: https://www.tuc.org.uk/news/number-people-working-night-shifts-more-150000-5-years (Accessed: 2 April 2021).
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