Cardiovascular Disease and Shift Work:

Is There A Connection And If So, What Can You Do About It?

It’s certainly no secret that shift work is taxiing on our health in more ways than one.  In fact I’m sure you can appreciate first hand just how challenging it is to work irregular hours day after day after day … or should I say night?

But what about cardiovascular disease?

Does working shift work enhance our risks of developing cardiovascular conditions such as hypertension and coronary heart disease?

The simple answer is ‘yes’.

And whilst the mechanisms for doing so vary, the fundamental driver behind this, is unhealthy sleep patterns – which I’m sure every single shift worker on the planet can relate too.

But exactly how does lack of sleep raise our risks of developing cardiovascular disease?

Well it essentially comes down to an overactive sympathetic nervous system, otherwise known as the fight-or-flight’ stress response arm of the nervous system which instigates a lot of physiological responses within the body including the release of stress chemicals that raise blood pressure and heart rate.  One of which includes cortisol.

Whilst this ‘fight -or-flight’ stress response can be a good thing (particularly when we’re faced with danger and need to escape from harm), ongoing sleep deprivation can actually cause this system to remain stuck in the ‘on’ position for long durations of time, which places a strain on blood vessels, especially those that feed the heart called the coronary arteries.

This was illustrated in a study which showed even modest reductions in sleep involving just one or two hours – led to an increase in a person’s heart rate, and significantly increased the systolic blood pressure within the blood vessels.

So essentially lack of sleep can impact on our heart health in a number of ways:

  • extended periods of sleep deprivation or wakefulness has been shown to raise both systolic and diastolic blood pressure due to an increase in sympathetic nervous system activity, otherwise known as the ‘fight or flight’ arm of then nervous system.
  • this overactive sympathetic nervous system raises levels of the stress hormone cortisol, which constricts blood vessels raising blood pressure.
  • release of human growth hormone or HGH, which plays an integral role in replenishing the lining of our blood vessels called the endothelium, is reduced during sleep deprivation.
  • sleep loss causes inflammation within the body, which is a key mechanism in the development of cardiovascular disease.  Certain inflammatory biomarkers used to measure this inflammation include TNF-α or tumor necrosis factor alpha, Interleukin 1, 6 and 17, along with CRP or C-reactive protein.

Now I don’t want everyone who reads this – to send them into a panic!

Because it’s certainly not all doom and gloom.  It comes down to understanding the risk factors associated with working 24/7, so that you can then make better choices and choose actions that are in the best interest of your health.

I also want to point out that association does not always mean causation.

Meaning cardiovascular disease, just like many diseases, are often multi-factorial in that there are usually other contributing factors (in addition to the lack of sleep) such as poor diet, sedentary behaviour, history of smoking etc. that can lead to cardiovascular disease.

However understanding the connection between lack of sleep and cardiovascular disease is extremely important (particularly for shift workers), because it helps us to appreciate how critically important sleep is, and why we should do what ever we can to protect both our sleep quality (and quantity) whilst working 24/7.

So what can you do to reduce your risk factors for developing cardiovascular disease whilst working 24/7?

  • First and foremost – prioritise your sleep.  The only two things that matter when you work 24/7 are prioritising your sleep, and taking action to improve your sleep.
  • Take action to minimise your ‘sleep debt’ in the first place.  This means becoming a “shift swapping ninja” of sorts, because at the end of the day, all rosters are not created equal and whilst they might fit into the parameters of your workplace’s rostering software and be referred to as “legal”, it doesn’t mean they’re necessarily sleep or fatigue friendly!
  • Given sleep loss leads to inflammation, reducing intake of high inflammatory foods such as refined carbohydrates which include white bread, cakes and pastries, fried foods, soft drinks and other sugar-sweetened beverages, along with high amounts of red meat is absolutely essential.  Instead replace with anti-inflammatory foods such as green leafy vegetables, nuts and seeds, olive oil, fatty fish (wild-caught salmon and mackerel), tomatoes, broccoli, avocados, turmeric and fruits such as blueberries, cherries and oranges.
  • For many clients who undertake my Better Sleep Intensive Program, one of my recommendations is to undergo pathological testing including a lipid profile which includes total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides.  This is because if you have a high level of LDL-cholesterol (often called bad cholesterol) and triglycerides, then you have an increased risk of heart disease.  In addition to cholesterol but certainly not limited to, I may also recommend inflammatory biomarker testing which includes C-reactive protein (CRP) or CRP, along with pro-inflammatory cytokines such as IL-1, IL-6, IL-17A, TNF-α to ensure there is no sign of systemic inflammation which can contribute to cardiovascular disease.

So given ongoing sleep loss causes our ‘fight or flight’ nervous system to become overactive, along with the promotion of low-grade inflammation, taking care of your heart health has never been more important for anyone working 24/7.

Audra x

 

References:

Grandner, M, Sands-Lincoln, M, Pak, V & Garland, S 2013, ‘Sleep duration, cardiovascular disease, an pro-inflammatory biomarkers’, Nature and Science of Sleep, vol. 5, pp. 93-107.

Kim, S, Jang, E, Kwon, S, Han, W, Kang, M, Nam, Y & Lee, Y 2016, ‘Night shift work and inflammatory markers in male workers aged 20-39 in a display manufacturing company’, Annals of Occupational and Environmental Medicine, vol. 28, no. 48, pp. 1-9.

Meier-Ewert, H, Ridker, P, Rifai, N, Regan, M, Price, N, Dinges, D & Mullington, J 2004, ‘Effect of sleep loss on C-reactive protein, an inflammatory marker of cardiovascular risk’, Journal of the American College of Cardiology, vol. 43, no. 4, pp. 678-683.

Tochikubo, O, Ikeda, A, Miyajima, E & Ishii, M 1996, ‘Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder’, Hypertension, vol. 27, no. 6, pp. 1318-1324.

Please note: I reserve the right to delete comments that are offensive or off-topic.

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