Is your night shift killing you?

Picture the scene. It's 2.00am and you're three coffees and two bags of m&ms down and you've lost count of how many laps of the ward you've done. You're on the first shift of a week of nights and sure, the hospital is quieter, somewhat more manageable, but this is killing you.

No really, this could be killing you.

According to researchers, our bodies are straight up not designed to be going at night and the disruption to our natural circadian rhythm may well result in cardio-metabolic disease.

A team at Charles Sturt University looked at a group of healthy males and split them into two groups; shift workers and non-shift workers.

They did pre-screening questionnaires to do with their general health and screened for existing disorders pre-trial, from diabetes to pre-existing arrhythmias or cardiovascular conditions.

"What we found is that shift workers, even apparently healthy shift workers, did have increased risk markers for future cardiometabolic conditions," said researcher and PhD candidate Blake Collins.

Collins tested people during work using things such as a glucose tolerance test.

"Basically you drink a specific amount of a sugary drink and then over a two hour time course we see how quickly the body metabolises or removes that glucose, and if you're taking longer to metabolise that glucose it's a risk factor for type 2 diabetes," he tells Aged Care Insite.

"We also looked at things like their cardiorespiratory fitness, current things like kidney levels, those kinds of generic markers of health as well, and that's what we found — shift workers had increased risk markers for future disease states."

Approximately 1.4 million people work shift work in Australia, making up 16 per cent of all employees.

Over two-thirds (68 per cent) of shift workers worked full-time and over half (55 per cent) were men..

Around 46 per cent of nurses worked a rotating shift in 2015.

Collins says that there could be a few different reasons why shift work doesn't agree with the human body.

First, access to healthy food can be difficult late at night and he says that shift workers are also more likely to smoke or engage in similar unhealthy behaviours.

But equally, the body's natural 24 hour rhythms struggle to adapt to night shifts.

"We see this in core temperature for example. There'll be times during the day that your core temperature is at the lowest, and times that it increases," Collins says.

"Your heart rate, blood pressure, those kinds of things are all on this rhythm and it's regulated by cues, and those cues for basically exposure to light, when you eat something and when you're physically active. So, those three factors train the body into that 24 hour rhythm and that's what helps control our normal function."

If you're doing a night shift, everything in your body is telling you that it's time to go to sleep but you're giving it mixed biological signals.

"You've got an artificial light on, you're being physically active, all these things that are basically sending these mixed biological signals to the body which we've seen can acutely affect cardiometabolic health," Collins says.

"And then our theory was that, well, if it acutely does that, people that are involved in shift work chronically will then start to exhibit those same chronic risk factors."

Another area of work Collins and his team are looking at is whether acute bouts of exercise could balance the negative effects of shift work.

"If you exercise before a shift, then we know that the shift is going to affect, say, your insulin sensitivity negatively, but exercise positively affects your insulin sensitivity.

"So, was it the case that we could acutely do some things to offset those negatives? And then if that becomes chronic, we could encourage all of our shift workers to exercise, then that would potentially offset the negative effects of doing shift work."

Exercise has been shown to increase attention and decrease fatigue, Collins says, so if you are a health worker doing a 12-hour night shift and fatigue is setting in, a short hit of cardio might be a useful intervention.

Collins' research looked at males largely because of the businesses he had access to in Bathurst, such as prisons and mines, but a future area of research would include female participants and a hospital setting would throw up a lot of interesting questions as to the best way to combat the negative effects of night shifts.

"So, does it matter if you do clockwise rotating shifts? So, should you go from a morning to an afternoon to a night. Go anti-clockwise?" Collins wonders.

"The length of the shift is another one. Is it more beneficial to do shorter shifts?

"Some people prefer, if you do a couple of 12 hour shifts, even though it's a longer disruption, you have to do less shifts. Whereas if you do eight hour night shifts, you'd have to do an extra night in that rotation to work the same hours.

"So, that's another area that's becoming quite topical that we're looking into."

Collins says that the way our society is set up, there is no way around shift work, so the focus should be on the interventions which keep our working population as healthy as possible.

Shift work has also been shown to have other adverse impacts on health. Nearly half of all men and women working shifts report suffering from chronic health complaints — such as back-pain, diabetes and chronic obstructive pulmonary disease — at a higher rate than the rest of the population.

And on top of the physical effects, night shift can impact on family life and overall wellbeing.

As Collins' work looked at only healthy males, more work must be done to look at how shift work affects other cohorts. But the fact that it affects otherwise healthy people is significant and could be a wake up call for other not-so-healthy shift workers.

"There's been some studies that have shown that you can start to adapt to it. But, basically, if you want to make it really simple, the human body isn't designed to be physically active and working at night and then sleeping during the day, and vice versa," he says.

"I think if you talk to most people, the advantages of shift work is generally monetarily-wise, increased days off, those kinds of things. Most people will agree that it's not having a fantastic effect on your health."

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