Caffeine, chronic disease & cancer-health effects of shift work.

Tweet about this on TwitterShare on FacebookShare on LinkedInShare on Google+

It’s quite a few years since I was a junior doctor, doing marathon hospital shifts. But I still remember the awful shivery tiredness at 4AM- running from ward to ward, grabbing cups of bad instant coffee every few hours to keep my brain fired up. And then there was the exhaustion the following day- driving home with the window rolled down to keep myself awake after 30 straight hours of work without sleep. It was always obvious to me that it was a very unhealthy lifestyle.

Shift work is any job that is undertaken outside normal daylight hours (it doesn’t have to be overnight to qualify as shiftwork- for example, a gym instructor who works early mornings and evenings would qualify as a shift worker). The effects on health probably rise in part from disturbances to “circadian rhythm” – which is basically the night and day chemistry of our bodies, closely related to exposure to light. But there are also the social effects of shift work- the pressure on relationships and family life, and the simple practicalities of what to eat when it’s 4AM and the only food to be had is calling to you seductively from a vending machine!

In 2007 the World Health Organisation classified shift work as a “possible carcinogen” or cancer causing health risk. Research suggests a link between shift work and breast cancer-and there is limited, though inconsistent evidence for links with other cancers, such as colon cancer. It also appears there may be a higher risk of heart disease, obesity, hypertension, and type 2 diabetes. Some studies indicate an increased risk of preterm delivery, gastrointestinal disorders and mental health problems among shiftworkers. However, the bottom line is that more research is needed in many of these areas to confirm the associations. Injuries and accidents also seem to occur more frequently amongst shift workers-  with an estimated increase of 15% on evening shifts and 28% on night shifts.

For many people, shift work is just a passing phase, for others it will be a long term way of life.  Whilst the science may not yet be definite, it does appear that shift workers are more prone to quite an array of health issues. What to do about it? Well, a responsible employer will schedule shifts to reduce the negative impact on workers- most countries have specific guidelines and laws on this. Steps to maximise physical fitness and healthy eating would seem sensible. Given the possible increased cancer risk among shift workers, smoking should certainly be avoided like the plague. And in terms of the impact on social and family life, shift workers may benefit from more proactively planning their time off, to nurture their friendships and relationships. Certain medications, such as Melatonin may also help with triggering sleep.

Anyone whose job involves long term shift work would be wise to have a good check up with their GP every year or two- with assessment of fasting blood sugar, blood pressure and weight measurement -and to discuss any concerns they may have regarding sleep, mental health or other health issues. Like so many things in life, when it comes to being a shift worker-being proactive is always better than being reactive!

by Dr Aifric Boylan

Comments are closed.

As seen on

Pay securely via Paypal.