Shift-workers have higher rates of health problems

For those of us who have worked shift work, we know it can be hard to deal with and take a real toll particularly if we are not sleeping well or our health is not good.  Some of the effects of shift work are more obvious such as feeling sleep deprived or sleepy but others are more subtle and occur over time.  These can be adverse health effects like increased risk of diabetes, hypertension, obesity and even cancer.

How does shift work cause problems?

There are a number of different shift rotations and each of them can cause difficulties with sleep.

Long shifts, such as multiple 12- or 14-hour shifts in a row result in sleep deprivation as there is not enough time for sleep, particularly when factoring in time to wind down after work and commute to and from work.  Research from Europe shows that once people have worked more than three 12-hour shifts in a row they begin to feel sleepy as a consequence of sleep deprivation.

Another form of shift work is rotating shifts.  Whilst most people can deal with a gradual rotation of later shifts such as working day shift for a few weeks then afternoon shift for a few weeks, if shifts are changed rapidly such as multiple day or afternoon shifts within one week, it can lead to problems with not getting enough sleep and can also upset the circadian rhythm.  This is particularly the case if there are night shifts interspersed with day shifts or rapid rotation between day and night shift.  When there is a mix of day and night shifts within the same week, it can be very hard to get to sleep and the symptoms are from both sleep deprivation as well as a jet-lag-like effect of trying to sleep during times when the body clock feels more alert.  This can have other health impacts as people end up eating meals or doing other activities at a time when they would expect to be sleeping, which makes the body handle energy and process its internal functions differently.

What is the long-term health impact of shift work?

Shift work has a number of long-term health impacts over and above feeling sleepy and just generally not well, which can occur during shifts.  In people who work long-term shift work there are increased risks of:

Obesity: It is not clear what the mechanism for obesity is but it most likely relates to a combination of circadian and metabolic factors, with meals being taken at a time when the body is not set up necessarily to process energy.  Also, with shift work it can be hard to prepare healthy meals or ensure that healthy meals are available.  Often on shifts the only food options available are not necessarily healthy options and if people are feeling tired to start with it can be hard to do the planning for healthy meal preparation.

Type 2 diabetes: In addition to causing obesity, long-term shift work can increase the risk of type 2 diabetes. When adjusted for the effect of diabetes, nurses working long-term night shift were are 24% increased risk of developing diabetes.

High blood pressure: In a study of workers in a German automobile plant, long-term shift work was associated with a 15% increased risk of high blood pressure.

Cancer: Research on nurses working long-term shift work has shown that nurses working night shifts for over 30 years were at a 36% increased risk of breast cancer.  Similar results have been seen in other studies of different working groups and for different cancers such as colon cancer. Based on this data, long-term shift work has been classed as a carcinogen (a recognised cause of cancer).

Anxiety and depression: In nurses from Norway, those that worked shifts with a quick turnaround, such as an afternoon shift followed by a morning shift were 8-10% more likely to have anxiety or depression than nurses not having a quick turnaround between shifts.

Accidents: People working rotating day shifts were twice as likely to have work-related accidents compared to those on regular shifts.

Why can some people deal with shift work and others can’t?

Our ability to tolerate both the sleep deprivation and rotating shifts of shift work vary between individuals.

Genetics: There has been research on a number of genes involved in the circadian rhythm such as the Period 3 (PER3) gene.  Those who have 2 copies of the PER35 gene, so are PER35/5,are less able to tolerate both sleep deprivation and rotating shifts and are more susceptible to the acute effects of shift work.  In other studies, variations of the BHLHE41 gene have shown that there are particular genic variants that mean that people are able to cope better with sleep deprivation.  As such, we will all know people who work shifts but seem to deal with it well, whereas others have trouble with shifts and a lot of this is due to our genetic makeup.

Age: As we get older, it is also harder for us to deal with both the sleep deprivation and rotations involved in shift work.  This is both because the sleep system becomes less robust over time and also because as we get older we develop other medical conditions that require a regular routine for optimal management.

Other health problems: People with other physical or mental health problems are less able to tolerate the demands of shift work. So, it’s not only getting older, but the other health problems that develop over time that make shift work harder to deal with over time.

What should I do if I am working shifts and worried about the impact?

Prevention is actually the best way to manage the impact of shift work and given that our susceptibility to the impact of shift work is often determined by genetics and other health factors the most important factor is to be conscious of our ability to tolerate sleep deprivation and rotating sleep times or even jet lag prior to committing to shift work. If we find that we have difficulty with either sleep or adjusting to different sleep timings, we probably should not commit to jobs that require shift work in the first place.

I see many people in their 40s and 50s stuck in shift work jobs that are having a significant impact on their health.  Whilst they would be better off not working shifts they feel it is often too late in their careers to consider retraining, whereas if they had looked at their ability to tolerate shift work in their 20s they may have been able to opt for other career options.

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