This is the second publication in as many weeks about the latest research reinforcing the impact shift working has on women’s’ health. Last week it was about night shifts doubling the risks of breast cancer and now this week the University of Southampton has identified causal links between shift work and fertility problems.
Both pieces of research do conclude nothing is certain and more research will be needed before anything more conclusive can be declared. In this latest research the fertility outcomes of over 119,000 women working non-standard working hours i.e. shifts, were compared to women working what is described as regular hours e.g. 9-5d or ‘office hours’.
It concluded women working shifts had a 33% higher rate of menstrual disruption than those working regular hours and an 80% increased rate of subfertility.
However the research does ‘home in’ on one factor worthy of further study: the impact on circadian rhythms or our “body clock” referred to in this research as “clock genes”.
For sure, there are such things as ‘friendly’ and ‘unfriendly’ shift patterns. This research concludes the optimal shift pattern required to maximise reproductive potential is yet to be established. In fact, when we start considering the word “optimal”, or “optimization”, for any shift pattern we are in “very hard problem” territory.
We can however, take a look at what makes a shift pattern more ‘friendly’ in the context of this research. There are essentially two factors you need to consider when tuning shift work to your internal body clock:
- The Direction of Rotation (DOR). This is about the order you work different shifts; and
- The Speed of Rotation (SOR). This is about the speed you change, or swap, from one shift to another.
These are simple concepts however, except for the most trivial shift pattern, they are very difficult in practice to manually work out in spreadsheets.
As far as the DOR goal goes you need to order the different shifts so when you change, or swap, from one shift to another the shift start times are getting progressively later. For example, 7am-3pm followed by 3pm-11pm; and finally 11pm-7am before taking days off. This is known also as ‘forward’ of ‘clockwise’ rotating shift pattern. The opposite to this would be 11pm-7am followed by 3pm-11pm; and finally 7am-3pm followed by days off. In other words shift start times are getting progressively earlier; and is known as the ‘backward’ or ‘counter clockwise’ rotating shift pattern.
As far as the SOR goal goes a faster rotation is to be preferred than a slower rotation. For example, two days working 7am-3pm followed by two days working 3pm-11pm; and finally perhaps two days working nights. This is only an example to get this point across, much more is involved in designing friendly shift patterns that are practical in the real world. It can be contrasted with a week working 7am-3pm, followed by a week of 3pm-11pm and finally a week of nights – probably the worse combination you can think of for increasing the effects of sleep deprivation, fatigue and risk.
In this example we have used three types of shift. If you have five or more to deliver flexible working patterns then it is much harder to work out. To do this efficiently and effectively you will need to use something like the Schedule24 Excel Add-in. This has the chronobio controls that manages these two factors automatically; and generate any number of shift patterns that will tune out the worse effects shift working may have on your ‘body clock’. It also enables you to stay with what for many is their favourite spread sheet environment to make further modifications and formatting staff schedules.
So to summarise:
- Your employer needs to be aware; and know what can sensibly be done;
- Adopt a forward or clockwise (DOR) rotating shift pattern;
- Adopt a faster rather than a slower (SOR) rotating shift pattern;
- Avoid 12 hour shifts. These are technically ‘alternating’ not rotating shifts and chronobio benefits much harder to achieve;
- Publish and keep to the schedule in the long-term;
- Avoid breaking pattern routine with short notice changes and shift swapping; and finally
- Don’t blame it on the shift pattern when your WADES lifestyle compromises common sense.
To learn more about our automated shift pattern generator for Microsoft Excel, click here.