Broad Categories of Shift Work

Before looking at the problems that shift work poses in terms of sleep, we need to look in a little more detail at the two major categories of shift work – permanent and rotating – as there are significant differences between the two when it comes to examining sleeping problems.

Permanent Shift Work Schedules

As we've already said, a permanent shift work schedule involves working a fixed pattern of hours each day, outside of the normal working hours (7 a.m. to 6 p.m.).

Many people believe that working this particular shift pattern presents little or no difficulty once you get used to it. After all, the longer you do something the better you get at it and the easier it becomes. In addition, working a fixed pattern allows you to devise your own methods for coping with the problems that arise and let's you adapt to your working environment.

Unfortunately, however, research shows that permanent night shift workers do not adapt to this environment and that there are many nights when fatigue sets in and they complain of feeling tired and sleepy.

There are many reasons for this but the main one lies in the fact that the vast majority of night workers revert to their normal day/night schedule on their days off. The pressure of family and friends and the need to get on with the normal business of living, such as taking the car in for a service or repairing the garden shed, interrupts the process of adapting to their night working routine and sets them right back to square one.

In addition, many night shift workers do not follow a sound sleep routine while working shifts and invariably sleep less than they should, thus not allowing their body to recover sufficiently each day and building up their fatigue from day to day.

Rotating Shift Work Schedules

Working a rotating shift schedule presents you with the same problem of adaptation, but here the problem is compounded by the fact that your body simply doesn't have time to adapt before your schedule changes again.

The body can of course adapt to change, although it is slow to do so. If you fly half way around the world on holiday and find yourself in a time zone twelve hours adrift from your home town, your body will be thrown completely out of balance as day is suddenly turned into night and vice versa. But stay at your destination for any length of time and take the right measures to help your body to adjust and it will do so, normally within about a week. Now, fly home again at the end of your one week holiday and you need to start the process of re-adjusting your body all over again.

Working a rotating shift schedule presents exactly the same problem. However, this problem can be further complicated by two common features of a rotating shift schedule – the speed or rotation and its direction.

The Speed of Rotation

The speed of rotation simply refers to the number of consecutive shifts worked before a shift change takes place.

A slow rotation (for example working the same shift for perhaps two or three weeks before a change takes place) does give reasonable time for your body to adapt. However, you will need to go through this process of adaptation every two to three weeks.

In addition, many shift workers following this pattern will find that they have several days off between shift changes and here the same problems that we have already looked at for permanent shift workers arise.

In the case of a fast rotation (changing shifts perhaps every two or three days), your body simply doesn't have time to adjust at all. Some workers do however favor a fast rotation as it allows them to get through the unpopular shifts quickly and days off come around more frequently. This particular pattern of rotation is often seen in Europe although it is not looked upon so favorably in the United States.

The Direction of Rotation

The direction of rotation refers to the order in which your shifts change. If your shifts rotate in a clockwise direction (for example moving from an evening shift to a night shift, or from a night shift to an early morning shift) your rotation is said to be a “forward” rotation. Moving in an anti-clockwise direction (for example moving from an early morning shift to a night shift, or from a night shift to an evening shift) your rotation is said to be a “backwards” rotation.

As a rule, most shift workers find it easier to adapt to a forward rotation, rather than a backward one. This is because we generally find it easier to go to bed later and wake up later. A backward rotation forces us to sleep earlier and earlier and this works against our natural body rhythm.

Having looked at the categories of shift work let's move on to see why shift work causes sleep problems.