Shift work

Shift work results in:

Fatigue, sleep disturbance, digestive problems, lack of concentration, memory loss and mood swings.

Shifts can follow a number of patterns:

Rotating of fixed

A rotating pattern involves working different hours each week or month.  A typical three shift system covering a 24 hour period would involve people working

• 6am to 2 pm
• 2pm to 10pm
• 10pm to 6am

Clockwise or anticlokwise

In addition the rotation can be clockwise or anticlockwise.  In the example above, week 1 would be 6am to 2pm in the first week and moving to the pm to 10pm in week to…and so on.  This is clockwise.  A backward (or anticlockwise) rotation would involve starting at am to 2pm in week one and then moving to the 10pm to 6am in week two…and so on.

With a rotating shift pattern there can be permanent desynchronisation between internal and external factors with the person never fully adjusting to the new shift. 

Exam advice:

The specification states that you need to know about disruption of biological rhythms… clearly suggesting more than one.  The two obvious ones suggested above are the effects shift work and of jet lag.  However, SAD is a disrupted biorhythm that can be seen as either circadian or infradian so can also be discussed in a question on disruption of rhythms. 

However, a much richer vein of material would be a discussion of the effects of sleep deprivation studies, covered in the sleep section.  Work by Dement, Jouvet, Rechtschaffen, Huber-Weidman  and the case studies of Randy Gardner and Peter Tripp look at the effects of disrupting the stages of sleep (ultradian) and the sleep-wake cycle (circadian). 

Fast or slow rotation

Although most research suggests a clockwise rotation is to be preferred, there is disagreement over the speed of rotation.  Czeisler (main man in this area) recommends a slow rotation, for example spending at least three weeks on each shift.  Bambra (2008) however, prefers a faster rotation of just 3 to 4 days on each pattern so the body never has time…