Shift work is a regular feature to our industrial society. We need people in the industry to work around the clock, in order to maintain the system that underpins our society. Peoples who job involves shift work face the problem of Zeitgebers, such as the onset of dawn and night time, remaining the same. As a result they are forced to adjust their natural sleep wake patterns to be the demand of shift work, in spite of the cues and triggers of Zeitgebers which suggest the opposite. This can holds huge implications, as research has shown that in a workplace, shift work can lead to a reduction in productivity and job satisfaction, and a higher accident rate (Pinel, 1997)
For most people it takes a week to before their circadian rhythms have adjusted to a new sleep wake cycle, yet many patterns of shift work do not take into account. Shift work can be organized in several ways. Research has indicated that the following shift patterns are most beneficial to both workers and employers.
- Rotation rather than remaining on the same shift.
- Changing shifts every three weeks or so rather than every week
- Changing in a clockwise rather than anticlockwise direction.
Monk and Folkard (1985) examined different pattern of shift work and found that changing shifts was more beneficial than remaining on one shift for a long time. Workers who rotated shifts were found to be more productive and create fewer errors which resulted in a fewer number of accidents. This is some what surprising as we would expect that it would be more beneficial to stay on the same shift. Monk and Folkard argue that shift rotation prevents an accumulation of sleep deprivation.
A study in Utah in the USA indicates that workers took about 16 days to adjust to a change in shifts (Cziesler et al 1982).The research recommend a change from the existing seven day shift rotation to a twenty one day rotation. They also suggest that workers move forward in time rather than backwards when changing shifts. This results in a phase delay rather than a phase advance.
With jet lag, like shift work, the 25 hour human clock appears to adjust more easily to phase delay rather than phase advance. The cause of conflict is between the travelers own circadian clock and external rhythms in a new time zone, such as day night time, meal times and rest activity cycles. Jet lag is a temporary disorder that causes fatigue, insomnia, and other symptoms as a result of air travel across time zones. Many factors influence the degree to which a traveler feels jet lag; age, direction of travel, number of time zones crossed, and individual differences in coping. .
Siffre’s 1975 experiences indicate that the natural (free running) circadian rhythm of the biological clock is around 25 hours. Traveling east shortens what is for the body an already shortened day. Traveling west, lengthened the day, which is what the body prefers
To reduce the effects of jet lag, methods have been used to manipulate the biological clock with a technique called light therapy. They expose people to different types of lights, many times brighter than ordinary household light, for several hours near the time the subjects want to wake up. This helps them reset their biological clocks and adjust to a new time zone.
Some have also suggested the use of melatonin to treat jet lag and to resynchronize the biological clock however there are potential dangers into the use of melatonin, as it does have a number of ill side effects.
For people who are subjected to total blindness, they are subjected to life long sleeping problems because their retinas are unable to detect light. These people have a kind of permanent jet lag and periodic insomnia because their circadian rhythms follow their innate cycle rather than a 24-hour one.
