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The circadian control is a “clock” that synchronises the body processes and activities. This clock is located in suprachiasmatic nucleus (SCN) (or nuclei) in mammals. There is a pair of distinct groups of cells which is located in the hypothalamus. The destruction of the suprachiasmatic nucleus can result in the absence of regular sleep-awake rhythm causing a person to be sleeping at some very odd hours. In the nightshift workers this can cause the worker to suffer since the sequence in which his body triggers sleep is random and not in a particular sequence or rhythm. This can be dangerous especially when the nurses fall asleep during some very intricate operations and this can even cause the loss of lives of the patient. The SCN is the one responsible for the reception of information about the illumination through the eyes. The retina of the eye has photoreceptors and ganglion cells. The photoreceptors are responsible for vision and the ganglion cells are responsible for response to light. These cells have signals which follow a pathway commonly known as retinohypothalamic tract which leads to the SCN. When the cells from the SCN are removed and cultured an own rhythm is maintained in the absence of the external cues. Information on the lengths of day and night is taken to the retina by the SCN and the retina interprets it and takes it to the pineal gland which is a tiny structure with the shape of a pine cone which is located in the hypothalamus. The pineal secretes the hormone melatonin which is the response it gives back. Melatonin secretion during the day is low and is high during the night providing information about the day-night lengths.


The change in the work shifts before the circadian rhythm has had time to adjust to one sleep/wake cycle then the circadian rhythm becomes in a state of internal desynchronisation since it has had no enough time to adjust. This is because it is never in complete synchronisation to one another. There are various effects that come about with the changes in the work shifts and they can cause devastating effects if not controlled. Shiftwork has been blamed by many experts for the human error connected with nuclear power plant incidents, air crashes, and also most of the hospital incidences that are caused by negligence and human error. When a worker goes on a long period of nightshifts there is an accumulation of sleep which results in what is commonly referred to as ‘sleep debt’. This results in the nigh shift workers by the 5th night they are about 8 to 10 hours in sleep debt. This debt in sleep causes lapses in concentration and alertness with slow reaction times. This results in poor decision making leading to errors and accidents. Another effect caused are the ‘microsleeps’ in which the brain momentarily halts and does not react as expected to what one sees or hears around him/her. An example is where during the night one drives and realises that he/she has driven a considerable length of route which he/she was not aware of. There can also be negative moods caused by the lack of sleep which can cause conflicts both at work and at home. The change in the work shifts can result in:

  • Disorienting the circadian rhythm which is a 24 hour body cycle
  • Loss of sleep
  • Disorders of the gastrointestinal and cardiovascular systems
  • Affect a person’s family and social life
  • Chronic fatigue

The loss of sleep occurs since the day sleep is not as deep as the night sleep and also it is less refreshing as sleep at night. This occurs since the circadian rhythm are no longer synchronised due to the changes in the time the work is working.

Gastrointestinal disorders and also the digestive problems which include indigestion, heartburn, stomach-ache and the loss of appetite are mostly common among the rotating shift workers and less common among the day workers. The night workers also suffer from poor diet since most of the time they consume a lot of junk food due to the unavailability of well balanced meals at night. The cardiovascular diseases are not fully associated with night shifts but the heart rate and blood pressure have been shown to follow a circadian rhythm which if affected can result in the diseases worsening. A study conducted on Sweden men who had a history of heart attacks showed that they more likely to have been shift workers and the men who had not done shift works were less likely to have heart attacks.

Most of the shift workers and specifically those working at night report more interference with their family lives. This is because they have less time to spend with their families since at night they are at work and during daytime they are sleeping. If not sleeping the workers might be awake at fewer hours during daytime and in most cases during the day the members of their families who include the children and spouse are either at school or places of work respectively. This leads to less interaction time for the shift worker with his family and this result to loneliness and feeling of isolation.

For nurses this can very dangerous due to the safety concerns associated with this. The known cause of accidents and incidences can not be entirely blamed on disorientation of the circadian rhythm but the interference of the rhythm can affect the levels of concentration, motivation and the reaction time and mostly this is during the night shifts. This can result in a high increase in the rate of injury from accidents and carelessness putting the patient in danger and also the worker who in this case is the nurse.

Lack of sleep causes decline in performance normally experienced at certain times during the day. The worker who has been deprived of sleep is unaware that his or her performance has deteriorated. It has been proved that the optimum mental performance of workers occurs between 2 and 4 p.m with the maximum general awareness being between 1 and 7 p.m. The lowest performance levels are between 3:30 and 5:30 a.m which is the time the night shift workers are on duty. Thus the night shift workers are not only fatigued but also work during the times which they are at their lowest level of performance.

Code: Sample20

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