Shift Work

Shift work is a fact of life for many us up here. The resource based industries we work often require that we do extensive periods of shift work.

Before I get too much farther I should define what shift work is. Shift work usually means regularly scheduled work outside of the normal daytime working hours of 7:00 A.M. to 6:00 P.M. It can include condensed work weeks, with extra long workdays or variable or rotating shifts that change work times from day to evening or day to night. The change may occur weekly or monthly.

The biggest effect of shift work on employees is sleep. Our body has a natural cycle or rhythm, known as our ?circadian rhythm? it tells us when to wake up and when to go to sleep. The biggest regulators of this clock are sunlight and darkness.

Normally, darkness triggers changes in the body that lead to sleep. When falling asleep, the body?s blood pressure, heart rate, breathing rate and temperature drop. Digestion also slows. Certain repair and maintenance processes occur during a phase of sleep known as delta sleep. It takes the body some time to reach delta sleep. Subsequent phases of sleep are important to psychological well-being. Working during normal sleep hours affects the body?s ability to digest food, rest, restore and repair itself and may affect a person?s sense of well-being.

Shift workers try to sleep during the day. Normally, daylight signals the body to prepare for activity. As the body wakes up, blood pressure, heart rate, breathing rate and temperature rise. The person feels more alert. It is harder to get to sleep, and to get sufficient sleep, when the body is prepared to be awake. Trying to sleep in short spurts may shorten the particular phases of sleep needed for body maintenance, repair processes and psychological well-being.

Besides sleep, the next biggest health hazard shift workers face are stomach problems. In addition some workers may eat less at night while others may overeat and may eat less nutritious foods on night shifts (Often there is less access to nutritious meals at night and workers may rely on snack foods with a high fat content). Finally workers may drink more coffee to stay alert at night and heavy coffee consumption increases the risk of developing ulcers.

There are a number of other health issues related to shift work, but scientist are still studying them. So far though they are finding links between shift work and cardiovascular problems, sleep and stress related disorders, drug and alcohol use, asthma, diabetes, epilepsy and depression may all be made worse by shift work, but most of this research is still either inconclusive or still in the early stages of being conducted.

Another major impact of shift work is the effect on family and friends. Workers are often at work when regular social activities are scheduled and at home when others are at work. Therefore, they may spend less of their time-off involved in social or recreational activities. Fatigue may also prevent shift workers from enjoying those recreational and social activities that they are able to participate in.

In terms of safety most night workers complain of sleepiness. Sometimes they fall asleep on the job. Performing tasks that require alertness may be worse at night, when workers? bodies are prepared for sleep. Performance levels appear to be lowest between 3:30 A.M. and 5:30 A.M. An accumulated sleep deficit from prolonged shift work can decrease a worker?s level of performance and alertness, regardless of the time of day.

Working extended shifts can also cause poor performance and decreased alertness. Performance deteriorates on extended work shifts where the work is physically or mentally demanding. Perception and decision-making ability may also be affected on extended shifts. These factors can contribute to accidents and injuries. However, higher incident and injury rates have not been clearly linked to shift work because shift work is only one of many factors contributing to incidents and injuries.

So how can we control these hazards associated with shift work. Well, for starters we can limit shift work to essential jobs or we could organize workloads so that the toughest and most dangerous tasks are completed early in the shift. Schedule less demanding tasks for late in the shift.

You can adjust the workload during the shift to prevent boredom. Definitely you should ensure supervision is effective, particularly when accidents are more likely. Supervision is very important between 3:30 A.M. and 5:30 A.M. when performance is at its lowest. Younger workers appear to have more accidents at the start of a shift following a weekend. Older workers seem to have more accidents at the end of the shift.

Shift scheduling is a factor in their safety, the different types of schedules each have their pro?s and con?s. Compressed work week ? These shifts usually involve three to four days of 10 to 12 hour shifts they allow time for off work activities between shifts but not much time to adjust to the shift while on it. Permanent afternoon, evening or night shifts. These shifts allow workers time to adjust, but are disruptive to their social lives. Finally, rotating or variable shift schedules of different lengths. These shifts are the most common type of shift work they give a good variety but again there may be sleep deficit issues here.

As i said rotating shifts are the most common and adapting to them can be affected by the length of the break before changing to a new shift schedule, the speed of the rotations and the direction of the rotation (Shifts rotating clockwise morning, afternoon and night) cause fewer problems than those rotating counter clockwise.

Another important factor in shift work is the workplace design. You can use workplace design to improve conditions for shift workers by, reducing night traffic, noise and distractions or designing work areas to reduce physical, chemical and biological hazards and limit exposures to harmful chemical and biological substances

Try ensuring that the work environment promotes alertness. Keep work and traffic areas brightly lit. Reduce glare and reflective surfaces. If feasible, allow workers to play music that will keep them awake.

I think it is also important to educate your workers about the hazards of shift work and their significance. For example symptoms of poor health often appear and are more pronounced during the first year of shift work. Workers who are about to begin shift work for the first time should be encouraged to consult a physician, particularly if they have a chronic illness or are on long term medication.

Well that is just a small bit of the advice out their on shift work, but I hope it helps you. If you want more information just search it on the net or give me a shout.

Stay safe and I will talk to you again next week.


Rob Mandeville is a Safety Advisor and Auditor at Action Health & Safety Services. He has his OH&S certificate from the UofA, and is currently studying for his CRSP ( Board of Canadian Registered Safety Professional) exams. If you have a question about health and safety or an idea for an article you can reach him at