For 10 per cent of Irish workers, fighting their body clock is just another part of their working day. Michael Kellyreports
AROUND THE time the majority of us are crawling into bed at night, armies of workers in the health, transport, storage, hospitality and manufacturing sectors are just beginning their day's work.
For hundreds of years shift and night work has been used by industrialised countries to keep their economies operating 24 hours a day. In Ireland, roughly 10 per cent of workers (186,000 people) do regular shift work with men accounting for nearly 65 per cent of that figure.
The field of chronobiology (the study of biological rhythms) has established that shift work has potentially serious physiological and psychosocial consequences due to the disruption to the body's circadian rhythms.
Circadian rhythms are the changes in mental and physical characteristics that occur in the course of a day, controlled by the body's biological clock.
At its most basic level, the circadian rhythm dictates that human beings tend towards wakefulness during the daytime and sleep at night.
"During the middle of the day your body wants to be active while during the night your body wants to be asleep," says Jim Waterhouse, professor of chronobiology at Liverpool John Moores University.
"This is not just due to our environment or the fact that it's dark at night and bright by day, but also due to our body clocks. Normally we keep these two essential rhythms - our body clock and our environment - in phase."
A good example of what happens when we disrupt the circadian rhythm is the experience of jet lag. "When we fly across time zones, say from Dublin to Hong Kong, we suffer from jet lag. We feel sleepy in the daytime and can't sleep at night.
"If you track physical, mental and hormone levels of a person suffering from jet lag, you will see they are impacted. But eventually if the person stays in that time zone, the feeling of jet lag will disappear because all of the environmental clues around say to the body clock that it's time to adjust."
While the body clock can adjust to a change in time zones, it never fully adjusts to night working, according to Waterhouse. "When the night worker leaves the workplace there are lifestyle and environment clues that confuse the body clock. The person is aware that they are the odd one out and are doing things differently from everyone else.
"They also tend to complicate things by trying to live 'normally' on their days or weeks off which puts the body clock out of sync again."
This problem, he says, is compounded by rotating shifts, because the body clock never gets a chance to adjust to a single schedule.
Sleep disorders are the most common result of this disruption - specifically difficulty in falling asleep, shorter duration of sleep and poorer sleep quality.
"What is observed is that night workers never feel fully alert at night and never sleep properly during the day. This is essentially chronic fatigue where they always feel tired, even when they are on their time off or on holidays."
In addition, laboratory studies have shown an association between disturbances in circadian rhythms and loss of attention, motivation, ability to concentrate, and a slowing of perceptual-motor processes.
Constant altering of the circadian rhythms can also place shift workers at excessive risk of involvement in accidents and injuries on the job.
Not surprisingly, the incidence of accidents in the workplace is much higher during the early morning hours (4am-6am) than at any other time of day.
PJ Gallagher is a nurse in the AE department of a major Dublin hospital and has been working shifts (including a week of nights once a month) for about 10 years.
"The first few nights are very hard. You are drinking a lot of coffee to stay awake. But as the week progresses it gets easier and then at the end of it, you are so used to sleeping during the day it's very hard to get back to normal," he says.
"A key problem for me is that I don't eat very well when I am on nights. I do a lot of snacking and comfort eating and I tend to buy microwave dinners rather than cooking. I suffer from heartburn and indigestion when I am on nights and my bowel function becomes more irregular."
Gastrointestinal problems such as indigestion, ulcers, gastritis and constipation are common among night workers.
"The gut is also in tune with the body clock," says Waterhouse. "It is interested in digesting food by day and taking a rest by night. But the night worker is eating at night when the digestive system should be resting."
While the prevalence of sleeping and gastrointestinal disorders among night workers is well documented, there is also increasing evidence to suggest that long-term night work could lead to more serious chronic illnesses.
"Night workers are more prone to cardiovascular disorders when compared with a person with a similar lifestyle who works days," says Waterhouse.
"It is not 100 per cent clear why this would be the case, but it is generally accepted to be because of the increased stress of living this type of life.
"This is particularly the case for workers who feel they have no choice but to work nights because they need the money or there are no alternative shifts available."
A loss of emotional wellbeing is also a common complaint among night workers. In a study of 900 electricity workers in Australia, Wallace, et al, found that shift workers reported higher levels of cigarette, coffee and tea consumption, and more frequent use of laxatives, sleeping pills, pain killers and cough medicine than day workers.
The interference with family life and the anti-social nature of shift working have a direct psychological impact, according to Health and Safety Authority (HSA) employment psychologist Patricia Murray. "You are working outside the norms of society and, consequently, your whole life becomes about work. In some cases, shift workers feel that they are not around people as much - they are asleep when everyone else is up so they feel that they are missing out on things. This can be very isolating and lonely."
PJ Gallagher describes the experience of nights as being akin to going away for a week. "I have been going out with someone for two years and I tell her not to pass any heed to what I say when I am on nights. I am definitely crankier and not as tolerant. You are just not yourself. I don't have a family so I am not being pushed to get up out of bed but some of the girls who I work with have kids so it's very hard for them."
So are there ways for employees to reduce the impact of shift working on their emotional health?
"They have to make extra efforts to incorporate social activity into their lives because it doesn't come as easily," says Murray. "They need to be constantly asking themselves: what am I not doing that society in general is doing? Could I meet people for lunch instead of dinner? Can I schedule in time for a walk before I go to work?"
There is also a considerable onus, she says, on employers to ensure that shifts are well designed.
"Shift work design should aim to include some element of normality. It's not good enough to say that a shift worker can do Saturday things on a Wednesday. They can't. So the shift design must give the worker a chance to do normal things, even if it's only occasionally.
"They should also have at least three weeks of visibility of their schedule so they can plan some social activity. They can say, next week I can get to the bank or bring the kids to school."
Tips that work
A good diet, regular meals and exercise during shift work will improve sleep quality, health and wellbeing.
Try to keep to a regular sleeping pattern and take steps to promote sleep - make sure the bedroom environment is favourable (ie cool, dark, free of noise). Avoid caffeine, 'energy' drinks and alcohol a few hours before bedtime.
Get at least 30 minutes of exercise per day, ideally before your shift starts.
Eat balanced and regular meals. Choose foods that are easy to digest such as pasta, rice, salad, fruit and vegetables. Avoid sugary and fatty foods. Drink plenty of fluids.
Have your largest meal after your day-time sleep, before starting the night shift. Have only a light meal in the middle of a night shift and before you sleep.
Avoid relying on stimulants to maintain wakefulness or sedatives to promote sleep.
Look after your social health. Maintain contact with friends and family. Plan social activities around your time off but do not be tempted to let them affect sleep time.