Dr Kerryn Phelps, Health Editor, Channel 9 'Today'

GRIMSHAW: Before we talk about what shift work does, let's talk about how the body normally responds to, say, daylight and darkness.

PHELPS: The body has what is called a circadian rhythm, which means that all of the hormones, and all of the chemicals in the body have a rhythm, that goes up and down, depending on the time of the day or night. And, for example, there is one particular hormone called Melatonin, which is found at the base of the brain. It's produced by a little gland called the Pineal gland, at the base of the brain, and as soon as it becomes dark, the Melatonin is produced in larger quantities. If you are looking at body temperature, for example, that will go up towards the late afternoon, and will dip down during the night. Similarly, hormones like …… have an ebb and flow during the 24 hour period. That's the stress hormone, so if you're having shift work, and it's not necessarily regular shift work, then it actually throws out the body's chemicals, and that can have effects on health. And particularly, because even if people do a regular type of shift work, like every day, Monday to Friday, they are doing particularly unusual hours, where they're working through the night time hours. They might go back to working the way everybody else does, either the following week, or on the weekends, where they have their time off. They get up in the morning, and go to bed at night.

GRIMSHAW: So your body never really knows whether it's day time or night time, or what it should be doing?

PHELPS: That's right.

GRIMSHAW: It can have an extraordinary array of effects, can't it, stomach problems, heart disease, mental health?

PHELPS: What's very interesting, is that there is a great deal of research now being done on shift work, and the sorts of health effects that they're showing are a lack of concentration, people have problems remembering things, slower reaction times at work, and that, of course, leads to increased risk of accidents. People can be tired all the time, and this can be, quite often, not because they're getting sleep at odd times, but because they're not getting enough sleep, and that's an issue. Irritability, of course. They can be susceptible to alcohol and drug abuse, because they may take drugs or use alcohol to get to sleep at the odd hours, and they can become depressed, and also weight gain or loss is a problem. That is probably a combination of hormones and the fact that, when people are working shift work, it's very hard to know when breakfast, lunch and dinner is.

GRIMSHAW: Yeah.

PHELPS: And it's out of sync with everybody else that they know.

GRIMSHAW: I guess that explains things like stomach problems, too. Why heart disease? And for women, women can have problems conceiving, they can have miscarriages, they can have premature birth, all attributed to shift work?

PHELPS: Yes. The research is showing that there are effects on women and the problems that you mentioned. There is also a report in today's press where it's been shown by two separate studies, that there is an increased risk of breast cancer in women who work shift work. Stomach ailments, as you said, more risk of abdominal pain, diarrhoea, constipation, that could be dietary related as well, but, interestingly, an increased risk of peptic ulcers, which may well be stress related as well. As far as heart disease is concerned, there appears to be an increased uptake of blood, fats into the blood, and that, of course, will increase risks of heart disease. And, of course, lack of exercise, because if people are working odd hours, it's very difficult for them to fit in exercise, and fit in regular, appropriate meals.

GRIMSHAW: If we can't do anything about our shift work, and particularly about our erratic shift work, how do we address the problem? Can we do it with relaxation techniques, with diet, that sort of thing?

PHELPS: I think it's really important if someone does shift work that they learn how to manage it. It's not simply a matter of just, you know, having a few beers to get yourself off to sleep. It's learning how to get to sleep by either meditating, relaxation exercises, making sure that your room is blacked out and quiet, if you are sleeping during the day, and that can be very difficult. Also making sure that you don't overdo alcohol, and that you do plan for some exercise every day, the same as you would if you were up and about in the daylight hours.

GRIMSHAW: Just a final question. Is it only for people who completely change their lives around, so work at night and sleep during the day? Or what about if you work into the night, or start working at the end of the night? I mean, at either end of the scale?

PHELPS: A bit like morning television.

GRIMSHAW: A little like that, a slightly selfish question, I must say.

PHELPS: If there is an abnormality, a shift in the cycle, your body can adapt. If you're doing that all the time, it's quite often, I think, more disruptive to somebody if they're like a nurse or a junior doctor where they might do a few days of night shift, and then they are off to a day shift the next few days. And it's very important that they not only work a reasonable number of hours - not the excessive hours that are expected of them - but also that when they have time off, that they have reasonable time between their shifts, and that they do sort of try to manage things like diet and exercise and getting enough actual quantum of sleep.

GRIMSHAW: Thanks, Kerryn.

PHELPS: Thanks, Tracy.

Ends