Gardaí, security staff, doctors and even journalists have been working shifts for generations - but technology means irregular hours are now part of a growing number of occupations.
The downside of shift work is not just disruption to sleep but poor diet and weight gain.
Amanda Ursell, who is a visiting fellow at Oxford Brookes University, says that although there is a lack of scientific research looking into the area of shift work and diet, there is some data suggesting that sticking as closely as possible to normal daytime patterns helps. Here are some of Ursell's suggestions from Healthy Food magazine:
* Eat breakfast between 6am and 10am. Although this may be at the end of a shift its best to eat before your daytime sleep to avoid waking due to hunger;
* Avoid a large, heavy meal within two hours of sleep;
* Have lunch between noon and 4pm;
* Save dinner for between 5pm and 10pm. You don't have to have a full meal. A healthy sandwich followed by yogurt and fruit may suit.
Leaving this meal as late as possible within this time-frame means you have the best chance of getting through the night without grabbing something high-calorie. If this does not fit in with your schedule, choose foods that keep concentration and energy levels up, such as fresh fruit and salad, wholemeal bread or boiled eggs. She also stresses the need not to neglect exercise and suggests a diary.
Health & Living