Diet and Nutrition for the Shiftworker

 

Science behind the problem - digestive problems

Adapted from Shiftwork and Health, European Studies on Time, European Foundation of Living and Working Conditions.

After sleep problems, gastrointestinal disorders are the most frequently recorded symptoms among shiftworkers. As humans we are programmed to digest more efficiently during the day than at night.

Up to 75% of people who work some nights complain of appetite disturbance, bowel problems, dyspepsia, abdominal pains and heart burn, compared to approximately 25% of day workers.(Rutenfranz et al 1981).

The prevalence of peptic ulcers, the most severe illness, has been estimated to be from 2 to 8 times higher amongst shiftworkers compared to day workers.

Possible causes of indigestion

Shiftwork interferes with meal times. Meal times are one of the zeitgebers (external time queues) that can help to stabilize the body clock. The most common hours of starting and ending shifts mean that usually one of the two main meals almost always has to be eaten either:

  1. at home but earlier than the normal time
  2. at work where food is often heated up, or, poor quality food is consumed from vending machines.

During night shifts, when canteens are generally closed, many shiftworkers have no choice other than to eat pre-packaged food which is often laden with salt and or sugar. They also are more inclined to increase the intake of stimulating drinks (e.g. coffee, tea) and alcoholic beverages as well as smoking tobacco.

Eating habits of shiftworkers

Leonard (1996) reports that he found in a survey that lunch is skipped by 25% of night workers probably to avoid interrupting their day sleep. In addition 16% of the workers drank more coffee at night, whilst 13% smoked more. About 50% of companies in Leonard's study offered fries (chips), every day. This does not mean that the same people eat chips, but it is a reflection of the food that is readily available.

Whilst there are some exemplar New Zealand companies to be found in terms of serving high quality, nutritional food, we also notice that many companies offer what is eaten by the greatest number of people irrespective of the nutritional quality.

Interaction between sleep and digestive problems

Sleep and digestive problems may also interact. For example excessive use of caffeine can cause digestive disorders and whilst help keeping the worker alert at night, it also makes good quality sleep more difficult to achieve. For some people the digestive system is more prone to problems when the person is sleep deprived.

Another area of interaction between sleep and digestion is to do with the production of the hormones that influence apettite.

Some of us, when awake in the middle of the night, feel an urge to visit the kitchen. This could explain results of previous studies that have shown a link between short sleep duration and high body mass index (BMI). But a study by Emmanuel Mignot and colleagues suggests that it’s not just the additional snacking opportunities that make short sleepers more likely to be overweight. Recent studies show that sleep deprivation in laboratory settings can cause a decrease in serum levels of leptin, a  hormone known to control appetite.

Investigating this further Mignot studied the levels of various hormones known to regulate appetite and energy expenditure under “real life” conditions.

They used the Wisconsin Sleep Cohort Study, an ongoing longitudinal study of sleep habits and disorders in the general population.

The study began in 1989, when researchers mailed state employees aged 30–60 years a survey on sleep habits, health, and demographics. Mail surveys were repeated at 5-year intervals, and some of the respondents were recruited to sleep a night in the laboratory and undergo various tests. A number of participants were also asked to keep a sleep diary for 6 days. The study has already shown connections between sleep apnoea and hypertension, and between menopause and sleep-disordered breathing.

For their study, Mignot and colleagues measured sleep duration, BMI, and pre-breakfast blood hormone levels in 1,024 participants.

Consistent with previous studies, they found that in individuals who sleep less than 8 hours (74% of all participants), BMI was inversely proportional to sleep duration. In otherwords, the less individuals slept, the greater their BMI. In addition, short sleep was associated with low leptin and high ghrelin levels (ghrelin is a hormone thought to stimulate food intake). These hormonal differences are likely to increase appetite, which could be responsible for the increased BMI in short sleepers.

These findings could explain, at least in part, why societies in which excess calories are much easier to come by than a good night’s sleep are more prone to obesity.

Conclusion

It is clear that digestive problems are a common health complaint amongs shiftworkers. The problems however are not universally found. Positive intervention can greatly improve the situation. It is not easy to change peoples eating habits but some changes such as following healthy eating guidelines and reviewing such things as canteen menus and educational programmes have the potential to have a sustained positive result.

Bibliography

  1. Rutenfranz, J., Knauth, P. and Angersbach, D., ‘Shift work research issues’, in L.C. Johnson, D.I. Tepas, W.P. Colquhoun and M.J. Colligan (eds.), The twenty-four hour workday: Proceedings of a Symposium on Variations in Work-Sleep Schedules, U.S. Department of Health and Human Services, 1981, 221-269.
  2. Léonard, R., Health and working time, Dublin, European Foundation for the Improvement of Living and Working Conditions, 1996.
  3. Taheri S, Lin L, Austin D, Young T, Mignot E.,  Sleep Duration Affects Appetite-Regulating Hormones. PLoS Med 1(3) 2004: e68 doi:10.1371/journal.pmed.0010068

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