Shiftwork and Health: optimal timing of meals and physical activity

Lead Research Organisation: Liverpool John Moores University
Department Name: Sport and Exercise Sciences

Abstract

Many people now work at unusual hours of the day. Shift-work is no longer restricted to heavy industry but is now more common in E-commerce and telesales occupations to meet the need for 24-hour services. Shift-work is associated with greater health problems (e.g. chronic fatigue, gastro-intestinal and cardiovascular problems) than normal 9am-5pm day-work. It is unclear whether these problems are due to disturbances of the body clock and/or a decreased opportunity to adopt the desired amount and timing of lifestyle and social factors. With more than 20 years experience in researching this area, the possession of new facilities in our shift-work simulation unit, as well as a history of field-based research, the Chronobiology Research Group at Liverpool John Moores University will address these gaps in knowledge. We will explore such questions as, how does shift-work interfere with physical activity and eating habits? How does prior exercise influence metabolic responses and performance during a night-shift? What are the longer-term acceptability and the health consequences of a physical activity/dietary intervention programme? A qualitative component to the project ensures that shift-workers inform the research process throughout. Research findings will be disseminated, as they emerge, to employers and individual shift-workers.

Technical Summary

About 20% of the European workforce comprises shiftworkers in order to ensure that society?s needs for 24-hour services, process industries and emergency cover are met. We aim to explore the gap in health equality between shiftworkers and dayworkers and focus on the NPRI key research areas of ?diet and nutrition? and ?physical activity?. We will identify the most appropriate timing and composition of such interventions for reducing shiftworkers? problems (chronic fatigue, gastro-intestinal and cardiovascular disorders). The major novel methodological angle to this project is the combination of quantitative and qualitative research strategies. Two research assistants will complete three research phases;

(i) A survey of shiftworkers? dietary and physical activity habits.
Fifteen hundred participants will be sampled in a stratified random fashion. Confidence intervals will be calculated for the binary and Likert scale type responses, which will be compared between shiftwork factors. Qualitative data will also be collected through unstructured interviews with shiftworkers and their families.

(ii) Four controlled experimental interventions on participants living in our shiftwork simulation unit.
Twenty shiftworkers will be recruited for each of the 4 experiments. The exact interventions will be informed by the results of phase (i), but will involve the timing of physical activity (activity taken either before or after the workshift), the intensity of activity (either a relatively short 30-min bout of intense exercise or a relatively long 1-hour bout of moderate exercise), the timing of meals (the main meal of the day taken either before or after the workshift) and the content of food intake during a shift (food that matches typical content during daywork and food that matches typical content during nightwork). Likert scale ?acceptability? responses will be compared between repeated simulated shifts and between the various interventions.

(iii) A field-based intervention study on health outcomes over an 18-month period.
One hundred participants will be recruited for each of two intervention groups and a control group. The primary outcome measures to be investigated in this phase are cardiovascular health measures, frequency data relevant to the incidence of gastro-intestinal and menstrual cycle disorders over the study period and subjective scales to measure fatigue and sleep disturbance. Qualitative data will be generated (through interviews and focus groups) that are relevant to social and family conflict issues.

When this project is complete, employers and health promotion experts would gain ergonomic data to guide shift-work arrangements and promote optimum work-life balance of their employees.

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