Professor David Koh MBBS, MSc, PhD, FFOM, FFOMI, FFPH, FAMS

1. Occupational Health Conference Muscat, 11-13 Dec 2006 Shift Work Professor David Koh MBBS, MSc, PhD, FFOM, FFOMI, FFPH, FAMS Department of Community, Occupational and Family Medicine Faculty of Medicine

2. Shiftwork • Done for hundreds of years • Numbers increased tremendously since invention of the light bulb (Edison) • 20-25% of all workers in developed countries do shiftwork • Occupations • transport, security, health care, essential services, continuous manufacturing processes

3. Shiftwork Any work outside normal 0800 hr to 1700 hr “regular” hours • Different types • double day • 3 shift systems • split shifts • day-and-night shifts • permanent shifts • irregular shifts • 8 hour vs 12 hour shifts • Forward vs Backward rotation • F: morning, afternoon, night • B: morning, night, afternoon

4. Circadian Rhythm Changes in body temperature, heart rate, blood pressure, metabolism, respiration, hormonal secretion, urine flow, absorption of drugs, etc. Activities increase in daytime (ready for action) and decrease at night (rest and recuperation) Circadian system “reset” by external synchronizers e.g. light/darkness, mealtimes Good health requires synchronicity between activity/rest cycle and human circadian rhythm

5. Circadian Rhythm in Body Temperature

6. Effects of Shiftwork Two things wrong with shiftwork: - having to work when supposed to sleep - having to sleep when supposed to be awake For some people, this can result in performance, health and social effects

7. Effect on Performance

8. Health Effects Short term disorientation, fatigue, health problems Longer term heart, gastrointestinal, sleep, psychological effects, effects on pre-existing illnesses Social Effects • - Interactions with family and friends • Lifestyle and community activities

9. Health Effects • Heart disease • Some studies show an increased risk of heart disease among shiftworkers • ? due to anxiety, sleep disturbance, lack of exercise, fatigue, potential for family conflict, diet, increased blood lipids, tobacco etc.

10. Gastrointestinal disease • Indigestion, heartburn, loss of appetite • Poorer diet ? at night, loss of appetite may cause increased snacking on junk food instead of a well balanced meal • Irregular meals, excess alcohol, caffeine, smoking

11. Effects on Pre-existing Illness e.g. Diabetes, Epilepsy, Peptic ulcers

12. Sleep Disorders Sleep quantity and quality affected, especially with night work Daytime sleep not as deep or refreshing Worse when room is not quiet, dark, comfortable Sleep Quantity Night shift – 4-6 hrs sleep Day shift – 7.5 hrs Evening shift – 8.5 hrs Sleep Quality Day sleep – less deep sleep (stage 3-4) Rotating shift < Permanent shift

13. Alertness and Accidents • - Fatigue affects alertness in many shiftworkers • 80-90 % of shiftworkers feel sleepy during night shift (?% nap!) • Some studies show increase (others do not) in accident rate • Tendency for more severe / serious accidents to occur

14. Exxon Valdez – 12.04 a.m. 24/3/89 Tanker with 1.3 million barrels of Alaskan crude Bhopal – 12.15 a.m. Dec 3 1984 Chernobyl – 1.23 a.m. April 26 1986

15. Psychological Effects • Shiftwork dislocates family life • Interferes with social contacts Less chance to participate in group activities As a result, some shiftworkers are irritable, moody, tired

16. Social Effects * Interactions with family and friends - Depends on age, marital status, children, hobbies, personal interests * Problems in establishing regular routines in daily activities, planning for family responsibilities and coping with physical and mental fatigue

17. Participation in clubs, sports and other organized activities may be difficult • Lack of regular social contact may cause feelings of isolation, loneliness Lifestyles and Community Activities

18. Shiftwork is Not Always Bad ! • * Not all effects are negative, advantages include: • More off days or off time • Fewer trips to & from work, less time wasted in travel • Shops, other amenities open during off work time • Greater freedom to plan leisure • More incentives, benefits

19. Shiftworkers are a self-selected group * About 10% to 15% of workers cannot tolerate shiftwork, and leave * About 10% to 15% of workers enjoy working in shifts * Majority cope with shiftwork well

20. Shift-friendly Workplaces * Scheduling and work environment Shift design and scheduling e.g. longer rest pauses, forward rotation Work environment - provision of amenities e.g. transport, food - work environment design e.g. lighting, first aid / health cover Pre-employment screening pre-employment screening may not be so useful, but a good opportunity to educate & advise

21. Shiftworkers Should : • Be aware of alertness levels • on different times of shift • on different days of shift • get enough sleep Time of Night

22. Is bad . . . . Hours of Sleep on Prior Night Successive Days of Reduced Sleep

23. Effect of Light on Alertness Level

24. Alertness Triggers to Alertness * sense of danger, interest or opportunity * muscular activity * time of day on circadian clock * sleep bank balance * ingested nutrients and chemicals * environmental light * environmental temperature / humidity * environmental sound * environmental aroma

25. Sleep Hints Nap 1-4 hrs before first night shift After the last night shift, take a short sleep first, then go to bed early that night Some people prefer other sleep patterns – see which best suits you Nutrition Regular eating patterns as far as possible Balanced, varied meals are important Timing of meals Exercise Physically fit people adapt to shiftwork better

26. Medications • Avoid excessive use of antacids, tranquilizers and sleeping tablets • Check with family doctor or pharmacist if you take medication during working shifts • Some drugs may cause drowsiness, some may have to be timed differently in order to account for absorption patterns and activity patterns

27. Family Solutions Must involve whole family Shift workers must understand social implications of shift work Social and family activities must be arranged to accommodate the schedules of the shift worker Use of time management strategies and spending quality time

28. Summary Types of Shiftwork Circadian Rhythm Effects of Shiftwork Health and Social Effects Shift-friendly Workplaces Scheduling & Work environment Pre-employment screening What Shiftworkers can do Alertness and Sleep Lifestyle: Nutrition, Exercise, Medications Family