1. Or: What time is it anyway?
Warren Silverman MD
Medical Director
ACCESS HEALTH SYSTEMS
Shift Work
Or: What time is it anyway?

2. What is Shift Work?
Regularly scheduled work outside of the normal daytime working hours of 7AM-6PM
Permanent night shifts
Afternoon or evening shifts
Shifts beginning before 6AM

3. Condensed work weeks with extra long weekends
Variable or rotating shifts
Day to evening or day to night
May change weekly or monthly

4. Why do we need shift work?
Critical services on 24 hour basis
Police, fire, military, healthcare, utilities, transportation,
A production process > 8 hours or continuous
Expensive machinery that must be used continuously to be profitable
Support services for other shift workers
Convenience

5. Who does shift work? Men do more night and rotating shifts
Women do more evening and part time work
Younger > Older workers
African-American > Caucasian
Single > Married
Single Mothers > Married Mothers
In 2 job married couples ¼ - 1/3 have at least one shift worker

7. 20 Million Americans do shift work ; 26% of men, 18% of women
Drop out rate: 20% at year 1; 33% at 2 years
Tolerance declines with age
Cumulative effects
Decreased physiological reserve > 40

8. Factors describing shift
Permanent (fixed) or rotating
How long?
How many days before a rest day
How many rest days on a “weekend”
Overtime?
Length of rest between shifts
Is there rest during shift
Is Schedule regular and predictable

9. Permanent Nights
Most permanent night workers never really get used to the schedule
Many nights they feel tired and sleepy
Fatigue because of return to day hours on days off
Family and friends active during the day
Errands and chores during the day
Sleep less during the day

10. Rotating Shifts Can never adapt to a set work schedule
Used to be more “fair” to all workers
Rotating shift workers have more complaints than others about physical and psychological health
Special Risks

11. Special Features Speed Direction
The number of consecutive days before a shift change
Direction
Forward or clockwise (day-evening-night)
Reverse (day-night-evening)

12. Longer rotations (3-4 weeks) may allow better adaptation to shift
Shorter (1-2 days) allows no time to get used to night shift, but can get through it quickly to get to rest day. Used more in Europe than US

13. Work-Rest Ratios
If an 8 hour shift = 16 hours to do everything else and sleep
If a 12 hour shift, only 12 hours to do everything else.
Family duties do not decrease no matter the shift time leading to less sleep and rest
Fatigue is cumulative

14. Unpredictable schedules
Health care workers with emergencies or covering call ins
A factory breakdown or last minute rush order
A last minute “call board” assignment to move an order
Being on call and getting called in (Doctors do know about this!)

16. How does the body work Internal Biological Clock Circadian rhythm
Regulated by sunlight and darkness

17. Circadian Rhythm

19. Circadian Rhythm Different body functions vary during the 24 hour day
Metabolism (energy from food) is greatest in the afternoon to evening
Most people most alert 4-6 PM and most sleepy 4-6 AM
Personal differences between people

20. Circadian body rhythms
Hormone and gastric secretions
Bronchial reactivity
Blood Pressure
Sexual arousal
Anxiety
Work performance
Metabolic Rate
Short term memory
Family interactions

21. The body has a natural cycle of 25 hours
Internal and external factors synchronize us to a 24 hour day
The internal clock is located in the suprachiasmatic hypothalmus

22. External clues “Zeitgebers”
Light/Dark cycle
Timing of meals
Social interactions
Actual time clock

23. Sleep ( Not now!) Night workers get the least sleep (6.6 hours)
Evening workers get the most sleep (7.1 hours)
Day workers get medium amounts (6.7 hours)
Rotating workers sleep the least of all.

24. Sleep during the day is usually 2-3 hours shorter
It is lighter sleep and more easily disturbed by noise
There are more activities and noise during the day

26. Sleep Sleep after night work Delta Sleep
Shorter, less satisfying or refreshing
Delta Sleep
Repair and Maintenance functions

27. Sleep loss makes it easier to fall asleep at inappropriate times
Will decrease concentration
Increase accidents ( driving, dangerous machinery)
Sleep can occur in short episodes lasting a few seconds without even realizing it. Very dangerous time.

29. Night workers have a drop in alertness at 2-4 AM
Accidents at 3 Mile Island, Bhopal, Chernobyl, and the Exxon Valdez oil spill each occurred between midnight and 4 AM

30. Sleep deprivation
Mild sleep disruption may not have significant impact
Cumulative increasing each night
Disordered sleep is compounded by circadian dysrhytmia

31. Sleep Deprivation
Six days of restricted sleep (4 hours per 24-hour period) caused changes to the sleep architecture similar to the changes seen in people suffering from depression.
changes in several natural body rhythms of hormone secretion
Melatonin
cortisol
thyroid-stimulating hormone
leptin
Prolactin
growth hormone.

32. What happens if we remove cues and disturb the internal clock?
Desynchronosis:
Core body temperature and digestive secretions may remain near daily mean levels
Entrainment
When we try to regain our rhythms with light dark cycles
Different physiologies may entrain at different rates and we may lose the normal phase relationship of one to another

33. Signs of desynchronosis
Sleep disturbance
Short term fatigue
Irritability
Loss of Appetite
Judgment alteration

34. What does The Dark do? Triggers changes leading to sleep
Dropping blood pressure
Dropping heart rate
Dropping breathing rate
Dropping temperature
Slowed digestion

35. Two physiologies most critical to work and safety are core body temperature and sleep/wakefulness

36. Rotation
While forward rotation works better with circadian rhythms of the body, reverse rotation is more common in the US (workers pick up an extra “day off” going from night to evening)

37. Clockwise shift rotation
Phase delaying: places less strain on the human internal clock
Higher worker satisfaction
Fewer health complaints and work schedule complaints
20% increased productivity c/w phase advanced shifts

38. Counter clockwise Phase advancing:
For every hour of advancement a full day is needed for entrainment (ie: phase advancement to an earlier shift every 7 days necessitates a week or longer to adapt after each rotation)
25% of workers may not adapt

39. Other observations Air travel:
Entrainment is much easier westbound than eastbound
“Night owl” type personalities adapt better to night and rotating shifts than “morning larks”
Rotation every 21 days results in 70% fewer complaints than every 7 days

40. Sleep stages

41. Stage 1 Initial part of sleep 10-15 minutes Slow rolling eye movements
EEG = Alpha waves
If awakened during this phase, will deny sleeping

42. Stage 2 Largest part of sleep @ 50% Infrequent or absent eye movement
EEG = occasional sleep spindle bursts
Deprivation of this stage may lead to total sleep loss
Not usually “made up” after sleep deprivation

43. Stages 3 & 4 Slow wave sleep (SWS): deep Muscle tone; variable
Arousal; difficult
EEG: High voltage; Delta waves
Important to body repair
Not as susceptible to circadian factors

44. REM After 1-2 hours Paralysis of muscles with occasional twitches
Body loses some thermoregulatory ability
Heart rate and blood pressure very variable
Restorative and dream sleep
Important for psychosocial adjustment and development
Greatly influenced by circadian factors

46. Cycling between stage 4 and REM
Increased with caffeine
REM suppressed with alcohol
Sedatives increase stage 2 non restorative sleep
Older less SWS, more frequent awakenings and less sleep time
Younger greater frequency and longer REM intervals

48. Health Effects
Immediate
Long term

49. Health Hazards Gastrointestinal Problems Cardiovascular problems
Sleep and stress related disorders
Drug and Alcohol use
Risks from prolonged exposure to chemical and biological substances and other hazards
Effects on pregnancy

50. Digestive Increased incidence of ulcers.
Often eat at night when digestion and other body functions are slowed down
May eat less nutritious foods at night (snack foods)
Drink more caffeine products at night

51. GI Upsets 75% of night workers vs. 20% of day workers Complaints
Loss of appetite
Constipation
Dyspepsia
Heart burn
Abdominal pain
flatulence
Many problems may not show up until years later
Reasons
Poor food quality
More caffeine
More alcohol
More tobacco
Used to keep awake

52. Cardiovascular problems
Increased incidence of ischemic disease
Elevated triglyceride levels in phase advance workers
May be related to disturbance of circadian blood pressure and pulse rhythms
Substance abuse more likely in shift workers

53. Hypertension
Shift workers were found to have approximately 25% greater chance of developing significant hypertension than non shift workers

54. Cognitive Ability
Recent studies have found deterioration in cognitive ability in shift workers vs. non shift workers.
This increases with duration of exposure
The effect seems to diminish 4 years after discontinuation

55. Psychological Shift workers demonstrate:
More depression and despondency
More likely to use psychotropic drugs or require hospitalization
Will have magnification of underlying depression or bipolar disorders
Circadian rhythm disturbance may be a cause for depression

56. Social Risks Number 1 problem: missing family and friends
Would rather loose sleep than miss social opportunities
Some activities are flexible ( ie: gardening, woodworking, fixing cars)
Some are not (clubs, team sports, childcare, school activities)

57. Social Impact Increases Divorce Family violence Social Isolation
Sexual dysfunction
May affect women more than men

58. Circadian rhythm related issues
Peak bronchial reactivity between 4-7 AM
Asthma may be worse in workers exposed to irritants
Shift work increases glucose levels in insulin dependent diabetics.
One study shows a 35% increased risk for developing diabetes
Sleep deprivation lowers seizure threshold
Increases frequency of migraines
The absorption, excretion, metabolism and peak effect of medications is affected by circadian rhythms

59. Colorectal Cancer
data suggest that working a rotating night shift at least three nights per month for 15 or more years may increase the risk of colorectal cancer in women 35%
Shorter durations also have increased risk
This may be due to the suppression of melatonin production with nocturnal light exposure. Melatonin has anti-cancer properties

60. Breast Cancer
Attributed to inhibition of melatonin production by light exposure during the night

61. Shift Work Sleep Disorder
Circadian Rhythm disruption
Insomnia
Disrupted sleep schedules
Reduced performance
Difficulties with personal relationships
Irritability/depressed mood
Sleep apnea 11.6% vs 5% in general population

62. Increased accidents To and from work Microsleeps Decreased vigilance
Alert to suddenly severe fatigue
Worse with monotonous tasks
Decreased vigilance
Lower performance
Higher error rates
20% increase in ergonomic workers compensation cases

63. Making an Impact
Strategies to WAKE UP

64. Administrative Controls
Limit shift work to essential jobs
Schedule toughest most dangerous tasks for early in the shift. Less demanding tasks for later in the shift
Avoid scheduling demanding or dangerous tasks at the beginning of an early morning shift

65. Tailor supervision:
Extra supervision between 3:30 AM and 5:30 AM
Younger workers have more accidents at the start of a shift following weekends
Older workers have more accidents at the end of a shift.
Supervise inexperienced workers more closely until they learn their job

66. Encourage good eating habits at night
Encourage good eating habits at night. Encourage light meals that are nutritious and easy to digest
Allow adequate meal and rest breaks
Have good emergency plans in place for odd shifts (nighttime emergency responders may be fewer than day)

68. Odd Shift Out Compressed workweek: Pros: 3-4 days of 10-12 hour shifts
More time off and between work schedules
More opportunities for family and social activities

69. Cons: Increased fatigue Decreased performance by the end of the shift
Daily exposure to chemical, biological and physical hazards my be increased
Some families may have trouble arranging childcare or eldercare

70. Permanent afternoon, evening or Night shift
Pro: More time to adjust
Con:
Disruptive to social life
Permanent night workers may accumulate a greater sleep deficiency over time

71. Rotating or Variable shifts
Length of rotation:
Workers rotated to a new shift schedule too rapidly or without sufficient break may have trouble functioning

72. Speed of rotation
Longer rotations of days may allow more time to adjust.
Circadian rhythm may require 3 weeks to fully adjust to a new shift
Mental functions adjust more rapidly
More trouble with the first 4 shifts
Faster rotations of 2-3 days do not allow for circadian rhythm adjustment
Faster rotation allows workers to get through the more difficult night shift rotation quicker

73. Direction of the rotation
Clockwise rotation from morning to afternoon to night causes fewer problems than the reverse order

74. Engineering controls Reduce night traffic, noise and distractions
Be aware of hazards. Calculate toxic exposures based upon shift duration (i.e.: 8H TWA vs. 12 hour shift)
Promote alertness:
Keep area brightly lit
Reduce glare and reflective surfaces
If feasible, allow workers to play music that will keep them awake

75. Maximizes safety and health controls
Good ventilation
Temperature control
Machine guarding
Avoid isolating workers. Communicate often
Provide food preparation areas, rest areas, consider and exercise facility

76. Provide worker education and instruction
Treat shift training like Hazcom
Talk about health and safety difficulties
Emphasize performance and accident risks
Teach employees to recognize social and family problems

77. They should know….
How to recognize health problems which may be related to shift work
How to control shift work hazards and methods that can be used to do so.
How to minimize the effects of shift work on themselves

78. They can do this by… Protecting their sleep periods
Maintaining regular rest and wake routines
Avoid exercising for 2 hours before going to bed
Keep light out the bedroom
Disconnect the phone
Maintain a quiet sleep area

79. Eat nutritious meals
Keep a regular eating routine
Select foods high in carbohydrate rather than heavy fatty high protein meals before sleep

80. Family and friends should be made aware of the potential harmful consequences of shift work
Adjust family and social life to maximize interaction
Maintain physical fitness
Learn strategies to remain awake at work

81. One last note: Modafilin aka Provigil
Sept 2003: FDA advisory panel recommended use for shift work sleep disorder
Different mechanism than amphetamines
Well tolerated
Memory improving
mood brightening
No jittery feeling
?anxiolytic