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

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Presentation on theme: "Shift Work Or: What time is it anyway? Warren Silverman MD Medical Director ACCESS HEALTH SYSTEMS."— Presentation transcript:

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

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

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

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

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

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

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

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

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

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

12 Longer rotations (3-4 weeks) may allow better adaptation to shift 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 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 an 8 hour shift = 16 hours to do everything else and sleep If a 12 hour shift, only 12 hours to do everything else. 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 Family duties do not decrease no matter the shift time leading to less sleep and rest Fatigue is cumulative Fatigue is cumulative

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

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

17 Circadian Rhythm

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

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

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

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

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

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

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

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

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29 Night workers have a drop in alertness at 2-4 AM 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 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 Mild sleep disruption may not have significant impact Cumulative increasing each night Cumulative increasing each night Disordered sleep is compounded by circadian dysrhytmia 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. 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 changes in several natural body rhythms of hormone secretion Melatonin Melatonin cortisol cortisol thyroid-stimulating hormone thyroid-stimulating hormone leptin leptin Prolactin Prolactin growth hormone. growth hormone.

32 What happens if we remove cues and disturb the internal clock? Desynchronosis: Desynchronosis: Core body temperature and digestive secretions may remain near daily mean levels Core body temperature and digestive secretions may remain near daily mean levels Entrainment Entrainment When we try to regain our rhythms with light dark cycles 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 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 Sleep disturbance Short term fatigue Short term fatigue Irritability Irritability Loss of Appetite Loss of Appetite Judgment alteration Judgment alteration

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

35 Two physiologies most critical to work and safety are core body temperature and sleep/wakefulness 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) 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 Phase delaying: places less strain on the human internal clock Higher worker satisfaction Higher worker satisfaction Fewer health complaints and work schedule complaints Fewer health complaints and work schedule complaints 20% increased productivity c/w phase advanced shifts 20% increased productivity c/w phase advanced shifts

38 Counter clockwise Phase advancing: 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) 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 25% of workers may not adapt

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

40 Sleep stages

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

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

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

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

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

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48 Health Effects Immediate Long term

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

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

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

52 Cardiovascular problems Increased incidence of ischemic disease Increased incidence of ischemic disease Elevated triglyceride levels in phase advance workers Elevated triglyceride levels in phase advance workers May be related to disturbance of circadian blood pressure and pulse rhythms May be related to disturbance of circadian blood pressure and pulse rhythms Substance abuse more likely in shift workers 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 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. Recent studies have found deterioration in cognitive ability in shift workers vs. non shift workers. This increases with duration of exposure This increases with duration of exposure The effect seems to diminish 4 years after discontinuation The effect seems to diminish 4 years after discontinuation

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

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

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

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

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

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

63 Making an Impact Strategies to WAKE UP

64 Administrative Controls 1. Limit shift work to essential jobs 2. Schedule toughest most dangerous tasks for early in the shift. Less demanding tasks for later in the shift 3. Avoid scheduling demanding or dangerous tasks at the beginning of an early morning shift

65 1. Tailor supervision: 1. Extra supervision between 3:30 AM and 5:30 AM 2. Younger workers have more accidents at the start of a shift following weekends 3. Older workers have more accidents at the end of a shift. 2. Supervise inexperienced workers more closely until they learn their job

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

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

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

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

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

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

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

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

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

76 Provide worker education and instruction Treat shift training like Hazcom Treat shift training like Hazcom Talk about health and safety difficulties Talk about health and safety difficulties Emphasize performance and accident risks Emphasize performance and accident risks Teach employees to recognize social and family problems 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 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 control shift work hazards and methods that can be used to do so. How to minimize the effects of shift work on themselves How to minimize the effects of shift work on themselves

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

79 Eat nutritious meals Eat nutritious meals Keep a regular eating routine Keep a regular eating routine Select foods high in carbohydrate rather than heavy fatty high protein meals before sleep 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 Family and friends should be made aware of the potential harmful consequences of shift work Adjust family and social life to maximize interaction Adjust family and social life to maximize interaction Maintain physical fitness Maintain physical fitness Learn strategies to remain awake at work Learn strategies to remain awake at work

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


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