fatigue management in shift work ness 2010 newton, ma christopher p. landrigan, md, mph director,...
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Fatigue Management in Shift Work
NESS 2010Newton, MA
Fatigue Management in Shift Work
NESS 2010Newton, MA
Christopher P. Landrigan, MD, MPHDirector, Sleep and Patient Safety Program, Brigham and Women’s HospitalResearch Director, Children’s Hospital Boston Inpatient Pediatrics ServiceAssistant Professor of Pediatrics and Medicine, Harvard Medical School
Disclosures and AcknowledgementDisclosures and Acknowledgement
Dr. Landrigan has served as a paid consultant to:1) Vital Issues in Medicine, developing an educational course for
physicians on Shift Work Disorder; this work was supported by a grant from Cephalon, Inc. to Vital Issues in Medicine.
2) In addition, Dr. Landrigan has received monetary awards, honoraria, and travel reimbursement from multiple academic and professional organizations for delivering lectures on the quality of inpatient care, sleep deprivation, resident performance, and safety.
• Some of the slides developed for this presentation were developed with the support of Vital Issues in Medicine
• Thanks to the Harvard Work Hours, Health, and Safety Group for providing additional slides
(Lisbon Falls, ME, 13 Jun 01) – Trucker Jorge Rosario of Orlando, FL, after being awake for 32 hours, fell asleep at the wheel of his tractor trailer, crashed, and killed Mark Leek, Pablo Jaramillo and Geraldo Perez-Guerrero while they were stopped at a red light on US 27 (1998). On 8 Jun 01, a Florida court sentenced Rosario to 15 years in a Florida State prison. The trial judge, in issuing the sentence, stated,
“…you decided to get behind the wheel. It’s like taking a shotgun and shooting into the crowd. There was a chance you took, and you lost big.” (Ledger, Lakeland, Fl.) … The three families settled lawsuits totaling $10 million against Rosario, Whirlpool Corp., GPC Driving Inc. and KENCO Logistic Services.
Case #1
(Source: Parents Against Tired TruckersPhoto courtesy of Florida Department of Corrections)
Case #2Case #2• Heather Brewster’s car was rear-
ended by a medical resident who had just completed a 36-hour hospital shift
• Brewster…– suffered massive brain injuries – was in a coma for weeks– became permanently disabled– was declared incompetent by
the courts Heather Brewster, pictured in 2002
Photo courtesy of the Brewster family; Story available at http://www.npr.org/templates/story/story.php?storyId=4512366
Who Works Shift Hours?Who Works Shift Hours?
Evening Night
Rotating Split
Irregular Other
Top Occupations
Shift Workers
(1000s)
% ofTotal
Force
Production 2021 24.4
Transportation & material moving 1900 28.5
Food preparation & serving 1568 40.4
Sales & related occupations 1464 15.2
Office & administrative support 1458 9.9
Health care practice & technical 1138 24.6
Protection services 1125 50.6
Management 612 9.8
Cleaning & maintenance 609 17.5
Personal care & service 542 28.1
Health care support 534 28.0
Installation, maintenance & repair 488 11.4
Construction & extraction 256 9.8
Community & social services 237 12.7
Arts, entertainment, media & sports 221 14.7
TOTAL 14,173 17.5
33%
22%
17%
20%
3%
5%
Data source: Bureau of Labor Statistics (2004) .Approximately 99.8 million workers >16 years. Available at: www.bls.gov/news.release/flex.t05/htm
Starting Times for Full-Time Workers26% of the U.S. Labor Force at Risk for SWD
Starting Times for Full-Time Workers26% of the U.S. Labor Force at Risk for SWD
Source: Bureau of Labor Statistics, May 2004 data; available at http://www.bls.gov/news.release/flex.t07.htm
Start time unknown: 1.5%
4:30AM
8:30AM
12:30 PM
4:30PM
8:30PM
12:30 AM
0.7%
8.6%
51.5%
6:30AM
2:30 AM
10:30AM
2:30PM
6:30PM
10:30 PM
15.6%
1.1%1.2%
3.1%
1.0%
1.1%
0.8%
1.3%0.2%
StartTime Varies
12.2%
Elevated risk for SWD
Day and evening shift workers
25.9%
72.6%
Unknownrisk
1.5%
• Biological Time of Day (circadian rhythms)
• Consecutive Waking Hours
• Night Sleep Duration
• Sleep Inertia
DETERMINANTS OF ALERTNESS AND PERFORMANCE
Courtesy of D. Weaver, Univ Massachusetts Medical School, Worcester, MA
Human Circadian Pacemaker in Suprachiasmatic Nucleus (SCN) of Hypothalamus
SCN
Core Body Temperature
Plasma Melatonin
Eye BlinkRate
Slow EyeMovements
Stage 1 Sleep
Figure 1
Relative Clock Time (h)8 16 24 8 16
°C
36.5
37.0
37.5
pm
ol/L
0
100
200
% o
f 5-m
in e
pochs
0
8
16
# p
er 30-s
epoch
5
10
15
Elapsed Time Awake (h)
0 8 16 24 32
0
1
2
3
Relative Clock Time (h)8 16 24 8 16
Karolinska Sleepiness Scale
3
5
7
Cognitive Throughput
30
45
60
Elapsed Time Awake (h)
0 8 16 24 32
Probe Recall Memory Test
0
2
4
ms
# o
f A
ttem
pts
# o
f corr
ect P
air
s
200
500
1000
6000
Psychomotor Vigilance Performance
more
tir
ed
mean reaction timemedian reaction time
10% slowest reaction time
10% fastest reaction time
Cajochen et al. Am J Physiol 1999 NTSB Study (SS1995/01)
02468
101214161820
1:00AM
3:00AM
5:00AM
7:00AM
9:00AM
11:00AM
1:00PM
3:00PM
5:00PM
7:00PM
9:00PM
11:00PM
Num
ber o
f Acc
iden
ts
Temporal distribution of fatigue-relatedsingle vehicle truck accidents
Performance Efficiency Over 24 HoursPerformance Efficiency Over 24 Hours
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Eff
icie
ncy
(M
ean
Z)
24:0003:00 06:00 09:00 12:00 15:00 18:00 21:00
Efficiency assessed in 3 studies by: 1) delays in answering phone calls; 2) errors in reading meters; and 3) time taken by spinners to tie broken threads.
Folkard S, Tucker P. Occup Med. 2003;53:95-101.
• Biological Time of Day (circadian rhythms)
• Consecutive Waking Hours
• Night Sleep Duration
• Sleep Inertia
DETERMINANTS OF ALERTNESS AND PERFORMANCE
0 10 20 30 40 50
-30
-20
-10
0
10
20
Hours of Wakefulness
Su
bje
cti
ve A
lert
ness
Co
gn
itiv
e T
hro
ug
hp
ut
Hours of Wakefulness
Devi
atio
n fro
m M
ean (
mm
)
-30
-20
-10
0
10
0 10 20 30 40 50
Devi
atio
n fro
m M
ean (
# a
ttem
pte
d)
Jewett et al., 2000
Hours of Driving
National Transportation Safety Board
Acute Sleep Deprivation and Performance
“...after [19] hours of sustained wakefulness (at 3 am) cognitive psychomotor performance decreased to a level equivalent to the performance impairment observed at a blood alcohol concentration of 0.05 %. ... After 24 hours of sustained wakefulness (at 8 am) cognitive psychomotor performance decreased to a level equivalent to the performance deficit observed at a blood alcohol concentration of roughly 0.10 %.” - D. Dawson and K. Reid, Nature 388: 235, 1997.
• Biological Time of Day (circadian rhythms)
• Consecutive Waking Hours
• Night Sleep Duration
• Sleep Inertia
DETERMINANTS OF ALERTNESS AND PERFORMANCE
Van Dongen et al. Sleep 2003
Chronic Sleep Deprivation and Performance
012345678
mean lanevariability (feet)
mean speedvariability (mph)
Light callLight call w / alcoholHeavy call w / placebo
“Heavy Call” and Resident Performance
p=0.06
p=0.01
Arnedt et al. JAMA 2005
• Biological Time of Day (circadian rhythms)
• Consecutive Waking Hours
• Night Sleep Duration
• Sleep Inertia
DETERMINANTS OF ALERTNESS AND PERFORMANCE
Wertz et al., JAMA 2006
Time Course of Deficits from Sleep Inertia
Fighters
All aircraft
Hours since 6 am wake time1 2 3 4 5 6 7
Aircraft Accident Data (Israeli Airforce)
Ribak et al., Aviat. Space Environ. Med., 1983
Sleep InertiaSleep Inertia
Chronic sleep restriction progressively degrades reaction time, particularly during circadian night. Cohen DA, et al. Science Translational Medicine 2010
Shift Work Coping Problems Personal Factors
Shift Work Coping Problems Personal Factors
• Age ≥50 years
• “Morning-type” person (“lark”)
• Heavy domestic workload
• Second job (“moonlighting”)
• History of…
– Sleep disorders
– Medical illness
Adapted from: Monk TH. Shift Work. In: Principles and Practice of Sleep Medicine. 3rd ed. 2000:600.
Degrees of Excessive SleepinessDegrees of Excessive Sleepiness
During times of restor when little attention
is required
During daily activities requiringmoderate attention
Marked impairment and severe sleepiness
during activities requiring
mild-to-moderate attention
Se
ve
rity
Falling asleep or nodding off…
Adapted from: International Classification of Sleep Disorders Diagnostic and Coding Manual. 1st ed. Westchester, IL: American Academy of Sleep Medicine; 2000:23.
• Riding in a car• Watching TV• Reading
• During conversation• Eating a meal• Driving• Walking
• Watching a movie• Attending a concert• In a meeting
Relative Risk for Injuries and AccidentsRelative Risk for Injuries and Accidents
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Rel
ativ
e R
isk
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Rel
ativ
e R
isk
Morning
Afternoon
Night 1 2 3 4
By Shift By Successive Nights
Folkard S, Tucker P. Occup Med. 2003;53:95-101.
Effects of 24-hour Shifts on Safety
0
0.2
0.4
0.6
0.8
1
1.2
Crashes per 1000 commutes home
OR: 2.3 (95% CI, 1.6-3.3)
Barger LK et al. NEJM 2005; 352:125-134
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Injuries per 1000 opportunities
Motor Vehicle Crashes Percutaneous Injuries
OR: 1.6 (95%CI, 1.5-1.8)
Ayas, et al. JAMA 2006; 296:1055-1062
Extended shifts
Non-extended shifts
100 Car StudyVirginia Tech and NHTSA100 Car Study
Virginia Tech and NHTSA
•Naturalistic study of 100 cars for one year
•82 crashes, 761 near-crashes
•Fatigue contributing cause in: 20% of all MVCs & 16% of all near-crashes
•Suggests could be as many as 8,000 fatigue-related fatal crashes in U.S. each year
http://www.vtti.vt.edu/PDF/100-Car_Fact-Sheet.pdf
0
5
10
15
20
25
30
35
40
Gastrointestinal Disorders in Night-Shift Workers Gastrointestinal Disorders in Night-Shift Workers
0
2
4
6
8
10
12
14
16
18
DayShift
RotatingShift
Prevalence of Ulcers in WorkersExperiencing Insomnia or Excessive Sleepiness
Prevalence of Ulcers in WorkersExperiencing Insomnia or Excessive Sleepiness
% o
f W
ork
ers
% o
f N
urs
es
Day Shift
RotatingShift
Functional Bowel DisordersFunctional Bowel Disorders
*P <0.05 vs no insomnia or ES
Drake CL, et al. Sleep. 2004;27:1453-62
†P = 0.04 vs day shift.
Zhen Lu W, et al. Eur J Gastroenterol Hepatol. 2006;18:623-627.
6.0
12.5
NightShift
15.4*
*†
38
20
Shift Work and the Risk for Coronary Heart Disease in 79,109 Nurses
Shift Work and the Risk for Coronary Heart Disease in 79,109 Nurses
*P <0.05 vs no shift work.
Kawachi I, et al. Circulation.1995;92:3178-3182.
0.0
0.5
1.0
1.5
2.0
2.5
Rel
ativ
e R
isk
(95%
CI)
No Shift Work
Any Shift Work
1.00
1.23
FatalCHD
NonfatalMI
1.00 1.00
1.41 1.38
TotalCHD
* *
Studies Demonstrating a Significant Risk for Cancer Among Shift Workers
Studies Demonstrating a Significant Risk for Cancer Among Shift Workers
Type of Cancer Odds Ratio 95% CI Reference
Breast cancer
Night shift ≥0.5 year
Night shift >6 years
1.5*
1.7*
1.3 – 1.7
1.3 – 1.71
“Graveyard shift” (any)
Shift work ≥5.7 hours/week
1.6*
2.3*
1.0 – 2.5
1.0 – 5.32
Rotating nights; ≥30 years 1.36* 1.04 – 1.78 3
Rotating shift work: >20 years 1.79* 1.06 – 3.01 4
Prostate cancer
Rotating shift work 3.0* 1.2 – 7.7 5
*P <0.05 vs comparator group.
1) Hansen J. Epidemiology. 2001;12:74-77; 2) Davis S, et al. J Natl Cancer Inst. 2001;93:1557-1562; 3) Schernhammer ES, et al. J Natl Cancer Inst. 2001;93:1563-1568. 4) Schernhammer ES, Epidemiology 2006;17:108-111; 5) Kubo T, et al. Am J Epidemiol. 2006;164:549-555.
Fatigue ManagementFatigue Management
Systemic Changes: Schedule Design and Other Workplace Interventions
Systemic Changes: Schedule Design and Other Workplace Interventions
• Eliminate shifts >12-16 hours
• Limit the number of consecutive night shifts
– The fewer, the better
– >4 12-hour night shifts associated with greatly increased risk of performance lapses1
• Schedule rotating workers to rotate “clockwise”
• Screen workers for sleep disorders
• Educate workers about the risks of driving and working while sleep deprived
Rotating shift work schedules that disrupt sleep are improved by applying circadian principles
Rotating shift work schedules that disrupt sleep are improved by applying circadian principles
Czeisler CA, Moore-Ede MC, Coleman RM. Science 1982; 217:460-463
• Intervention changed workers’ rotation from “phase advance” to “phase delay”, and increased time on rotation to 21 days
• Significant improvements in worker satisfaction and productivity (22%, p<0.001) after change
Philadelphia Police DepartmentPhiladelphia Police Department
Center for Design of Industrial Schedules. 1988. Boston, MA.
• Circadian-based scheduling intervention (change from phase advance to phase delay)
• At Baseline:−Over 50% of officers reported moderate to
severe problem with sleep quality−Over 70% admitted falling asleep on the job
during the night shift• Post-intervention:
−Four-fold reduction in poor quality sleep−29% decline in sleep episodes at work−40% decline in patrol car crashes−38% increase in family satisfaction
Effect of Implementing a Sleep and Circadian Science–Based Intervention Schedule on
Interns’ Serious Medical Errors
Effect of Implementing a Sleep and Circadian Science–Based Intervention Schedule on
Interns’ Serious Medical Errors
Lockley SW, et al. , Landrigan CP, et al. N Engl J Med. 2004;351:1829-1837; 1838-1848.
0
20
40
60
80
100
120
140
160
SeriousMedical Errors
- Total
SeriousMedication
Error
SeriousDiagnostic
Error
Traditional "q3" 24-30hour shifts
Intervention Schedule- <16 hour scheduledshifts
Bright Light and Sleep/ Darkness for Alleviating Maladaptation to Shift WorkBright Light and Sleep/ Darkness for Alleviating Maladaptation to Shift Work
• 54 subjects
• Simulated 4-day, 3-night shift work
• 38-hour constant routine (CR)
• Light during 8-hr “shift work”
– Bright (~2500 lux)
– Room (~150 lux)
• Sleep
– Fixed 8 hr; darkened room
– Free schedule
• Nighttime alertness
– P <0.01: bright light vs room light
– P <0.01: fixed sleep vs free sleep
Bright Free
Bright Fixed
Room Free
Room Fixed
Horowitz TS, et al. Am J Physiol Endocrinol Metab. 2001;281:384-391.
0
10
20
30
40
50
60
70
SubjectiveAlertness
Individual LevelIndividual Level
• Nonpharmacologic interventions– Work schedule changes– Lifestyle changes– Exercise
• Nonprescription interventions– Light– Melatonin– Caffeine (coffee, tea, colas, energy bars, caffeine tablets)– OTC sleep aids
• Prescription interventions– Sleep promoting medications– Wake promoting medications
Effect of Exogenous Melatonin on Sleep Efficiency in the Presence or Absence of Endogenous Melatonin
Effect of Exogenous Melatonin on Sleep Efficiency in the Presence or Absence of Endogenous Melatonin
• Endogenous melatonin levels are… – High at night
– Low during the daytime
• Exogenous melatonin…– Increases the duration of sleep
occurring out of phase with endogenous melatonin secretion
– Attenuates the wake-promoting drive from the circadian system
– Has little effect when taken at times when endogenous melatonin is present
75
80
85
90 Melatonin 0.3 mg
Placebo
Melatonin 5.0 mg
Low to AbsentEndogenous
Melatonin
ElevatedEndogenousMelatonin
**
Wyatt JK, et al. Sleep. 2006;29:609-618.
Mea
n S
leep
Eff
icie
ncy
(%
± S
EM
)
Phase Shift in Circadian Rhythms With Melatonin in a Simulated Night-Shift Study
Endogenous Dim-Light Melatonin Onset
Phase Shift in Circadian Rhythms With Melatonin in a Simulated Night-Shift Study
Endogenous Dim-Light Melatonin Onset
Placebo Melatonin0.5 mg
Melatonin3.0 mg
Sharkey KM, et al. Am J Physiol Regulatory Integrative Comp Physiol. 2002;282:454-63
P <0.05
P <0.001M
ean
Ph
ase
Sh
ift
(ho
urs
)
1.7
3.0
3.9
0
1
2
3
4
5
CaffeineCaffeine
Baseline Extended Wake Duration
0 8 16 24 4.8 28.6 42.9Hours
Wyatt JK, et al. Sleep. 2004;27:374-381.
PlaceboCaffeine
CognitionDSST (# correct)
Vigilance & ReactionPVT (slowest
10% [msec])
SleepinessKSS (units)
1510
50
-5
0
1000
2000
-10123
SLEEP
SLEEP
SLEEP
SLEEP
SLEEP
SLEEP
P <0.05
P <0.05
P <0.05
Treating Daytime InsomniaTreating Daytime Insomnia
• Sleep hygiene– Dark, cool, quiet bedroom– Avoidance of caffeine, tobacco, and alcohol– Consistent sleep & wake times– Regular exercise– Cognitive therapy
• Nonprescription interventions– Antihistamines
• Prescription interventions– Benzodiazepines– Nonbenzodiazepines– Sedating antidepressants
Shift Work Disorder (SWD): Diagnostic Criteria
Shift Work Disorder (SWD): Diagnostic Criteria
Adapted from: International Classification of Sleep Disorders Diagnostic and Coding Manual. 2nd ed. Westchester, IL: American Academy of Sleep Medicine; 2005.
(1) Insomnia or excessive sleepiness temporally associated with a recurring work schedule that overlaps the usual time for sleep;
(2) symptoms must be associated with the shift work schedule over the course of at least one month;
(3) circadian and sleep-time misalignment as demonstrated by sleep log or actigraphic monitoring for ≥ 7 days; and
(4) sleep disturbance not explained by another sleep disorder, medical or neurological disorder, mental disorder, medication use, or substance use disorder.
Modafinil for Excessive Sleepiness in Patients With SWDModafinil for Excessive Sleepiness in Patients With SWD
0
1
2
3
4
5
0
20
40
60
80
% o
f P
atie
nts
Im
pro
ved
Placebo Modafinil 200 mg
*P <0.001 vs placebo.†P = 0.002 for change from baseline vs change from baseline with placebo.
Czeisler CA, et al. N Engl J Med. 2005;353:476-486.
Min
ute
s
36
74
2.4
3.8
Clinician’s Global Impressionof Change (Improvement)
Clinician’s Global Impressionof Change (Improvement)
Sleep LatencyMSLT
Sleep LatencyMSLT
*†
Baseline Final VisitFinal Visit
Reducing the Effects of Sleepiness When Commuting
Reducing the Effects of Sleepiness When Commuting
• Shift workers have a greatly increased risk of suffering a motor vehicle crash on the drive home from work1,2
• Measures for the employer– Facilitate establishment of taxi services and/or company car pools
– Provide a place for workers to nap before driving home
• Measures for the employee– Minimize commuting; move closer to the work place or use public
transportation
– Avoid traveling at high speeds on highways
– If you feel sleepy when driving, pull over and nap; rolling down the window and turning up the radio will not work
1) Barger LK, et al. N Engl J Med. 2005;352:125-134;2) Gold DR, et al. Am J Public Health. 1992;82:1011-4.
SummarySummary
• A large segment of the U.S. population works shifts
• Shift workers are prone to circadian misalignment, acute sleep deprivation, chronic sleep deprivation, and sleep inertia
• These forces increase the risk of accidents, injuries, mistakes on the job, and motor vehicle crashes (either on the job or driving home)
• Systemic interventions to optimize work schedules have been shown to be effective across occupations
• At an individual level, optimizing sleep hygiene, melatonin, caffeine, and pharmaceuticals can be helpful