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