Sleep and Sleep-Wake rhythmicity: impact on (shift) work

dr. Gerard A. Kerkhof, prof. em.University of Amsterdam & MCH Sleep Center, The Hague

Seminar ‘Safety in Seafisheries’ – Oct 3, 2013

Edison’s prophesy: “Artificial light frees us from the night”

“Shift work”: work outside the hours 7 a.m. - 7 p.m.

Representative NL-survey (18-70 yr); N=2089

Unemployed (incl. school, retirement) N=701 34%

Employed N=1388 66%

- Regular day work N=1078 78%

- Shift work N=311 22%

Prevalence of Shift Work in other countries

Europe: 6.4% (Turkey) – 33.5% (Croatia), Average:17%

United States: 20%

Australia: 13%

Kerkhof GA (2013), in preparation.

A day (and night) in the life of 18-24 yr adolescents:

% mobile text traffic over 24 hours

Yesterday newspaper (Volkskrant):Day and night young people are busywith their mobile: ‘Socialbesitas’?

Carpe diem has become carpe noctem for me

(Kerkhof GA, in preparation, 2013)

Unemployed & Retired

Shift work

Other regular work hours

Regular day work

0 5 10 15 20 25 30 35 40 45

% Sleep disorder

Shift work increases the risk of a sleep disorder

Risks: Accident

s Illness

‘Fatigue’ is often synonymous with ‘Sleepiness’

(“Are you also so tired?”)

Crash Airbus, Tripoli May 12, 2010,

06:01a.m.

Accumulation of: Miscommunication (captain & co-pilot & Tower) Unexpected poor visibility (fog patches) No Instrument Landing System No evaluation of landing errors 2 wk earlier Fatigue (2nd night shift, early morning)

Conclusion: ‘Pilot error’ (i.e. Fatigue)

Risk analysis:‘Swiss cheese model’

(holes = risks)

Accident

Fail-Safe

Bhopal, India,12.03.1984, 1 a.m.

Chernobyl, Russia,04.26.1986, 1.30 a.m.

Exxon Valdez, Alaska03.24.1989, 1 a.m.

0 3 6 9 12

15

18

21

24

-25

-15

-5

5

15

Time of Day (h)

Avg

sco

re

Disasters during the night

Three Mile Island, U.S.A.,03.28.1979, 4 a.m.

(Mustard et al, Occup Environ Med, 2013)

1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

0

1

2

3

4

5

6

7

Time of Day (h)

Rate of work injury per 200,000 h worked

(Ontario, 2004 – 2008; N=707933)

Impaired motor coordination and accuracy

Other: Growth suppression Risk of Alzheimer’s disease

Health risks of shiftwork

Insuline resistance Obesity Diabetes type 2

Gastro-intestinal disease

“Metabolic syndrome”

Sleep disorder Fatigue (chronic) Cognitive disfunctioning: errors in perception, concentration, memory, decision making, etc. Emotional disregulation Irritability Anxiety

Disrupted immune system

Impaired motor coordination and precision

In addition: Breast cancer Growth suppression Alzheimer’s disease

Cardiovascular disease Increased cholesterol level Hypertension

BiologicalClock

Sleep

Shift work

Family

Circadian pacemaker

3rd ventrikel

Chiasma

Cross section of brainNerve impulses

Network of Clock genes

Suprachiasmatic nuclei

12 24 h00

The Biological Clock is tuned

to the day/night cycle

Michel Siffre, 1962 Sleep periods

Freerunning

Synchronized

10 12 14 16 18 20 22 24 2 4 6 8 10 u0

20

40

60

80

100

Metabolism Body temperature AlertnessPerformance Lymphocytes Growth hormoneMelatonin Cortisol

%

The Biological Clock conductsan orchestra of 24-h rhythms

Sleep

May 25th 2009: start Plymouth, UK Newport, USAappr. 3000 miles, 5 time zones

One sailor, one boat, one ocean

UK

USA

Plot of wrist activity (black) superimposed upon plot of daylight (yellow), from the start in Plymouth UK until the finish in Newport USA. Time axis: clock time in NL.

Start

Finish

Mean sleep duration/24h: 6.5 h, 2 hours less than baseline

46% sleep/8h dark (baseline: 73%)

Sleep bouts: mean 12’

Periodogram analysis: 24h amplitude equivalent peaks: 13h, 17h

Activity recording of solo sailor

08 08 0816 24 2416

1. Circadian process

2. Sleep process

Time of Day (h)

Sleep Sleep

(GA Kerkhof, 2013)

Two processes for Fatigue modeling

3. Sum

08 08 0816 24 2416

Circadian process

Sleep process

Time of Day (h)

Wake Sleep

(GA Kerkhof, 2013)

One night sleep deprivation increases the sleep process

Sum

(Kerkhof GA et al. 2003)

Long distance coach driving

Activity monitor

Sleep cabin

NL > Sp Spain Sp > NL Home0

2

4

6

8

Mean sleep duration (N=30)

h

15 21 03 09 15 21 03 09 15 21 03 090

0.25

0.5

0.75

1

Subj. sleepiness (N=30))

Time of Day (h)

Avg

. Sco

re

Ride Ride

(Folkard & Tucker, 2003)

Risk of accidents increases over successive nights

1 2 3 40.9

1

1.1

1.2

1.3

1.4

NachtDag

Successive days

Re

lativ

e r

isk

NightDay

BiologicalClock

Sleep

Shift work

Family

18 22 02 06 10 14 18

Time of Day (h)

↔ ↔

sleepworkNight shift

Early shift

Late shift

(Knauth & Rutenfranz, 1981)

Sleep duration for different shifts

Deep sleep

Hypnogram: sleep stages

REM-sleep

Electroencephalogram

Deep sleep

Growth hormone

Prolactin

Sleep: period of recovery and consolidation

REM-sleep

18 22 02 06 10 14 18

Wake1/REM234

Wake1/REM234

Time of Day (h)

Day sleep differs from Night sleep

Successive days of sleep restriction

4h

6h

8h

(Van Dongen et al, 2003)

TIB:

Daily averages of number of PVT lapses over two successive weeks of sleep restriction (N = 36)

Psychomotor Vigilance Test

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70

0

200 0

400 0

600 0

800 0

RESPONSE NUMBER

60 Hours Awake

36 Hours Awake

12 Hours Awake

84 Hours Awake

0

200 0

400 0

600 0

800 0

0

200 0

400 0

600 0

800 0

0

200 0

400 0

600 0

800 0

10 min Psychomotor Vigilance Test (PVT)

Doran SM, Van Dongen HPA, Dinges DF (2001). Sustained attention performance during sleep deprivation: Evidence of state instability. Archives of Italian Biology 139: 253-267.

With increasing sleep deficit performance becomes

more unstable and unpredictable

Meetmomenten Measurements

(Kerkhof GA & Hofman P, 2010)

0

2

4

6

8

10Lapses of attention (N=6)

#

0

2

4

6

8

10Day (M = 1.81)

#

1 3 5 7 9 11 13 15 17 19 21 23 25 27 290

2

4

6

8

10 Night (M = 2.03)

#

Variability of lapses at night

0 4 8 12 16 20 24 28 32 36 40

hours awake

1

2

3

4

5

Sta

nfo

rdS

lee

pin

ess

Sca

le

08 12 16 20 00 04 08 12 16 20 00time of day

0 4 8 12 16 20 24 28 32 36 40

hours awake

0

5

10

15

20

25

PV

Tla

pse

s

08 12 16 20 00 04 08 12 16 20 00time of day

Lapses of attention

n=8

n=7

Van Dongen HPA, Maislin G, Dinges DF (2004). Dealing with inter-individual differences in the temporal dynamics of fatigue and performance: Importance and techniques. Aviation, Space, and Environmental Medicine 75(3, Section II): A147-A154.

Individual differences in vulnerability to sleep loss Subjective sleepiness is unreliable indicator of impact

Subjective sleepiness

Empirical Best Linear Unbiased Predictors

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

0 1 2 3 4 5 6 7 8 9 10 11

subjects

rela

tiv

e p

erfo

rm

an

ce

Individual Differences in Vulnerability to Sleep Loss

in Active-Duty F-117A (Night Hawk) Fighter Pilotsleft 720 degrees turn

roll performance

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

-6 -1 4 9 14 19 24

time of day

N=10

fligh

t pat

h de

viati

on

left 720 degrees turnroll angle performance

pilots

rela

tive

perf

orm

ance

(Self-)selection mechanisms do not eliminate individual differences

in vulnerability to sleep loss

38-hour extended mission time

Van Dongen HPA, Caldwell JA Jr, Caldwell JL. Investigating systematicindividual differences in sleep-deprived performance on a high-fidelityflight simulator. Behavior Research Methods, 2006; 38(2): 333–343.

Recap 1. Fatigue/Sleepiness is a major risk factor and sum of a circadian rhythm with its maximum at night, and a sleep process that increases as a function of time awake

2. The vulnerability to sleep loss is an individual trait

3. Subjective sleepiness is an unreliable predictor of the risks of sleep loss

4. Sleep loss induces impaired and unpredictable performance

5. Shift work increases health risks

6. Consider preventive measures