ptt)

TABLE XI

EPI PRE COMPARISONS: 2-2-1 US. STEADY

woe ee ee eee | ---------~----------- +--+ -----
2-2-1 DAYS PRE I 2-2-1 EVENING PRE
Us. I us.

STEADY DAYS PRE I STEADY EVENING PRE
------- +--+ ee ]-----------------------------
48 I 1.56 I +26 1 40
1.81 I £90 I 53 I 165
1.05 I 51 I 299 I 96
+24 1 132 I 1.43 I 81
30 I 64 I 76 I 1.03
65 I .83 I .68 I 83
1.54 I 92 I 1.21 I 40
89 I 2.58 I .61 I 195

163 I 37 I 40 I
1.48 I 35 I 1.23 I
=50 I 1 61 1
196 I 1 2.44 I
+92 1 I 99 I
179 I I 1.26 I
95 I I 1.34 I
£28 I I 128 I
+26 I I 54 I
51 I I 1.03 I
30 I I 229 I
o-++- 2-2 eee --- |-------------- [------------~- [--------------
I I I
765 I 898 i .888 I 754
I I I
weeenn enn e anes [-------------- ]-------------- ]--------------
I
544 I 504
I

18


TABLE V

FCL COMPARISGN OF 2-2-1 WATCHES - POSTSHIFT

fl t 1 1 t '
1 1 ' 1 i '
1 H 1 1 1 1
1Q lem e2eocmos2om oN 1 ow 1 '
es ne ee nar 1 ee ee | 1
Se en ee ee) ‘ 1
1 1 a 1 1 om ot 1
1 1 1 1 . 1 1
1 1 1 l oN ot
cee ce re >
1 1 1 1 ' sd
root 1 1 ' '
12 4 1 1 ' 1
15 Leese anacanone , Oo tf 1 '
Zz 1 . : . ° 1 ee ee) ' t
a) LORRAN SAW EN A oom oo 1 1
'> 4 1 tO 1 ,
‘i ot ' : 7 4 1
1 1 1 L 1 1
[nA a nak eat at ne bt Re tet Re bet Red et nt et pt pt tet dA pt et ee ee ee ee
1 ' 1 t ‘ 1
1 Hi 1 ' 1 1
1 1 1 1 ‘ 1
1QO 1eee25 cD DO000 1 foo 4 1
Pe ee ns er i 1
PE thw tent amanm 1 ys ‘ 1
1 i a ) 1 !
1 1 1 1 . 1 1
i 1 i 1 tor 4
a ae ee ee DD ee
1 1 fi t 1 5
1 1 ' 1 1 '
' 1 ' 1 1
x 1PFee@ one eHNHeEM foo boom 1
Zou * ' ee (
a IND SRSnadans fo om 6 oF 1 1
f aad ( too 1 '
1 1 1 soot 1
t 1 1 1 '
‘ 1 1 ' fl
oo 1 1 ‘ i
Zo 1 1 ‘ 1
BS (emer ese eneoencane mh obo 1 '
zou oe ve m4 1 t
ii PXAKenKaSKSdaMYSN a 1 ow 1 1
> 3 gS 1 oN 1 t
m4 1 + 1 1
1 1 1 1 '
PO et Ren ee Re Rn eee Ot
' 1 8 1
1 1 1 7 4
‘ 1 1
BF Lem e2reennenannnonm 2 o 1 1
1 > * * * = ‘ 1
fan) [Nd aisacadaaddans oO on ' 1
i 1 tt dott Oo 1
' 1 7 ot 4
i 1 1 4

wi a

1>< . >

n =

a

12


p(t)

TABLE XU

1 PRE COMPARISONS: iS. STEADY
[aan een enn nn nnn nnn nnn nnn ne [~---------------- 2-6-8 ------
I 2-2-1 DAYS PRE I 2-2-1 EVENING PRE
I US. I us.
I STEADY DAYS PRE I STEADY EVENING PRE
[--- +--+ een nn ren nnn nn nnn [-----------------------------
1 4.58 I 13.46 I 3.07 if 5.19
I 9.64 I 7.2? I 8.90 I 5.92
I 5.51 I 3.03 I 11.64 I 9.01
I 6.01 I 3.03 I 15.76 I 3.87
I 3.71 I if.10 I 5.65 I 9.90
I 6.69 if 5.44 I 8.17 I 4.30
I 10.46 I 9.22 I 6.59 I 3.50
I 7.56 I 1B.72 I 5.84 1 7.3?
I 5.11 I 5.30 if 3.48 I
I 11.60 I 2.77 I 6.69 I
1 5.68 I 4.61 I 10.24 if
1 7.53 I 12.87 i 14.10 I
I 8.76 1 5.12 I 2.63 I
I 6.38 I I 6.16 I
I 6.97 I I 6,22 if
I 2.57 I I 2.81 I
I 2.44 I I I
I 3.90 I I I
q 2.27 t I I
]-eerr nnn nnn ]---------+++--- [-------------- [----2---------
I I I I
I 6.177 i 7.834 I 7.39? I 6.820
I I 1 I
I-------------- [-------------- [--+----------- [--2+e---n-nnn-
I I
if +262 I 703
I I

22


RESULTS
Fatigue Checklist:

The FCL data are presented in Tables II-VI. The review of the tables shows
there is significantly more subjective fatigue in the 2-2-1 group than in the
steady shift group when reporting for duty (preshift assessment). There
was no significantly different preshift level of subjective fatigue between
the steady day shift workers and the steady evening shift workers. There was
an insufficient number of steady midshift workers for comparison. As a group,
workers on the 2-2-1 rotation were significantly more fatigued by 8 hours of
work than were steady shift workers. In some cases, postshift fatigue was
classified as severe (score< 8) by 2-2-1 workers whereas no case of severe
fatigue was reported by steady shift workers. Subjective postshift fatigue reported
by workers on the 2-2-1 rotation was greater but not significantly so than
that reported by workers on the steady evening rotation.

With regard to fatigue, on the three watches of the 2-2-1 rotation, there
was a statistically significantly higher level of fatigue reported prior
to work on the day watch than on the evening watch (Table IV); such prework
fatigue differences as existed between the day and midwatches, and the evening
and midwatches were not statistically significant. In a few cases, particularly
prior to the 2-2-1 midwatch, prework fatigue was reported to be severe. There
was not a significant difference in fatigue levels after work on the 2-2-1 day
and evening watches. However, the midshift on the 2-2-1 caused significantly
more fatigue than did the day and evening watches with severe fatigue after
the midwatch in all but one case (Table V). When prework to postwork changes
in subjective fatigue were compared for the two shift patterns, no statistically
significant differences were noted (Table VI). The predominant change was in
the direction of increased fatigue reported in the postwork FCL; however, on
a few occasions the postwork FCL indicated a decrease in fatigue (Table VI).

Sleep:

The average amount of sleep obtained by subjects on the two work schedules
for each day of their workweek showed clearly that the most sleep .was. obtained
prior to the.first workday--8.3 h in both cases. On the. 2-2-1 rotation, ithe
amount of sleep prior to work declined almost linearly over the workweek to
5.4 h prior to the midwatch on the 5th day. ‘On the steady.shift pattern, the
amount of sleep declined from 8.3 h on day 1 to 6.8-6.9 h on days 2, 3, and 4
and to 6.2 h on day 5, The average amount of sleep obtained over the 5-day
workweek on the 2-2-1 schedule was 6.8 h and on the steady schedule, 7.0 h.
Both the day and evening watches on the steady schedule showed a decline in
the amount of sleep per night over the workweek.

Urine Biochemistry:

Statistical comparisons of ketegenic steroids (KGS) excretion levels during



TABLE «IT

2-2-1 DAYS POST
I US.
1 STEADY DAYS POST

I +63 1.59
3.01 OL
2.00 I +96
3.49 -08

p(t)

19



TABLE XVIII

2-2-1

NOREPI POST COMPARISONS:

eS Ss es

wenn nena en [oe ---- 2 n+ [2-2 -+- += [oo ee [ooo [--- =e

I

1 1 1
1 1 1
es er

Hy ont twwoan 1 oS Ft om 1

WOARKRKA TAA oS Pom bt oe 4

vote be te et ee t 7 od 7 ot

ANNA AN XO ee

a4 aN 1 1 1
! 1 oo

PO ne ee ne et ee
: 1 room
1 1 1 :
1 wm Ff wow 4

TROOANKRONWH 1 om Fo om 4

ARMTENR TOR oN fF 8 41

tots eet ewe 1 yd 7 OT

ANT TON RK oD PON po

= 1
' 4 1
jl ' t
1 1 1
oN bt on 4

in Os Stina i oS 1 wm 1

WSARKRA TASS ee

: Sree i yt :

ANNAN KN a oO om tf Nw 4

a an 1 1 1
1 1 Lo

RO ee ee ee
1 ' rom
1 ‘ 1 :
Pom fF om

ARDMORE HAO 1 o© + 8B 4

SRAKRR SOND ee

eo ee te ee yt :

TiaTaAMn Moan tom Fo om

aa Taaa Fo 4 1
H yl 1
1 1 1
' 1 1
oN Fo om 4

THODIANARROENSONHMAGA! KR 1 Bf

ATH OATTIRTeROAHSAM! BM 1 KR |

te ee NN en -

ANKRT HOUT TAN TN AMAR oO 1 ON 1

ae a 1 1 1
' 1 ot

en ee ee OO
1 1 i)
1 1 1 :
ee

AODAKRAKRDONKR®HAMSDwDAHS! SF | w I

SAKRADAKAKSOMNANR A SNe! NR | Af

cts eee te ee ee NO 2 4 °

TOHTNROADOMNRMOSARMHDORI N 1 aw 4

Naas Vaasa a ee '
1 D 1

x Ly oI

a oa

a es |

25



TABLE XIV

6.65 1.50
2.73 2.25
2.60 1.23
1.45 2.04
2.31 7.41
2.18 4.01

.324 1 134
I
I

o
o
BR

21

i

i.
i.
i.
2.
?.
4.



xd

S.E.

TABLE 1X

2-2-1
DAY MID I EVE
PRE PRE I PRE

891.35 1 1170.70 1 665.90
1625.40
897.35
693.60
809.40
1881.50
1536.10 1
252.90

891.35 1 665.90
1005.87 1 331.25
572.95 1 739.50
700.80 1 1625.40
561.83 | 898.90
407.00 642.35
462.10 897.35

16


TABLE I

I ITOTAL INUMBER INUMBER INUMBER INUMBER  [ NUMBER I NUMBER I
I SHIFT INUMBER = I1JQURNEY-IDEVELOP-ISUPER- ITELETYPE 1 WOMEN I MEN I
I ISUBJECTS IMEN IMENTALS IVISORS I0PERATORSI i I



TABLE XxXI

Revised Mean Values for SIH's - microgram/100 mg Creatinine

I
1 59 1.12
1

4 U.S, GOVERNMENT PRINTING OFFICE: 1985—461-816/20070

30


DISCUSSION

Objective differences, as judged by urine biochemistry, between workers
on the two shift patterns are minimal and insignificant statistically. However,
urinary excretion levels of adrenal steroids and catecholamines at MIA IFSS
are so high as to raise doubts about the validity of the analyses. As yet,

a technical reason for the high values has not been found. A diligent search
for experimental error has delayed this report beyond the reporting time
normally required for studies of this type and the search will continue as
long as personnel and facilities are available for this purpose or until the
validity of the high values is established. The statement above regarding
minimal differences between the two shift patterns is based on the assumption
that the cause(s) of the high SIH values, be it/they real or erroneous, affects
all analyses equally.

Extensive experience gained through studies in ATC facilities has imparted
some "feel" for the presence of high levels of stress. This "feel" is roughly
equivalent to clinical impression and is based on complaints .of fatigue out
of proportion to effort, expressed dissatisfactions, subclinical illness, sleep
problems, contentiousness, irritability, lecturing, speech making and focusing
of blame on management. None, or only insignificant amounts, of these negative
elements were: apparent to the investigators of MIA IFSS. Contrarily, the
employees who served as subjects were friendly, cooperative, interested,
hospitable, complimentary about management and seemed generally satisfied.

The reported amounts and quality of sleep were normal and in line with the
quantity of sleep reported for other industrial workers (1).

While there were no points of statistically significant difference in
SIH's between the two groups, there was a significantly greater excretion
of catecholamines on the day watch as compared to the evening watch on the
2-2-1 schedule. Though we have no data to support the statement it is
possible that there was a greater workload on the day shift that would
cause a proportionally greater excretion of catecholamines. Earlier work
in this laboratory has shown a direct and highly significant relationship
between catecholamine excretion and acute workload in tower controllers (5).

With regard to subjective fatigue there are several points of statistically
significant difference that are interpreted to be revealing of employee
attitudes toward their work. Generally, greater fatigue was reported both
preshift and postshift in connection with the 2-2-1 rotation than with the
steady shift. Preshift differences were significant for days and evenings;
there were too few steady midshift subjects for comparison.

Comparisons within the 2-2-1 shift groyp.showed that, day shift workers
reported significantly greater fatigue than did evening shift workers.
There was significantly greater fatigue reported in connection with the
‘midshift than with the day and evening shifts. Severe fatigue was reported
frequently after the midshift.


the off-duty and on-duty periods for the two work schedules showed no
significant differences. That is, prework as well as postwork stress levels

as indicated by adrenal steroid excretion were about the same for workers on

the two schedules (Tables VII & VIII). Comparison of KGS excretion in connection
with the day, evening, and midwatches of the 2-2-1 schedule likewise showed

no statistically significant differences (Tables IX-X).

There were likewise no statistically significant differences in
epinephrine excretion by subjects on the two work schedules (Tables XI-XII).
However, epinephrine excretion was significantly greater (p< 0.003) on the
day watch than on the evening watch of the 2-2-1 schedule (Tables XIII-XIV).

The profile of norepinephrine (NE) excretion was identical with that of
epinephrine; i.e., there were no points of statistically significant difference
between the two work schedules (Tables XV-XVI). However, as with epinephrine
there was significantly greater (p< 0.01) excretion of norepinephrine in
connection with day work than with evening work on the 2-2-1 schedule (Tables
XVII-XVIII).

In 1974 a stress index was formulated in this laboratory based on
excretion levels of the stress indicator hormones (SIH's) in urine (KGS, E,
and NE). This index facilitated comparison of stress at various ATC
facilities (5,7). Basically, the index consists of the product of resting
and working values of each SIH mathematically treated so as to provide a unitary
common denominator for each SIH. The SIH's are treated in this way so that
each will have equal importance in stress assessment; otherwise, the catechola-
mines' importance would be overwhelmed by the steroids' importance because of
the far greater amount of steroid material in urine compared to catecholamines.
The individual indices are designated cst (KGS), ce (E) and cne (NE). The
average of the three indices is designated Cs, the composite stress index.

When stress indices for all ATC facilities studied are listed (Table XIX),
MIA IFSS tops the list as the most stressful (Cs=2.60). Individual indices
for KGS and E are high at MIA IFSS although not the highest on the list. O'Hare
Air Traffic Control Tower (ATCT) and Houston ATCT (1970) have higher cst values;
Los Angeles and Oakland TRACON's (1974) have higher ce values. The high Cs
value at MIA IFSS is mainly due to the inordinately high excretion rate of NE
reflected in the cne of 5.85, about 5 to 10 times higher than other similar
facilities (Table XX).

It was thought that perhaps the high level of excretion of NE might be
a reflection of the age of the subjects. However, the correlation between
NE excretion level and age is not statistically significant (r=0.29, p>*0.30).
Some of the subjects were on medication for control of blood pressure; however,
there was no apparent significant correlation between medication usage and NE
excretion. Analytical reruns and audits of laboratory procedures have likewise
failed to reveal experimental error as the cause of the high values. Further,
urine collection procedures were identical to procedures used in other studies.
The same personnel performed these analyses by the same methods as in the
previous studies.


TABLE x

KGS PRE COMPARISONS: 2-2-1 PRE

2-2-1
1 DAY IT EVE 1
1 PRE oT PRE I
[--------- }--------- I
1 699.30 1 728.40 1
1 1427.20 1 1188.90 1
1 1030.75 1 1119.20 1
1 1924.90 1 2008.50 1
1 1792.98 1 1026.60 1
1 1110.90 1 1174.50 1
1 2362.80 1 740.30 1
1 809.15 1 957.50 I
1 990.90 I 1462.50 1
1 1460.80 1 486.00 1
1 1304.40 1 1550.05 1
1 896.55 1 1357.60 1
11159,95 1 444.90 I
I 898.07 1 857.70 1
1 1324.25 1 559.60 1
1 701.25 1 654.63 I
1 816.10 1 653.70 1
1 399.77 1 380.90 1
]--------- [--------- I
_t I I
X 1 1172.78 1 963.97 1
I I I
]--------- Jenn en enne I
I I I
S.E. 1 115.29 1 103.39 1
I I I
[--------- [-------+- I
I I
p(t) I .124 I
I I

[----~--------- = 22-22 nnn nnn nn nn nnn ee eee I

17



five" shift pattern was arbitrarily imposed in place of the established 2-2-1;
a sick-out ensued and labor-management tension persisted until the 2-2-1 was re-
stored. It is a serious mistake to think that the distribution of time off

is a matter of indifference to employees. Succinctly put, it can be said that,
given the opportunity, employees will choose an off duty time and accept
whatever work schedule is necessary to provide that choice.

This opinion is borne out, to some degree at least, by the findings of
this study. The MIA IFSS employees as a group possibly show the highest level of
acute workload stress of any ATC facility yet studied. The 2-2-1 workers
report severe fatigue in some cases. Yet these workers are apparently contented
and willing to accept such stressors. An observer cannot help but attribute
these workers' attitudes to participative management that gives employees
maximum control over their time consistent with operational imperatives.

NOTE: The reader is asked to review the Addendum on pages 29 and 30.



bal

ptt)

TABLE XVI

NOREPT POST COMPARISONS: 2-2-1 US. STEADY

I
I 2-2-1 DAYS POST I 2-2-1 EVENING POST I
I US. I us. I
1 STEADY DAYS POST I STEADY EVENING POST I
I---------~------------------- |-----------------+----------- I
t 4.09 I iii I 5.96 I
I 26.38 I 5.67 I 4.41 I
I i5.72 1 6.08 I 20.58 I
I 14.19 I 5.90 I 6.13 I
I 7.81 I 13.52 I 4.35 I
I 19.19 I 7.89 I 25.71 I
I 8.58 I 12.85 i 7.13 I
I 6.20 I 23.79 I 10.97 I
I 3.93 I 11,03 I I
I 47.0? I 3.60 I I
i 13.60 I I I
I 10.35 I I I
I 10.11 I I I
I 9.28 I I 1
I 17.50 i q I
I 5.16 I I I
I 6.09 1 I I
I 19.25 I I I
I 9.80 I I I
I----------~--- [-------------- [enew nnn nnn nn nn [enn e nner enna n- I
I I if I
I 12.710 I 10.144 I 10.655 1
I I I if
[+---+---+----- [-nn2---n----n- [-------------- [-------------- I
I I I
1 «462 if 142 I
I I I
l--------------------------------------------------- 2-2-5 -- I

23



Technical Report Documentation Page

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FAA-AM-85 ~ i
4. Title and Subtitle 5. Report Date

PHYSIOLOGICAL RESPONSES TO UNVARYING (STEADY) AND
2-2-1 SHIFTS: MIAMI INTERNATIONAL FLIGHT SERVICE 5. Performing Organization Code
STATION

8. Performing Organization Report No.

7. Author!s)
C. E. Melton

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute
P.O. Box 25082 TV. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name ond Address
Office of Aviation Medicine

Federal Aviation Administration
800 Independence Avenue, S.W. 14. Sponsoring Agency Code

Washington, D.C. 20591 He Z) (hu
(ie,

Work was performed under Task AM-C~83-PHY-135. Phe ppp Ces holes
Di dug pe Ale Milby

15. Supplementary Notes Sled

16. Abstract

Two types of shift rotation in the same air traffic facility were investigated
in order to determine the relative advantages and disadvantages of nonrotating
shift work (steady shift) and rotating shift work. The rotating shift work chosen
for comparison was a 2-2-1 pattern often preferred by air traffic controllers, and
which consists of a schedule of progressively earlier work periods throughout the
workweek, with 9 to 14 hours off duty between 8~hour work periods, and an extended
off-duty period of 80 hours between workweeks.

Objective differences, as judged by urine biochemistry, between workers on the
two shift patterns are minimal and insignificant statistically. Generally, however,
greater fatigue was reported in connection with the 2-2-1 rotation than with the
steady shift, both preshift and postshift. When prework to postwork changes in
subjective fatigue were compared for the two shift patterns, no statistically
significant differences were noted.

Within the 2-2-1 schedule, there was (i) significantly greater excretion of
catecholamines on the day watch as compared to the evening watch; and (ii) signifi-
cantly greater preshift fatigue reported on day shift than evening shift.

Despite the observed differences between and within the steady and rotating
shift patterns, employee participation in shift pattern choice may have contributed

greatly to worker contentment and willingness to accept the observed stressors,
A separate addendum clarifies specific biochemical data interpretation

difficulties encountered in this study.

17. Key Words 18. Distribution Statement

Shift Work, Air Traffic Controllers, Document is available to the public

Biochemistry, Fatigue, Employee through the National Technical

Participation Information Service, Springfield,
Virginia 22161

19. Security Classif. (of this report) 20. Security Classif. (of this page) Bi No. of Pages | 22, Price

Unclassified Unclassified 30

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



TABLE Til

FCL COMPARISON OF POSTSHIFT VALUES ON THE TWO SHIFT SCHEDULES

-----+1
I STEADY

I

]---------------------------------------

I
I

2-2-1 I STEADY I STEADY I
T EVENING I EVENING I

I
i

1 STEADY

I

2-2-1

BAYS

DAYS

aman ver eeae aera eevee aera arya

emntensot
x a x nor 3 as
“4

I

-+- [-------~- [---------]---------

rant tatoo
3 o os S 2 3 S ao
ot

11.4

I

eantencot
x 3 cio WR Sa4
4

ae

Doorn ToeMONTeMNN to

Nan a DOM onI KAAS
aa

10

Sant I nto ot

s o ao MOON at

a ae oe

Doan tomnoNntena to

Non a DORKS a ae
aoe

I I I

nS CS eS ES

I

61

.08

«02

I

I
--[--------------- 22+ [---- +--+ eo

10


TABLE If

FCL COMPARISON GF PRESHIFT VALUES ON THE TWO SHIFT SCHEDULES

ene

I

I STEADY
I EVENING T

STEADY

I

I STEADY

2-2-1

1
I

I STEADY

2-2-1

if

DAYS

1 EVENING I

DAYS

TNoMwotTONND
TANKRMOdI HS
aa aeteatetedt l

NOWWWVOTPMDFVDMONTATN
BAMNAROMKRAONRATHOKR
aoe

NWOowFenowvmMantHO TN

ARMDAROMKRHONKRT DOR
4 Bota at

a: oases ne nes Denne ns Ceo

I

I

I

I

10.3

1x

ween nee nn [enn nnn nee [ene n eens [oe eee = [oe nnnne [eee eee

155

I
I

- 0003 I
1

I

02
ns enna eee eee

pit) I

Note:

In all tables, Student's t test has been used to determine

statistical significance.



Uniformly (six exceptions), greater fatigue was reported after work
than before. However, prework to postwork differences were not significant for
the two shift schedules.

In the conduct of this study many opportunities were afforded to engage
in conversational interviews with the subjects. (rather u iform setqof
Sons was given. ; 2 ‘ik. pattern. : *. FR@asgns
n ‘e not related | LE. that most pebple
wl the steady shift did. sa in orde: Ind prédicyable
OEE ity period. Hep] : pattern said that the exténded
SfF"duty period at the. end of the workweek.was their. motivation for what
¥ehstcel Some people on both schedules said that they wanted to stay with
their accustomed teams.

ia

These personal and social factors illuminate certain human relations
considerations not usually addressed. The common practice is to assign
people to a schedule of work because of needs of the work place or employer.
Actually, it appears that salaried people who work for a living, as opposed
to creative workers such as artists who do not clearly separate vocation
and avocation, do so in order to enrich their off duty lives with the
compensation that they receive. Compensation always includes monetary
remuneration but may, and usually does, encompass more than that, including
such things as optimum time off duty when workers can enrich their lives
with the money received.

It has been pointed out that control over work is an important element
in job satisfaction. A fixed, unalterable, and ordained work schedule
represents an out-of-control element for most workers. Thus, efforts to
improve worker attitudes that are focused exclusively on environmental or
"hygiene" factors in the workplace may be misdirected. érke jose
) work schedules in order to get preferred. or exten £. Surveys
S“preferencd for work schedules, show that the 2 tion is prefetred
Ver the "straight five" shift. pattem. ‘This choice of compressed schedule
is based on a desire to get the 40-h workweek over with quickly (88 h) in

work
1 Work

A reversed 2-2-1 would, of course, allow only a 48h weekend which would
yield 32 h for waking activities, assuming two &h sleep periods. It is
probably significant that such an "easy" schedule is not in use at any

* 2 0 5 F

known ATC facility. Qtation patte provides 64 ;
i i 1 ft changes involved, but still

It is important to note that,*in general, the amount and quality of :
work to be done is the same for all shift rotation.patterns. All employees
work a basic 40-h week. The various shift rotation patterns only affect
the distribution of work throughout the 168 h, 7-d week, and thus affect
the distribution of time off. At one ATC facility that we studied, the "straight

6


S.E.

p(t)

TABLE XIII

EPI PRE COMPARISONS: 2-2-1

I I
2-2-1 1 2-2-1 — 2-2-1 [1 2-2-1 1 2-2-1 1 2-2-1
DAY I EVE I DAY I MIG I EVE I MID
PRE I PRE T PRE [ PRE T PRE I PRE
a atahaetaneen I---~-~---- ]--~------ |+---~----- I--------- [---------
243 I +26 I 48 I 51 I +26 I 51
i.81 I 53 I 1.05 I 1.05 I 299 T 1.05
1.05 I 199 I 124 I 46 I 1.43 I +46
+24 1 1.43 I 1.54 IT 2.89 I 1.2 T 2.89
30 I +76 if .63 I 82 I -40 I .82
65 I -68 I 1.48 1 2.35 I 1.23 1 2.35
1.54 Too..2. I 50 I .37 I .61 I 3?
89 I 261 I 296 I 50 1 2.44 I +50
63 I 40 I 192 I 1,53 I 199 I 1.53
1.48 1 1,23 I 295 I 94 I 1.34 I 294
50 I -61 I 30 I 69 I 229 I +69
96 1 2.44 T i I I
292 I 9 [ I I I
79 T 1.26 1 I I I
295 1 1.34 I I I I
+28 I -28 I I I I
-26 I 254 I I I I
FL I 1.03 I I I I
+30 I +29 I I I I
Staetatattetatl I--------- ]--------- [--------- [---=----- [---------
I I I I I
765 1 -888 1 +823 I 1,101 1 4.017 I 1.101
I I I I I
Saitetetatatatel [---+~-+--- |-------~-- [--+------- [--------- [--------
I I I I I
+106 I +123 41 .132 41 +250 1 .i9i. 1 +250
I I I I I
Steet l-~------- ]--------- [--------- [--------- [---------
I I
+375 I «099 I 783
I I

20


TABLE XIX

Comparison of Various ATC Facilities by Means of a Stress Index

|-------------------------- I--------- Teneennn-- 1
I Facility I Cc I Cc I
I I st I

I [--------- 1

I I I I
I Miami IFSS ('82) I 2.60 I 95 «dT
if I I I
I O'Hare ATCT ('68) 1 1.05 I 1.41 I
I I I I
I Opa Locka ATLT ('72) I .84 I +64 I
I I I I
T Atlanta ARTCC ('73) I .82 I 76 I
I I I 1
T Miami ARTCC (172) I .76 T  .6h 1
I I I I
I Los Angeles TRACON ('74) 1 175 T  .27 1
I 1 I I
I Houston ATCT ('70) I +74 I 1.27 I
I I I 1
I Qakland TRACON ('74) I «72 I .23 I
I I I I
I Houston ATCT ('71) I -68 I .89 I
I I I I
I Oakland TRACON ('72) I .60 1 .62 1
I I I I
I Los Angeles TRACON ('72) I .60 I .66 I
I I I I
I Fort Worth ARTCC ('73) I +34 I .22 I
1 I I I
I--------- I

* NOTE: The C for Miami IFSS was subsequently corrected as per the
s
Addendum (pages 29 and 30) to 1.46.

26


and (iv) 4 f
synchrony with

| being out o

oblems related to the ATCS's. working per.
fe's and/or children's activities.

Surprisingly, no published work has been found that compares stress
of rotating shifts with steady shifts in the same work setting. Therefore,
when we learned that the 2-2-1 and the steady shifts were both in use at the
Miami International Flight Service Station (MIA IFSS) we immediately set
procedures in motion to carry out a study at that facility aimed at comparing
physiological stress in ATCS's on the two work schedules. Further, employees
at the MIA IFSS could bid on work periods; many could consequently arrange
for regular off-duty activities.

The field phase of the study was carried out in late November and early
December 1982.

METHODS

Thirty-seven workers at the MIA IFSS volunteered to serve as subjects in
the study (Table I). The average age of the subjects was 42.6 years (range
24-62); the median age was 43 years.

Subjects were fully informed about the procedures and purposes of the
project; each signed an informed consent document prior to his/her participation.

Each subject collected two pooled urine specimens for each day of
participation representing his/her sleep period and work period. Acidified
specimens were frozen at the work site and remained frozen until they were
analyzed at the Civil Aeromedical Institute in Oklahoma City for 17-ketogenic
steroids (KGS), epinephrine (E), norepinephrine (NE) and creatinine (CR);
methods for these analyses have been previously published; values for these
urinary metabolites are expressed as weight/100 mg CR.

Thirty minutes prior to entering on duty, ATCS's reported to the temporary
laboratory where they turned in their rest period urine specimens, completed
preshift questionnaires regarding medication usage and physical complaints,
sleep reports, and subjective fatigue checklists (FCL). Subjects were then
fitted’ with chest electrodes for ambulatory electrocardiography (ECG), using
Avionics Electrocardiocorders, and were issued fresh urine collection vessels.
At the end of the work period, subjects completed a postshift questionnaire
and another FCL; the ECG electrodes were removed and a fresh vessel was
issued for collection of the next rest period specimens. Recorder malfunctions
not recognizable at the data collection site rendered most ECG tapes unusable;
only 23 valid ECG tape recordings were collected, hardly a sufficient number
for conclusive data. Heart rate values are, therefore, not reported.

. There were 16 subjects on the 2-2-1 schedule and 20 subjects on the steady
schedule completing all FCL's.


TABLE VI

FCL PRESHIFT-POSTSHIFT OIFFERENCES FOR THE TWO SCHEDULES

ee eS

1
I

1

I STEADY

I STEADY

STEADY

1 STEADY [ 2-2-1 I
I

2-2-1

T EVENING I

DAYS
=] -----2---]---------1

I EVENING I

I

DAYS

1
t
t
1
1
1
1
‘
1
i
t
'
'
'
t
1
1
1
1

I

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amAtsNaaams
1

I

AMD DBOADNNON

Head tAnw os
1

I

totrrTeNnwya oo

SeASNAaANS
t

I
I
I
I
1
I

VWTONTONN OT TOMO oT

Aad SdAtH I SAISON
n

I

ND DooDannon

ana at NAM oS
'

I

en ee Se ee

MIONTONNET Tod wos
NOSSHAT MA SOINM DON
i

I I I
1.78 | 2.14 1 2.04 I 2.14
I I

I
if
I

1 2.04
I
Joanne cen es [ene e cen n [oe nnn e ene [enn none [on ee nn ne Pee nen

I

1.78

I +92
1

65

I
I

73
[onan nena nnn nnn [one nnn nee nn nnn [ence ec een eel

I

p(t) I

* NEGATIVE VALUE MEANS THAT THE POSTSHIFT SCORE WAS GREATER THAN

THE PRESHIFT VALUE.

13



TABLE Vit

OMPARISONS: 2-2-1 VS. STEADY POST

5
wo
oO
a
a
o

pty

15



PHYSIOLOGICAL RESPONSES TO UNVARYING (STEADY) AND 2-2-1
SHIFTS: MIAMI INTERNATIONAL FLIGHT SERVICE STATION

INTRODUCTION

Previous work in this laboratory has shown that the 2-2-1 shift rotation
pattern in common use in air traffic facilities was less stressful than was
the "straight five" rotation pattern (4,6). The 2-2-1 consists of a schedule
of progressively earlier work periods throughout the workweek with 9 to 14
hours off duty (quick turnarounds) between 8-hour work episodes. The "straight
five" shift rotation schedule calls for weekly changes of work hours; on
this schedule an air traffic control specialist (ATCS) works 5 straight days
on the same watch and has 16 hours off duty between 8-hour work episodes.

The ATCS's generally prefer the 2-2-1 rotation because of the extended
off-duty period (80 hours) between workweeks. Management's attitude toward
the 2-2-1 is best described as reluctant tolerance, believing that the quick
turnarounds do not allow time for adequate rest between watches. However,
there is demonstrably less physiological stress associated with the 2-2-1 fhan
there is with the "straight five" schedule because the ATCS preference increases
job satisfaction and there is less circadian disruption since ATCS's effectively
work days and sleep at night except for the lone midwatch on the last day of
the workweek.

The earlier research réferenced above points out that five consecutive
midwatches on the "straight five" rotation is the most stressful event related
to ATC rotating shift work; 5 days is not long enough for circadian re-entrainment
to occur and thus allows accumulation of fatigue associated with inadequate daytime
sleep.

It has been argued by Czeisler et al. (2) that the direction of shift
change is as important as is the pattern of rotation. This contention is based
on the observation that the diurnal wake/sleep cycle (biological day) is longer
than the 24-h solar day in contrived experimental environments devoid of time
cues. Rotating schedules that involve progressively earlier watches, as does
the classic 2-2-1 pattern, are called "advancing" schedules; those that involve
progressively later watches are called "delayed" schedules. Delayed schedules
work in the same direction as the biological day and, therefore, are apparently
less stressful than are advancing schedules. For the same reason, east-to-west
flight (delayed schedule) across several time zones is less disruptive piologically
than is west-to-east flight (advancing schedule).

Nonrotating shift work (steady shift) is an obvious remedy to circadian disrup-
tion associated with rotating shift work. However, in air traffic control (ATC) work,
several objections to steady shifts, all related to the midwatch, have been raised:
(4) traffic is characteristically light on the midwatch, thus causing deterioration
of proficiency in handling heavier daytime workload should the ATCS be called on to
do such work; (ii) difficulties in making weekend and vacation adjustments to daytime



TABLE XUII

ut
oe
a
rm
bd
ier
a
Zz

I
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2-2-1

2-2-1 2-2

2-2-1

I
I

I 2-2-1

I

2-2-1
DAY

MIo
PRE

EVE
PRE

MID
| nS nS nS Enns OEE EEE

I

DAY

EVE

I

3.67

11.64

4.79
G12

1 25.13

-
is

8.90

I 11.64
1 15.76

9.64 I

5.51

I
I

1
1

6.01
10.

I
I

6.59

I

01

ma

7
a.

m

I
I

1 12.87
I 10.24

3

4.26

2.73

1 23.37
7

I

ms
poms

59
5.84

oo

ONT

won
=

i 2.81

215

4.61

68
7.53
8.76

I
I

12
I 10.24

[--------- [------- 2+ [oe 2-2-2 == [eee oe = [oon [eee e ene e el

I
if
I

I

I
I
I

I
I
I

1
I

I
I
I

I
1
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%

1 10.017

1

7.776

.017

7.390 6.751 10

6.180

Jenene ee [oon ene [enn ee [ooo nn nae [enon een ee [eee

I
I
I

if
1

I
I
I

I
1
I

1.448 2.897

2.897

1
I

.898

+895

I
I

+614

S.E.

I

I

[oonne ee e+ [---+ 2-22 - [o-oo ee = [eee -- +22 - eee e Penne eee --

I

p(t) I

[

I

I

-507

«183

. 180

'
1
1
t
‘
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1
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t
1
'
'
t
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1

24




Addendum

Since completion of the foregoing report, further laboratory work has
pinpointed the cause of the perplexingly high values for the urinary stress
indicator hormones (SIH's).

When the urine specimens were received at the Civil Aeromedical Institute
from the data collection site they were divided into two parts; one was acidified
for catecholamine analysis and the other was used "as is" for adrenal steroid
analysis. The Hormonal values were then made relative to 100 mg creatinine.

It is now believed that, by human error, samples for creatinine analysis were
taken from the nonacidified moiety, resulting in low creatinine values. Because
the weight of creatinine forms the denominator of the creatinine-based ratio,
calculated SIH's were inordinately high. The fact that all SIH values were high
impelled us to look first at the creatinine analysis, but the samples for the
reruns were again taken from the urine previously set aside for creatinine
analysis, thus giving the same result as the first run. It was only when we
started from "square one" that we realized what had happened.

Because the error is a relatively constant one, we do not believe that
conclusions regarding differences in the two shift patterns are compromised.
The computed level of stress is changed, however, to about half the value
reported. The Miami International Flight Service Station (MIA IFSS), though,
still retains its number one position on the stress index list, surpassing even
O'Hare Tower during the high-stress time of the 1968 ATC slowdown (IFSS Cs= 1.46,
ORD Cs= 1.05). The MIA IFSS is high on the stress index list solely because of
the inordinately high NE values. The reason for this high level of excretion
of the sympathetic nerve transmitter in the MIA IFSS population is still unknown.
The indexes for adrenal steroids (Cst) and for epinephrine (Ce) are nominal.
Physical exercise is known to increase NE output*; however, the subjects at
MIA IFSS as a group were not heavily into exercise, though some individuals
worked out regularly. Work in the facility did not seem to be mainly physical;
rather, it appeared to be a relatively sedentary occupation.

The general conclusion, based on these new data (page 30), would be
that MIA IFSS workers do not show a high level of chronic stress as indicated
by adrenal steroid excretion nor do they show a response to a heavy acute workload
in their urinary excretion of epinephrine.

The FCL data, of course, are not affected by this biochemical reappraisal.

* Howley, E. T. The Effect of Different Intensities of Exercise on the Excretion
of Epinephrine and Norepinephrine. MED. SCI. SPORTS, 8:219-222, 1976.

Dimsdale, J. E. and J. Moss. Plasma Catecholamines in Stress and Exercise.
J. AM. MED. ASSOC., 243:340-342, 1980.

Dimsdale, J. E., H. Hartley, T. Guiney, J. Ruskin, and D. Greenblatt. Postexercise
Peril; Plasma Catecholamines and Exercise. J. AM. MED. ASSOC., 251:630-632, 1984.

29



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14