TABLE IX

Comparison of Hours of Sleep Prior to Work

_————
Weekly Average
ee Shift Work Day (Derived from all
—— Rotation participating
Pattern 1 2 3 4 5 subjects)
Mid 7:04 6:58 6:56 7:11 7:10 6:58
5-day 4 | 1:03 0:09 0:57 1:11 4:40 0:53
(days)
p® fs 0.05 N.S. < 0.05 < 0.05 < 0.01 s 0.01
2.61
2.72
8:07 6:49 5:59 6:00 2:30 6:05
3.39 2-2-1 A | 2:08 1:15 0:35 O:11 3:50 0:06
ped N.S. N.S. N.S. N.S. < 0.01 N.S.
2.83 5-day 5:59 , 5:34 5:24 5:49 6:20 5:59
(mid)
3 44,
B.28 *Significance level of difference between values on day shifts and 2-2-1 rotation
wkSignificance level of difference between values on mid shifts and 2-2-1 rotation
B33 Sleep Patterns lers on the 5-day pattern slept an average of 57
sa inutes more than those on the 2-2-1, prior to
Table IX shows, day by day, for the 12 indi. 9 TMTMTM' .?
ft. 24, viduals who participated in both studies, the day 4 the group on the 5-day rotation slept 1
hours of sleep prior to work. Thé controllers on hour and 11 minutes longer, and prior to day 5
the S-day rotation slept significantly longer at the controllers on the 5-day rotation slept 4
night prior to day shifts than they did in the hours and 40 minutes longer. On a whole week
faction va ne y basis, when the controllers were doing day work
day prior to mid shifts. These same controllers ” . ing day
feelings . panes . on the 5-day rotation, they slept an average of
on the 2-2-1 rotation slept significantly less prior ih d 36 minutes } ight th:
‘or day to work than they did prior to day work on the our an minutes Tonger per nig an
wes be- 5-day rotation; however, the one mid shift in- they did a year later on the 2-2-1 rotation. How.
‘or the cluded in the 2-2-1 schedule substantially low- ever, when the single mid shift is not included
ratings the average amount of sleep because most in the comparison, on the 2-2-1 rotation they
yy shift trollers only took a short nap prior to that sle pt an average of 18 minutes more than th ey
stati single mid shift, © did prior to the first 4 days of the 5-day rotation,
on * . . When a week of work on the 2-2-1 rotation is
Every day on the 2-2-1 schedule is a quick compared with a week of mid shifts, it develops
tween turnaround day. The amount of sleep taken that, on the 2-2-1, the group slept an average of
‘AT or Prior to day 2 is not significantly different for 1 hour and 2 minutes more per night than they

the two rotation patterns; on day 3 the control-

i

did prior to 5 straight mid shifts.


[MON | TUE | WED | THU

. FRt | SAT | SUN | MO

i: Wi: il all

rebrpttpprtiprtirtir tis
gses33383388323833338 8
eseesee82eeseegeene 258 2

| Tue | wed | THU | FRI_| SAT | SUN

2-2-1 rotation

Straight 5-day rotation — day shift back on to day shift

Straight 5-day rotation — day shift back on to mid- shift

8 hour work period

MON
A
B
C_ Straight 5-day rotation — day shift back on to evening shift
D

Hours off between work periods — average of 12 hours on the
2-2-1 rotation; 16 hours on straight 5-day rotation

| Hours off between work weeks (off-duty days)

Ficure 1. Graphic representation of a week on the 2-2-1 and 5-day rotations: The weeks shown begin on Mon-
day; however, a controller's work week may start on any day and his weekend will necessarily be days other

than Saturday and Sunday.

men No. 1), during the first 4 hours (specimen
No, 2) and the last 4 hours (specimen No, 3) of
each shift. Blood specimens were taken from
each subject when he began his work week and
again at the end of his work week. Urine was
angpyzed for epinephrine, norepinephrine, 17-
ketogenic steroids, gen, potassium, and creati-
nine. “Blogd plasma was analyzed for total
phospholipid and phosphatidyl glycerol.

Each subject completed a series of question-
naires and psychological tests before and after
each shift under consideration. The following

techniques were used to assess mood, anxiety, and
attitude:
Br it Anxiety Inventory (STAI):
1S onnaire, developed by Spielberger,
Gorsuch, and Lushene,!® consists of two scales
ewhich ask the respondent to respond to items
concerning his éitéist' (A-trait) and current
(Hislate) anxiety levels. Each scale is comprised
of 20 items which the respondent rates on a four-
point scale. (Ae ical item would be “I feel
térige,” which w be rated from “almost al-
ways” to “almost never” for A-trait, ‘and from

per
tio:
ind
ject
dif

zk. |
El.

Day


will be
on the

a

i

»

REFERENCES

. Hale, H. B., E. W. Williams, B. N. Smith, and C. E.

Melton, Jr.: Excretion Patterns of Air Traffic Con-
trollers. AEROSPACE MED. 42(2) :127-138, 1971.

. Malmstrom, E, J.: Composite Mood Adjective Check

List. Unpublished manuscript, University of Call-
fornia, Los Angeles, 1968.

Melton, C. E., Jr., J. M. McKenzie, B. D. Polis, G. E.
Funkhouser, and P. F. Iampietro: Physiological
Responses in Air Traffic Control Personnel: O'Hare
Tower. FAA Office of Aviation Medicine Report
No, AM-71-2, 1971.

Melton, C. E., Jr., J. M. McKenzie, B. D. Polis, M.
Hoffmann, and J. T. Saldivar, Jr.: Physiological
Responses In Air Traffic Control Personnel: Houston
Intercontinental Tower. FAA Office of Aviation
Medicine Report, submitted for publication.

Polis, B. D., E. Polis, J. deCanl, H. P. Schwarz, and
L. Dreisback: Effect of Physical and Psychic Stress
on Phosphatidyl Glycerol and Related Phospholipids.
NADC-MR-6805, 1968.

6. Smith, R. C.: Assessment of a “Stress” Response-
Set in the Composite Mood Adjective Check List.
FAA Office of Aviation Medicine Report No. AM—
71-21, 1971.

Smith, R. C.: Job Attitudes of Air Traffic Control-
lers: A Comparison of Three Aw Traffic Control
Specialties. FAA Office of Aviation Medicine Report
No, AM-73-2, 1973,

8. Smith, R. C., B. B. Cobb, and W. E. Collins: Atti-
tudes and Motivational Factors in Terminal Area Air
Traffic Control Work. AEROSPACE MED. 43:1-5,
1972.

9. Smith, R. C., C. E. Melton, and J. M. McKenzie:
Affect Adjective Check List Assessment of Mood
Variations in Air Traffic Controllers, AEROSPACE
MED. 42 :1060-1064, 1971.

a

10. Spielberger, C. D., R. L, Gorsuch, and R. E, Lushene:
Manual for the State-Trait Anziety Inventory, Palo
Alto, Consulting Psychologists Press, 1970.



8.d.)

s.d.)

s.d.)

:

TABLE VI

Mean A-State and A-Trait Raw Scores for Air Traffic Controllers

Under Two Shift Rotation Schedules

Watch Time Rotation Schedule

5=day 2-2-1

A-Trait
one oone 30.0 29.3

A-State
Day Pre 29.4 30.6
Post 35.2 34.9
Evening Pre - 31.5
Post cone 33.9
Mid Pre 31.3 32.1
Post 35.8 36.2

both groups, the mean index for day shifts was
higher than mid shifts (p<.01 for both compari-
sons) ; however, the mean index for the day shift
was higher under the 5-day than the 2-2-1 sched-
ule (p<.01). There was no difference between
the schedules on the index for mid shifts, Within
the 2-2-1 schedule, there was a significant inter-
action (p<.01) between types of shifts and pre-
shift and postshift mood assessment. It was
found that, before work, the mean overall index
was higher for evening shifts than for day shifts
or gnid shifts (p<.01) for each comparison).
After work, the megn overall indices for evening
and day shifts were equal and lower than the
indices before work. The index for the mid
shifts was significantly lower than for both the
day and evening shifts (p<.01 for both com-
parisons).

There were no significant effects for seven spe-
cific mood factors, Aggression, Anaiety, Anaious,
Depression, Distrust, Dizzy, and Nonchalance.

There were five factors on which differences
between the two shift schedules were noted.
Mean Concentration and Social Affection scores
were higher under the 5-day schedule than the
2-2-1 schedule (p<.05 for both comparisons).
It was also found that prior to day shifts, the
mean Vigor and Surgency scores were higher,
and mean Fatigue scores lower, for the 5-day
than for 2-2-1 rotation schedules (p<.05 or bet-
ter for each comparison). This trend continued
to postday shift assessments only for the Vigor
factor. Furthermore, it was found that the pre-
shift Végor scores on both schedules were higher
for day than mid shifts, but after shifts this was
true only for the 5-day schedule (»<.05 or better



TABLE UT
Comparison of Heart Rates During Mid Shite

Work on S-day and 2-2-1 Rotations

Average Heart Rate

Saday oI
Work Position Rotation Rotations pete
Approach control radar n a £0.02
Departure control radar 15 a ”
Coordinator radar 82 86 ”
Supervisor radar n 8 ”
Local control cab % 15 o
Ground control cab 9 % ”
Clearance delivery 6 date 9 84 NS.

** pata not sufficient for statistical teat

‘fet Wilcoxon matched pairs signed rank test

of E occurred during nocturnal sleep by the
group on the 2-2-1 rotation; however, E excre-
tion over an entire week of day work was slightly,
but insignificantly, higher than E excretion over
a week on the 2-2-1 rotation.

When the mid shifts were similarly compared,
the excretion of E. was significantly elevated in
the 2-2-1 group, except during day sleep when
the two groups’ E excretion was equal.

2. Norepinephrine (NE). NE excretion was
significantly greater during day work on the
5-day rotation than on the 2-2-1 rotation. There
was no significant difference in NE excretion
during nocturnal sleep on the two rotation pat-
terns. The entire week of day work caused a
significantly higher excretion of NE than did the
2-2-1 rotation.

There were no significant differences in NE
excretion by controllers on the mid shifts of the
two rotation patterns. Likewise, NE excretion
did not differ significantly during day sleep on
the two rotation patterns,

3. 17-Ketogenic steroids (KGS). KGS excre-
tion was significantly higher during the first half
of the mid shift on the 2-2-1 rotation than it
was during the comparable period on the 5-day
rotation. That trend was reversed, however,
dyting day sleep when KGS excretion was sig-
nificantly elevated. in the 5-day group. When
the KGS data were normalized as percent of the
baseline (night sleep specimen D-3), adrenocorti-
cal responsiveness was seen to significantly
higher _i i f
of the mid shift and for the whole week than it

work was characterized by significantly elevated
KGS excretion by the 5-day group, The differ-
ence between the groups was not seen, however,
during nocturnal sleep.

When_a_week of day
work on_the 5: i d_to

day/evening work on the 2-2-} (D-4 specimen),
i yas spparent that the 5-day rotation was sig.
nificantly more stressful than was the 2-2-1 ro-
tation. Adrenocortical responsiveness (% base-
line) was not significantly different in the two
groups.

4. Sodium (Na) and Potassium (K). Na ex-
cretion and K retention were characteristic of
the 2-2-1 rotation on both the day and mid
shifts, with the exception of Na excretion on the
first half of the day shift. The two rotation
patterns could not be distinguished on the basis

of the Na/K ratio, however, for either day shift
or mid shift.

5. Phospholipids. Table V shows that there
are no points of statistically significant difference
between the two work schedules as far as total
plasma phospholipids are concerned. However,
the two shift rotation patterns can be differen-
tiated significantly on the basis of phosphatidyl
glycerol levels in the controllers’ plasma speci-
mens, with the higher value occurring in connec-
tion with both the day shift and mid shift of the
5-day rotation, When the change in phospholipid
levels over the work weeks (postwork minus
prework levels) on the two rotation patterns are
compared, there are no points of significant dif-
ference in either total phospholipid or phos-
phatidyl glycerol levels.

Psychological Measures

A. STAI. The findings for the two scales of
the STAI are summarized in Table VI. There
were no significant differences between the anx-
iety levels of the two controller groups as a func-
tion of shift rotation schedule.

Controllers under both shift rotation schedules
had significantly higher mean A-state than A-
trait scores (p<.05) for both comparisons). In
addition, the A-state level was significantly
higher after work than it had been before shifts
(p<.05 or less for each comparison). There
also appeared to be a slight tendency for A-state
levels to be higher in association with mid shifts
than other shifts; however, the differences were
not statistically significant.


Mon-
other

and

AI):
rger,
scales
items
yurrent

four-

it al-

"to “not at all:-for-Arstate. The
A-State Scale was administered to each subject
before and after each shift under consideration;
the A-Trait Scale was only administered before
the first shift of the work week.

= posite Mood Adjective Checklist
ae The CMACL, as developed by
Malmstrom,? was used to assess affective states
before and after selected shifts. This list con-
asiets..of 20 adjectives (e.g., angry, sleepy, happy)
seated by the subject on a nine-point scale fram
enof, at all” to “definitely," descriptive of his
current feelings. The CMACL was completed
before and after each shift on the 2-2-1 schedule,
and before and after the day and mid shift se-
quences on the 5-day schedule.

igg Attitude ond Shift Experience, Question-
ee each shift the subjects completed
A. questionnaire to indicate their attitudes toward
working the upcoming shift. (eg., How much
are you looking forward to working today?
‘How do you feel today?) on five-point rating
seales. For the specific questions refer to Ap-
pendix 1. After the shift a corresponding ques-
tionnaire was completed and, in addition to
indicating their attitudes and feelings, the sub-
jects were asked to rate the shift in terms of
difficulty and satisfaction.

TABLE I

Comparison of Heart Rates at
Different Work Positions
S-day va 2-2-1 Rotations

Average Heart, Rate
2-2-1

3-day
Work Position Rotation Rotation pete

Midsbite ,
Radar B a < 0,01
cob 1 co < 0.02
Supervisor 16 80 “
Prevork 1 a vs.
ALL positions 70 a + 0.01

Day vork
Radar on a ws.
off a 83 Ns.
Supervivor Pad a ”
Prevork a a3 NS.
ALL postttons a at ws.

+ Date insufficient for statistical test

‘th WElcoxon matched signed rank test

In addition to the various physiological, bio-
chemical and psychological measures, each par-
ticipant was asked to report the number of hours
of sleep obtained prior to reporting for work.

TABLE 11
Comparisons of Heart Rates During Day Work
fon Seday and 2-2-1 Rotations

Average Heart Rate

sohay
Work Position Rotation Rotation pie
Approach control radar a a us
Departure control radar 80 86 Ns.
Ground control 2 86 ”
Local control 86 66 ”
Clearance delivery & data 80 a ”
Coordinator a 3 N.S.
Supervisor radar 8s %0 ”

w* Data not suffictent to make a statistical test

we Wilcoxon matched pairs signed cank test

III. Results,
Physiological-Biochemical Measures

A. Heart rate. Table I shows a comparison
between various work positions during day/
evening work and mid shift work on the two
shift rotation patterns, Statistically significant
differences occur on the mid shift with the aver-
age heart rate being hi, ! jon.
Table IX shows, where data are sufficient for
statistical test, that there are no significant dif-
ferences during day work between heart rates on
the two shift rotation patterns for the various
work positions, Table II] shows only one point
of statistically significant difference between mid
shift positions on the two rotations: approach
control radar. Most of the mid shift data in
Table III are insufficient for statistical: compari-
son because of the fact that only one controller
was in the cab and one in the radar room. When
the different positions are considered separately,
data for each of them become scanty. Table I
shows data combined for the various positions.

Within the group on the 2-2-1 rotation there
are no points of statistically significant differ-
ence between work positions.

B. Urine Chemistry (Table IV).

1. Epinephrine (E). There was no significant
difference in E excretion by the two groups dur-
ing day work. A significantly elevated excretion


Appendix I
Form I

1, How much are you looking forward to working today?

very much quite a bit some not much not at all

2. How enthusiastic do you feel about doing ATC work today?

very high high some little not at all

3. In general, how do you feel today?

excellent good o.k. poor bad

4. How tense do you now feel?

very tense moderately tense slightly tense no tension completely relaxed

Form II

1. How do you generally feel now, after the end of a day's ATC work?

excellent good o,k, poor chad
see ~

2. How tense do you feel now? a

very tense moderately tense slightly tense no tension completely relaxed

_

3. How do you feel about today's shift?

very good good o.k. bad very bad .
r @
4, How satisfied were you with today's shift?

Ig lal J

very satisfied satisfied neither satisfied dissatisfied very
nor dissatisfied .. — dissatisfied

5. How difficult was today's shift? Be

very difficult difficult neither difficult ‘easy very easy
v nor easy



TABLE V

Plasma Phospholipids
5-day vs 2-2-1 Rotation

Total Lipid Phosphorus

Phosphatidyl Glycerol

Prework 5-day 2406 + 250.19 (s.d.) 34.23 + 4.16 (s.d.)
2-2-1 2211 + 186.43 27.48 + 3.62
p* N.S. p < 90.01
Postwork 5-day 2242 + 226,70 (s.d.) 35.16 + 5.44 (s.d.)
(day shift)
2-2-1 2222 + 181.60 28.42 + 3.49
P N.S. p 50.01
Postwork 5-day 2392 + 216.44 (s8.d.) 33.19 + 5.35 (s.d.)
(mid shift)
2-2-1 2227 + 165.88 29.07 + 3.70 (8.d.)
P N.S. ps 0.01
Prework 5-day 14.40 + 51.82 1.47 + 3.50
Postwork (day shift)
differences
2-2-1 26.80 + 41.60 0.80 + 5.37
p N.S. N.S.
Pre work 5-day -13.92%% + 66.46 -1.03 + 4.34
Postwork
differences 2-2-1 . 16.00 + 46.63 1.59 + 5.30
P N.S. N.S.

* Paired t test .
*k Prework values higher than postwork

B. CMACL. The CMACL data were scored
for the 15 mood factors developed by Malmstrom?
anf for an overall index proposed by Smith.**
The findings for the controllers under the 5-day
shift rotation schedule are discussed at length in
a previous publication.” ‘The results presented
within this section will be concerned primarily
with the comparisons between the 5-day and
2-2-1 shift schedules,

values.

The mean overall affect index of 6.94 (range
of possible values was one to nine) for control-
lers under the 5-day schedule did not differ sig-
nificantly from the mean of 6.88 for controllers
on the 2-2-1 schedule (the higher the index, the
more positive the affect). In both groups there
was a significant decline (Table VII) in the
overall index from preshift to postshift assess-
ments (p<.01 for both comparisons). Also in

Seaeero

[4

st
fc

or

ar
in

da
pa


~ ERLAUL LIBRARY

a

PHYSIOLOGICAL, BIOCHEMICAL, AND
PSYCHOLOGICAL RESPONSES IN AIR TRAFFIC
CONTROL PERSONNEL: COMPARISON OF THE 5-DAY

AND 2-2-1 SHIFT ROTATION PATTERNS

cant

C. E. Melton
J. M. MeKenzie
R. C. Smith
B. D. Polis*
E. A. Higgins
S. M. Hoffmann
G. E, Funkhouser
J. T. Saldivar
Civil Aeromedical Institute
Federal Aviation Administration
Oklahoma City, Oklahoma
* Aerospace Medical Research Department
U.S. Naval Air Development Center, Johnsville
Warminster, Pennsylvania

TBA

December 1973

Availability is unlimited. Document may be released
to the National Technical Information Service, Poe
Springfield, Virginia 22151, for sale to the public.

Prepared for
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION

Office of Aviation Medicine
Washington, D.C. 20591



T mood.
Melton,
1 rota-
tration,

TABLE VII
(Continued)

Mean Scores for the Overall Affect Index and the 15 CMACL Mood

Factors for Air Traffic Controllers Under Two Shift Rotation Schedules.

Schedule
5-Day 2-2-1
Ne20)

Factor Time (= 16)

Day Mid Day Evening Mid
Sleepy Pre 9.9 17.9 12.3 7.3 16.8
(4-36) Post 14.2 26.8 13.9 16.6 24.4
Social
Affection Pre 22.0 20.0 19.5 23.4 18.4
(4-36) Post 19.6 18.4 18.9 18.9 16.7
Surgency Pre 25.9 20.9 22.8 29.1 21.3
(5°45) Post 23.7 17.6 22.5 20.7 19.2
Vigor Pre 17.9 12.9 14.9 20.1 13.0
(327) Post 15.2 8.0 13.5 13.3 9.5
Zuckerman Pre 49.7 58.1 56.5 48.4 59.6
Affect Post 46.6 65.4 61.1 58.9 64.9
Adjective
Checklist
(21-189)

The values in parentheses represent

on each factor.
,

Social Affection, Vigor and Surgency scores be-
fore than after all types of shifts (p<.05 or
better for each comparison). Consistent with
these findings, scores for the Fatigue factor were
higher after shifts on both schedules. .

The scores for the Sleepy factor tended to be
higher for mid than for day shifts for both

edules (p<.01 for both comparisons).

It was noted from the 2-2-1 schedule data that
feelings tended % be more positive prior to
evening shifts than prior to the other two types
of shifts. This was true for the Concentration,
Social Affection, Vigor, Fatigue and Sleepy fac-
tors (p<.05 or better for each comparison).

the range of possible scores

However, postevening shift scores were essen-
tially equal to those from mid shifts in the
Sleepy and Fatigue factors, and were equal to
scores from both mid and day shifts on the re-
maining factors.

C. Attitude and Shift Experience Question-
naire. The mean ratings for both controller
groups on the four preshift and five postshift
questions are presented in Table VIII. Under
both rotation schedules, the controllers indicated
that they looked forward more to (question 1)
and had more enthusiasm for (question 2) day
shifts than mid shifts (p<.05 or better for each
comparison). Subjects on the 5-day schedule



for each comparison). In addition, scores on As noted in the analysis of controller mood
the Surgency factor obtained following mid data for the 5-day schedule (see Smith, Melton,
shifts tended to be higher on the 2-2-1 than the and McKenzie’), controllers on the 2-2-1 rota-
5-day schedule. tion also had higher Friendly, Concentration,

TABLE VII
Mean Scores for the Overall Affect Index and the 15 CMACL Mood

Factors for Air Traffic Controllers Under Two Shift Rotation Schedules.

Schedule
5-Day 2-2-1

Factor Time (N=16) (N=20)

Day Mid Day Evening Mid
Overall
Index Pre 7.43 6.86 7.00 7.43 6.81
(1-9) Post 7.05 6.42 6.87 6.74 6.43
Aggression Pre 8.4 9.9 8.2 9.5 8.2
(654) Post 762 8.3 8.8 9.5 8.7
Anxiety Pre 10.2 11.6 10.1 10.8 10.2
(7-63) Post 11.9 12.2 11.9 10.8 11.7
Anxious Pre 2.3 1.7 2.3 3.0 1.9
(1-19) Post 2.4 1.6 2.3 2.3 2.0
Concentra- Pre 53.8 49.3 43.8 53.1 38.8
tion (981) Post 44.1 41.4 41.1 42.1 36.4
Depression Pre 20.6 24.1 21.7 21.9 23.1
(12-108) Post 20.1 24.2 21.5, 22.4 21.4
Distrust Pre 4654 5.9 7.0 5.6
(3-27) Post 4.8 4.5 5.4 5.6 3.4
Dizzy Pre 5.0 5.6 4.3 5.1 4.6
(4-36) Post 54> 664 5.1 4.8 7.4
Fatigue Pre 19.4 32.4 24.8 16.6 30.6
(872) Post 25.1 45.4 26.9 30.7 42.5

’
Friendly 5 Pre 18.7 16.4 16.4 19.5 15.
(3-27) Post 15.7 14.2 15.9 15.6 14.3
Non-
cha lance Pre 9.3 9.4 7.9 8.9 8.5
(2-18) Post 7.6 9.4 7.9 8.6 8.2
8



boup. Day ag ae eo zg 28 2g
an 4 ae “as aN oie
elevated va da ae dei od at gg
difter- HHA tlt HIS HHI HHI HHI od
, however, B= ASF SRF SH AH= ASTM FE
RS ¢R SH gH Sa Su £8
aot
an
a0 2o ro or an an ay
SF $83 28 38 Ske SEs hs SS oF
wl oc oog eo oo So3 995 cg ea *}
Fle HID ttt ete HEI HHI HHI
23% 82% 25% Aa% 3g" ae" agy sae
an aa aa aa ry an aa aia
“
Na ex- RR SR BS, 28, fa AR RR 88 $
aN rMO AND NNO NNO NMO am nto i
a +1410 +1410 +1410 +1419 +1410 +1410 +141a +1410 #
BS] Saez naw ent |av naw naw gaz oaw 8
<4 et Pars 7% a4 brie ee Nt a
SS o6 63 gai Ra Sh od oo ge
ax an =] s a 33
ae
3
the basis ° By
day shift Al wa we
ay s a RS g aa 82 RR 8S SE aa
{} se gs S$ see ge $8 sg FSFE
3) 8s 88 | RS G55 BA SS Aas TE
that there Biel Hime titi FIFI 4141S FIFI F141 +1410 e223
difference 3 g| 83" 82% 8g gn# agY an* gaz an re
+ as total as eae 28 ae ed 2 oH rae
so * as 8&3 88 88 88 SS SR BR BES
However, > 3% S| 44 a3 Aa as ] as aa aa o
Be Gaus
differen- a 2a taza
. ; +
osphatidy] 3 oa : ss"
y suze
ma speci- a8 R&R S88 ee BA oR SR BR BR BEEK
in connec- Sa sa on Oe iS Si dn Or wont
s Sao 88s ss 885 98s 85 88a 88 ¢
ift of the 3 | 883 S55 S28 SNS BSG BR SNS AS aang
a wv BL tt4iS +1410 - FH 4S +141 HHO tI a EE
ospholipid Maan cau TH! amu tan ome man one
rk minus g] Re" BR" exe BET gah RAN BR” Be
a on rs ee oe 2 ee
Pa
terns are $3 $8 ga 88 s3 88 88 88
ficant dif- Sa 32 88 SR Re RR OF a8
or phos- *
Fy
4 3
4 33
Fy
zl $
fo scales of 2 ae
5 a4
I. There Hy ug
the anx- = ca
asa func- £e
w . : 2
al a SA S88 8S ga a Sh 8S Sang
schedules oat a oN St oe MM EN ied ¢
Bl oo | oe | SSB So ocB odB sc oo eeg &
than A- SB Fite Fitis HHO FIFI HHI FIFI HHI tH BB Fy
isons). In es} RS* SRF SAY AR= AG AHR“ SS* SATM Hoge
nificantly ¥ ab oan Aa oo aa oa oa oo co sero
fore shifts v Hage
233
). There AG aea8
23
“ 3S 7
or A-state BE] ka nave me moe me nae nwo mae PERS
mid shifts } 34 AAA <
oon
neces were unas
= 2 2 = a 2
a a a a = = = = aAada



PHYSIOLOGICAL, BIOCHEMICAL, AND PSYCHOLOGICAL RESPONSES
IN AIR TRAFFIC CONTROL PERSONNEL: COMPARISON OF THE
5-DAY AND 2-2-1 SHIFT ROTATION PATTERNS

I. Introduction.

{'.are,.variations.of the 2<2-.
or2 day-ehifts, 1 mid shift) ort hee
e(D consecutive days on the same shift)
fotations. When facility work load and stating
Mit, controllers will usually opt for the
px rotation in order to obtain the long week-
end that goes with it. The extended time be-
tween _work weeks results, obviously, from
wp? work periods during the week,

AUS. causing briefer.perieds (quick turnarounds)

between shifts than would otherwise occur (Fig.
1). When the straight 5-day pattern is em-
ployed, controllers work the same. 8-hour. shift
and have rs.off duty for 5 days; they then
is¥e"2 days off. On the 2-2-1 rotation, the con-
trollers normally work a different shift every
day. At Houston the work week consisted of the
1600-2400 shift on day 1, 1400-2200 on day 2,
0800-1600 on day 3, 0700-1500 on day 4, and
2400-0800 on day 5. Figure 1 shows that the
ties between shifts on the 2-2-1 pattern ranges
Q.to,15 hours, for an average of 12 hours;

thus a controller can put in # 40-hour week in
88 hours, leaving an 80-hour weekend. On the
straight 5-day rotation, 104 hours are required
to accomplish 40 hours of work. The.sveekend

rotation may be as long as 72 hours
See coming off a day shift returns to
ry ‘Shift, or as short as 56 hours if he

Seottits Back on a mid shift (Fig. 1).
“the ‘desirability of the 2-2-1 rotation is ob-
‘vious: the weekend is about 48% of the 7-day
(168-hour) wee the controller on the 5-day

rotation has a weekend that varies from 33% to
43% | of the 7- j-day week.

iiaine merally does not favor the
; _n, alleging that the quick turn-

around does not allow time for sufficient rest
between shifts. Certaifily, 9 hours between

~éhifte does not allow for 8 hours of bed rest when
2:- tite for travel and meals is considered, Con-

trollers say that the long weekend contributes to
a better life and that they return to work more
relaxed and refreshed than they do on the
straight 5-day rotation. Most controllers also
prefer the single mid shift feature of the 2-2-1
to the five consecutive mid shifts on the 5-day
rotation. That contention is supported by data
obtained in earlier studies* that showed five
days of shift work to be not long enough for
complete adaptation to night work but too long

abecause of the sccumulation of fatigue resulting

from poor quality daytime sleep.

A study of stress in air traffic control special-
ists at Houston Intercontinental Tower was car-
ried out in July and August 1970.4 At that time
the 5-day rotation pattern was in use. Later that
year the shift pattern was changed to the 2-2-1
rotation, thus affording an opportunity for study
of substantially the same group of controllers on
both rotations. The present study was carried
out in July and August of 1971. The purpose
of the experiment was to gempare the levels of
various stress indicators on the two shift rotation
patterns.

II. Methods.

Nineteen controllers volunteered to participate
in the study: twelve were journeymen, five were
supervisors, and two were trainees; twelve of
them had served as subjects on the previous
project. The techniques employed were the same
as those used on the 1970 project and described
in an earlier report Briefly, the éléctrocardi
gram was recorde tinuously on tape through?
out, every work |. Urine was collected by
each snbject ‘RGA he ‘ar086 each morning (speci-



IV. Discussion.

Physiological-Biochemical Measures

A. Mid shift. With regard to mid shift work,
the two rotation patterns can be differentiated
on the basis of heart rate. The mean heart rate
for all work positions for the entire week on the
5-day rotation was significantly lower than it
was for the one mid shift on the 2-2-1 rotation.
Heart rates during day work, however, were
equal on the two rotations, Since the mid shift
mean heart rate for all positions on the 2-2-1
rotation was equal to the day shift heart rates,
the difference is obviously due to depression of
the heart rate below the day rate (indeed, below
the prework rate) on the 5-day rotation rather
than to an elevation of heart rate above the day
rate on the 2-2-1 rotation. The reason for the
difference is not readily apparent; however, it
should be borne in mind that conditions on the
two rotation patterns are not strictly comparable.
When the daily means of heart rate on the 5-day
rotation are graphed, there is a linear increase
over the five mid shifts. The fifth mid shift
gives rise to a mean heart rate (76 bpm) that is
not significantly different from the mean heart
rate on the single mid shift on the 2-2-1 rotation
(81 bpm). Thus, the difference can probably be
accounted for by averaging of the heart rates
over the five mid shifts.

The urinary variables show that there are only
two points of significant difference between the
two groups, a significantly elevated adrenocorti-
cal response and a natriuresis on the 2-2-1 rota-
tion. The values for day sleep (M-3 specimens)
indicate that a week of mid shifts is about twice
as stressful as a week of work on the 2-2-1
rotation.

B. Day shift. The mean heart rates for all
subjects for all tower positions are equal for the
two rotation schedules.

Urine chemistry shows several points of sig-
nificant difference in response to work on the
two rotation schedules. Sympathetic arousal, as
indicated by norepinephrine excretion, is greater
on the 5-day rotatjgn than on the 2-2-1, Adre-
nocortical level of activity is significantly ele-
vated on the 5-day rotation. Though dietary
factors are difficult to assess, the excretion of
sodium is enhanced on the 2-2-1 rotation, sug-
gesting a reduced secretion of mineralocorticoids.

Plasma phospholipids are indicative only of
the entire week’s work, since blood specimens
were drawn on the first and last days of the shift.
The phosphatidyl glycerol data show that the
5-day rotation was significantly more stressful
than was the 2-2-1. It is important to note the
difference in phosphatidyl glycerol levels in the
prework specimens. The level of this stress in-
dicator is significantly lower in the controllers’
blood on the 2-2-1 rotation. This finding can
possibly be attributed to the extended weekend.
The amplitudes of the changes in phosphatidyl
glycerol levels are not significantly different over
the week’s work for the two rotation patterns.

Psychological Measures

The results indicate that controllers at this
facility find their work fatiguing, moderately
anxiety arousing, and satisfying. These trends
were present under both shift schedules, there
being relatively little difference between these
schedules on any of the measures obtained under
these schedules. There was some evidence that
affect states associated with day shifts were
somewhat less positive for the 2-2-1 than the
5-day schedules. However, this may have been
in part a function of the added assessment of
evening shifts for the 2-2-1 schedule. In other
words, the referent for this group may have been
somewhat different than for the 5-day group,
since no rating of evening shifts was obtained
for the 5-day schedule.

There was clear agreement that mid shifts are
associated with stronger negative feelings than
day or evening shifts. These data are thus con-
sistent with other findings’* concerning the atti-
tudes of controllers toward their work; it’ has
been" determined in the surveying of controllers.
&P°a Vartioty of facilities that the aspect of ATC.
Werk which they disliked the most, and signifi-

"more, than any other aspect of their work,

WES. working the mid shift. °
with respect to anxiety suggest
“tend to experience som t
aniniety” (A- -stite) while doing ATC work’
they do on the” average in other settings
Te However, the degree of anxiety ex-
perienced during work is probably well within
normal limits as the mean A-State Scale score
for the controllers corresponds to approximately
the 42nd percentile for normal college under-
graduate students. It also appears, at least by

12 .

a
SI

Fi

st


they did prior to the day shift. Assuming that
a controller worked mid shifts every 5th week,
an extrapolation of the sleep data shows that he
would sleep an average of 6 hours and 46 minutes
out of every 24 hours. On the 2-2-1 rotation he
would sleep an average of 6 hours and 35 min-
utes, a difference of 11 minutes per night over a
5-week period.

Strong managerial reasons may lead to the se-
lection of one or the other of the shift rotation
patterns, but physiologically and psychologically,
such a strong case could not be made at Houston.

Them. is no evidence thatcontrollers suffer un-
usual changes in anxiety, affect or attitude as a

function of working under either schedule. If a
hoice were to be made based on the controllers’

“physiological responses, it would have to be the

2-2-1 rotation. Studies similar to the one de-
scribed here are being planned at one or more
high-density facilities, employing different shift
rotation patterns. In those studies, data will be
collected on day, evening, and mid shifts on the
5-day rotation in order to provide a better com-
parison with the 2-2-1 rotation.

woe



ACKNOWLEDGMENT

The authors would like to thank Mr. Finis Wilcoxson, Chief, Houston
i Intercontinenta] Tower and Mr. Harry Witzel, Assistant Chief, for their

courtesies, consideration and interest throughout the course of these projects.
H Our special thanks go to the controllers who participated in the projects at
{ considerable sonal inconvenience and occasional discomfort, and to all the

other controllers whose thoughts offered on matters connected with these
projects contributed materially to our insights and interpretations,



TECHNICAL REPORT STANDARD TITLE PAGE

T, Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FAA~AM-73-22
T. Title ond Subtitle 3. Report Date

PHYSIOLOGICAL, BIOCHEMICAL, AND PSYCHOLOGICAL RESPONSES December 1973
IN AIR TRAFFIC CONTROL PERSONNEL: COMPARISON OF THE
5-DAY AND 2-2-1 SHIFT ROTATION PATTERNS

7. Authors)C, E. Melton, J. M. McKenzie, R. Cc. Smith, 8. Performing Organization Report No.
B. D. Polis, E. A. Higgins, S. M. Hoffmann,
G. E. Funkhouser, and J. T. Saldivar

6. Performing Organization Code

|

|

\ 9, Performing Organization Nome and Address 10. Work Unit No.

FAA Civil Aeromedical Institute

i P. O. Box 25082 TY. Contract or Grant No.

Oklahoma City, Oklahoma 73125
' 13, Type of Report and Period Covered
i 12. Sponsoring Agency Name and Address

Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S, W. 14, Sponsoring Agency Code
Washington, D. C. 20591

15. Supplementory Notes

Work was performed under Task AM-B-72-PHY-55 |

16. Abstract
Stress in controllers on the straight 5-day shift was determined at Houston Intercon-
tinental Tower in 1970, In 1971 controllers on the 2-2-1 rotation were studied at
the same tower. Controllers generally prefer the 2-2-1 to the straight 5-day sched-
ule because of the long week end associated with the 2-2-1. Management is concerned
that the "quick turnaround" on the 2-2-1 is a stressor that could compromise job per-|
formance. Physiological and psychological assessments showed no significant stress
differences on the two schedules. On neither of the schedules did the controllers!
stress levels differ from the general population, Urine and blood analysis showed
that day work on the 5-day rotation was generally more stressful than was the 2-2-1,
On the day shift on the 5-day rotation, controllers slept an average of 1 hour and
36 minutes longer per night than they did during a week on the 2-2-1. When on the
mid shift on the 5-day, controllers slept an average of 1 hour and 2 minutes less
per day than they did on the 2-2-1. Results of State-Trait Anxiety Index, Composite
Mood Adjective Checklist, and Attitude and Shift Experience Questionnaire showed:
(1) A-State > A-Trait, (2) "A-State > after work, (3) mood index < after work, (4) mood
index > for 5-day shift than for 2-2-1 day shifts, (5) mood index for mid shifts
lower than for day shifts, (6) attitudes and satisfaction favor day work, Controllerg
find their work fatiguing, moderately. anxiety arousing, and satisfying. It was
concluded that the stress differences on the two rotation patterns were too slight td
be of real significance and a choite between thenr would have to rest on managerial
considerations rather than biomedical ones.

17, Key Words 18. Distribution Stotement

v traffic controllers, stress, hormoneg Availability is unlimited. Document may bel
psychological tests, control towers, released to the National Technical Informa-
shift work & tion Service, Springfield, Virginia 22151,

for sale to the public.

19. Security Classil. (of this report) 2. Security Classil, (of this page) 21. No. of Pages [ 22, Price

16
Unclassified Unclassified $3.00

Form DOT F 1700.7 (s-69)



TABLE VIIE

Mean Rating for Preshift

and Postshift Questionnaire [tems

Rotation Schedule

S-da: 2-2-1
ATCSs ATCSs
(N=16) (N=19)
Day Mid Day Evening Mid
Pre-shif.
1. Looking
Forward to
Work 3.48 2.82 3.11 3.61 2.61
2. Enthusiasm 3.54 2.97 3.24 3.87 2.72
3. General
Feelings 3.78 3.20 3.53 4.11 3.39
Post-shift
1. General
Feelings 3.49 2.81 3.37 3.47 2.83
2. Tension 3.21 3.56 3.34 3.47 3.44
3. Feel Good
or Bad About
Shifts 3.80 3.32 3.42 3.53 3.28
4, Statisfac~
tion 4.00 3.51 3.53 3.63 3.33
5. Difficulty 2.77 3.75 3.19. 3.46 4.24

also indicated that their general feelings were
better before day than mid shifts (question 3);
however, there was no difference between these
shifts on this question for the 2-2-1 schedule.
On the 2-2-1 rotation it was also found that on
each of these three questions the evening shift
was pated significantly more positive than the
day shift. .

After shifts the findings for general feelings
(question 1) and shift difficulty (question 5)
were the same for both rotation schedules; feel-
ings were more positive, and shifts judged more
difficult for day than mid shifts. Under the

5-day schedule it was also found that satisfaction
with the shift (question 4) and positive feelings
about the shift (question 3) were greater for day
than mid shifts. There were no differences be-
tween types of shifts on these questions for the
2-2-1 rotation. It was also found that ratings
for the evening shifts were equal to the day shift
rating for each postshift item on this rotation
schedule.

There were no significant correlations between
responses to the questionnaires and STAI or
CMACL response trends.

5-4
(mi

*Si


: ae

TOTAL PHOSPHOLIPID AND PHOSPHATIOYL GLYCEROL
AS STRESS INDICES IN HUMAN POPULATION

TOTAL PHOSPHOLIPID P

CONTROLS

SIMULATEO
COMBAT FLIGHTS

SCHIZOPHRENICS

EXTENDED
COMBAT FLIGHTS.

O'HARE
CONTROLLERS

HOUSTON
CONTROLLERS

° 1000 © 2000 © 3000-4000
eMP/L

PHOSPHATIDYL GLYCEROL

*Coweat & —)
COMBAT FLIGHTS

SCHIZOPHRENICS

EXTENDED
COMBAT FLIGHTS

CONTROLS

‘
t

O'HARE
CONTROLLERS

HOUSTON
CONTROLLERS

° 20 40 60 80
BMEsL

= -Demorconon of significant difterences
Ot the Ie bevel

Fioure 2, Comparison of plasma phospholipids in var-
fous stressed and non-stressgd groups.

student standards, that general anxiety or A-trait
levels are quite low as the mean A-trait score for
controllers is equivalent to the 24th percentile
according to such normative data. It thus ap-
pears that while ATC work may cause some
moderate anxiety arousal in controllers, the re-
sulting anxiety level is well within “normal”
Imnits.

The major outeme of work appeared to be
increased feelings associated with fatigue; how-
ever, as noted, shift schedule had relatively little
effect on such feelings. The CMACL factors
which showed the greatest effects were thse as-
sociated with “physical” conditions such as

18

Sleepy, Fatigue, or Vigor. In addition, there
was evidence of decreased sociability at the end
of the shift. These effects were greater for the
mid shift, even though work load is lowest for
the mid shift, which suggests that boredom and
inactivity in a situation which demands vigilance
may be a most important factor in judged
“fatigue” level.

Sleep Patterns

While there are significant differences between
the two shift patterns reflected in the controllers’
body chemistry, generally favoring the 2-2-1
rotation, it should be carefully pointed out that
neither group significantly differed from the
general population. Under low-stress conditions
it would not be expected that any sort of opera-
tional deficiency would result from the shift ro-
tation pattern alone. However, in a high-stress
situation any additionally stressful factor would
be expected to increase the potential for error,
and it is commonly believed that the quick turn-
around feature of the 2-2-1 rotation constitutes
such an additional stress. It has been generally
assumed that controllers on the 5-day rotation
will utilize a full 8 hours of their 16-hour off
period for sleep, thus returning to work fully
rested and capable of meeting the most rigorous
demands of their job. The data for sleep pat-
terns indicate that such an assumption is not
entirely valid. It is of interest that most con-
trollers deliberately take only a short nap prior
to working the one mid shift on the 2-2-1 sched-
ule. They explained that by so doing they would
be tired enough at the end of the shift to sleep
well during thg day, then they would be rested
for the weekend and their normal day-night
schedule would not be seriously disrupted, Con-
trarily, on the 5-day rotation controllers com-
monly complained that after 5 consecutive mid
shifts their whole weekend was devoted to trying
to become readjusted to day wakefulness and
night sleep.

At Houston, when the 5-day rotation was in
effect, controllers worked a week of evenings,
then a week of days, then another week of eve-
nings, then another week of days, then a week of
mid shifts. Five weeks were required to com-
plete the entire pattern of duty -periods. Data
were not collected on evening shifts in that study ;
however, it is probably a valid assumption that
the controllers slept about the same amount as