Taste 7. Body Temperature

Difference
Time of Peak (hr/min)
Subj. Segment 1 Segment 2 Segment 3
No. (sb (82) (S3) $2_- Sl $3 - Sl
1 1825 0900 0359 -9/25 9/34
2 1629 0016 0359 7/47 11/30
3 1450 0009 0232 9/19 11/42
4 1727 0101 0605 7/34 12/38
5 1639 0407 0321 11/28 10/42
6 1543 0151 0211 10/08 10/28
7 1722 2107 0240 3/45 9/18
8 1450 2343 0344 8/53 12/54
9 1529 0329 0225 12/00 10/56
10 1609 2034 0123 4/25 9/14
lL 1550 2227 0200 6/37 10/10
12 1558 2339 0248 7/41 10/05
13 1504 2211 0214 6/67 11/10
4 1414 2024 0006 6/10 9/52
15 1550 0044 0258 8/54 11/08
Mean 1601 2247 0256 6/50 10/55

fatigue for the awake period was essentially
unchanged. However, the times during which
the subjects were most refreshed or most fatigued
did vary. Nine days were required for the fa-
tigue pattern to be reversed.

Realizing that the individuals rephased at
different rates and their peak responses occurred
at different times, we could not produce a mean
response curve for the physiological data because
averaging would tend to flatten the curves. We
chose, therefore, to look at the physiological data
of the subjects individually and report the total

number of individuals yielding a particular type
of response.

Those parameters that respond most rapidly
to stress demonstrated the shortest rephasal
times. Heart rate, which evidences almost im-
mediate response during stress, rephases in the
shortest time; rephasal was apparent on the first
day after the shift for nine of the subjects and
on the second day for the other six. This is
probably a result of the highly structured proto-
col. All activities were imposed on the 12-hour
shift in the same sequence. Participants were
given little choice of activities, since the majority

16


1830

SODIUM SUMMATION DIALS

0030

0630

1230

Ficure 8. Sodium summation dials for four representative subjects.

10


Taste 10. Norepinephrine

Difference
Time of Peak (hr/min)
Subj. Segment 1 Segment 2 Segment 3
No. (sl) (S82) (S83) $2 - Sl $3 _- S1
L 1607 0235 0059 10/28 8/52
2 1604 0232 0207 10/28 10/03
3 1119 0112 0149 13/53 14/30
4 1147 2235 0013 10/47 12/26
5 1216 2356 0000 11/40 11/44
6 1246 0125 0157 12/38 13/11
7 1219 0416 0323 15/57 15/04
8 1224 2322 2312 10/58 10/48
9 1649 0448 0153 11/59 9/04
10 1034 0101 0005 14/26 13/31
IL 1314 2325 0035 10/10 11/03
12 1232 0216 2314 13/44 10/43
13 1232 0058 0208 12/26 13/36
14* 1200 0205 0047 14/05 12/47
15 1152 0440 0246 16/48 14/54
Mean 1302 0138 0110 12/36 12/06
*

By summation-dial method demonstrated a random walk and is not included in

the mean values determined for this parameter,

for these two parameters. Subject 10’s data
were unusual. Although a new steady state ap-
peared to be established for all parameters, all
but one were only 135°, or 9 hours, out of phase
with night-sleep data. The indications were
strong that this individual would not accomplish
a 12-hour adjustment. Subject 14 produced data
with no recognizable pattern for almost all

20

parameters. From our observations of his be-
havior during the study, he did not appear to
adjust well to the laboratory setting nor to the
experiment protocol.

The general findings with the MTPB are con-
sistent with the previous findings with respect
to its sensitivity to time-of-day effects The
pattern of changes in performance associated


THE EFFECTS OF A 12-HOUR SHIFT IN THE WAKE-SLEEP CYCLE
ON PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES
AND ON MULTIPLE TASK PERFORMANCE

I. Introduction.

For many years biorhythms and the relation-
ship between biorhythms and performance have
generated a great deal of interest. In the past
several years, this interest has intensified due to
considerable changes in the human environment
and work situation. The FAA has had a con-
tinuing interest in this area for two basic reasons:
First, rapid air transportation across time zones
often necessitates a change in the traveler’s wake-
sleep cycle that consequently results in disrup-
tion of his biological rhythm patterns. Second,
the increasing number of tasks that must be per-
formed on a 24-hour basis has resulted in an
ever-larger work force of individuals who main-
tain, for varying periods, altered wake-sleep
cycles because of rotating shift patterns.

The study being reported here was designed
to evaluate the effects of alteration of the wake-

TasLe 1.

sleep cycle by 12 hours on physiological and
biochemical responses and performance and to
supply information concerning the time required
for adjustment of physiological rhythms to a
new “steady state” when the wake-sleep cycle is
altered.

Il, Materials and Methods.

Fifteen males paid volunteers, ranging in age
from 20 to 28 years, served as test subjects. They
were tested in groups of five on separate occa-
sions, and each group was confined to the lab-
oratory area throughout the test period. Prior
to the experiment each group spent approxi-
mately 75 hours in the laboratory for orientation
and indoctrination. During this time they be-
came proficient on the Civil Aeromedical Insti-
tute (CAMI) Multiple Task Performance
Battery (MTPB)? and the Kiigel apparatus and

Schedule of MIPB Tasks Performed in 1-Hour Test Session

Time in Minutes

0-15 15-30 30-45 45-60
Meters x x x x
Lights x x x x
Arithmetic x x
Problem Solving x x
Pattern Identification x xX
Tracking x

Note: X indicates task active,



MTPB Composite

530

-
@
3
S 520+
”
m SIOF
oO
Cc
So 500
i=
=
oO 490F
—
—_
ao 480+
o eo—e Pre Shift
- 470+ O—O Shift
3 A—A Days |I-3 Post
a 460} O—O Doys 4-6 Post
E %—@ Days 7-9 Post
450F
° ! N I I 14 | |
0630 0930 1230 1530 1830 2130 0030 0330 0630

Time of Testing

Ficure 10. Multiple Task Performance Battery mean composite performance scores as a function of time of test-
ing (n=15).

of the awake periods were occupied by activities
directly associated with the test situation, and
HR is highly influenced by activity levels.

The rephasal of catecholamines, which respond
less rapidly to stress than does HR, required an
average of 2.9 days for NE and 3.6 days for E.
The catecholamines do, however, respond more
rapidly to stress than do the other parameters
measured and did demonstrate the next shortest
rephasal times.

17

The times required for rephasal of K*, Na’,
and T,. were intermediate, with means of 4.4,
4.8, and 4.9 days respectively. The K* data
compare favorably with those reported by
LaFontaine et al.° In that study the subjects
were transported from Paris to Anchorage (11
time zones) and K* rephasal was accomplished
in 5 days. The T,. data exhibited a high degree
of variability, ranging from 2 to 8 days for
resynchronization; however, 11 of the 15 subjects



‘Taste 13. Summary Data for Complex Performance

CLOCK TIME 0630 0930 1230 1530 1830 2130 0030 0330 0630
PERIOD e, 2
Preshift 493 497. 503 519 511 9.23 <.10
Shift 508 486 467 5.20 £10
Postshift
Days 1-3 521 520 514 512 478 10.19 <.05
Days 4-6 514 501 506 506 499 6.56 Ns
Days 7-9 497 483 490 501 498 7.09 NS

rect effect of the time shift. Although subjects
in this kind of experiment typically look upon
the time shift as a challenge to their capabilities,
once they feel that they have successfully met
that challenge by demonstrating sustained, rela-
tively good levels of performance, there is a
strong tendency for a letdown to occur. The
remainder of the experiment becomes, in effect,
anticlimax. This would appear to be the most
likely and the parsimonious explanation of the
lowered performance levels during this final
portion of the experiment. This rationale is, of
course, directly related to our decision not to use
the data from the final day of testing in the
analysis. Although the shape of the perform-
ance curve for Days 7-9 is compatible with the
inference that rephasal of performance had
either occurred or was about to occur, the lack
of statistical significance leaves the issue unre-
solved. Our experience in this kind of research
suggests that subjects are typically unable to
sustain their motivation for this long a period
of removal from their normal social structure.
This problem, coupled with the above-mentioned
letdown phenomenon, makes the conduct of such
experiments and the interpretation of results
difficult.

Vv. Summary and Conclusions.

In our study of the effects of a 12-hour shift
in the wake-sleep cycle, we made the following
determinations: (1) According to the subjective
sleep survey, the total quantity and quality of
sleep did not change significantly when the wake-
sleep cycle was altered. (2) According to the

23

subjective fatigue index, the total fatigue for the
awake periods was not significantly changed;
however, the times within days for greatest fa-
tigue were altered and 9 days were required for
a complete reversal of the daily pattern. (3)
Of the physiological parameters measured, those
that make the most rapid response to stress re-
phased in the shortest period of time after the
shift. From shortest to longest mean rephasal
times, these were: heart rate, norepinephrine,
epinephrine, potassium, sodium, internal body
temperature, and 17-ketogenic steroids. (4)
Performance data based on the MTPB suggest
the following: (a) There was evidence of diurnal
variation during the preshift period. (b) There
were decrements on the day of the shift follow-
ing the short sleep period. (c) Performance
during the first 8 days following the shift was
relatively high for most of the day but was rela-
tively poor in the final session of the day. (d)
Performance for the fourth through sixth post-
shift days was average or above average for the
experiment with relatively small variations
among the five test sessions per day. (e) Per-
formance on the seventh through ninth postshift
days was below average for the experiment and
showed some evidence of a return to a diurnal
cycling pattern with a new peak period of per-
formance that reflected the 12-hour shift in the
wake-sleep schedule.

The implications of these findings are as fol-
lows: (1) Individuals making a 12-hour altera-
tion in the wake-sleep cycle should not perform
critical tasks during the first awake period fol-
lowing the change. Performance decrements



Taste 9. Epinephrine

Difference
Time of Peak (hr /min)
Subj. Segment 1 Segment 2 Segment 3
No. (sl) (S82) (S3) S2_- Sl $3 _- Sl
1 1532 2152 2350 6/19 8/17
2 1450 0250 0244 12/00 11/54
3 1410 0038 0349 10/29 13/39
4 1459 0122 0310 10/23 12/11
5 1541 01i2 0113 9/31 9/32
6 1304 2325 0025 10/21 11/21
7 1517 0022 0141 9/04 10/23
8 1520 0012 0404 8/52 12/44
9 1612 0220 0319 10/08 11/07
10 1410 2129 2348 7/19 9/38
ll 1434 0022 0328 9/48 12/54
12 1752 0105 0253 7/13 9/01
13 1442 2211 0125 7/29 10/43
14* 1602 0009 2102 8/07 5/01
15 1410 0007 0051 9/56 10/41
Mean 1502 0015 0203 9/13 11/01

* By summation-dial method demonstrated a random walk and is not included in
the mean values determined for this parameter.

chronization (6.8 days). This time is in line
with the findings in other studies.* +4

In considering patterns for the individual
subjects (Table 2), we noted that 10 of the 15
participants demonstrated a complete rephasal
for all physiological parameters measured. Sub-
ject 5 was similar in response to the majority
for all parameters except E. His E established

19

a new steady state, as did his NE, in only 1 day,
although it was not a complete 180° from base-
line. This may indicate some error in baseline
data. The 17-KGS data for Subject 15 produced
no recognizable pattern and no suitable explana-
tion is available at this time. Subject 1 demon-
strated very long rephasal periods (9 days) for
all but NE and HR with incomplete rephasal



Tasie 4. Percent of Power of Harmonics for Heart Rate and Body Temperature (Based on 96 Hours of Baseline

Data)
Harmonic 1 2 3 4 5 6 2 8 9-24 25-48
HR
% Power 2.06 1.24 0.92 55.33 1.77 0.84 0,90 13,38 11.58 11.98
Tre
% Power 2.39 2.53 3.08 51.56 2.19 1.44 0.83 10.84 13.40 11.80

These averages yield a different type of data
than those determined for the daily time-of-
peak ascertained for the summation-dial pre-
sentations. Tables 6 through 12 contain the
time-of-peak for the 24-hour harmonic for each
of the three 96-hour segments. For the baseline
period (Segment 1), NE had the earliest time-
of-peak (1302) and T,. was the last parameter
to peak (1601). All other parameters peaked
within the period between these two times. All
parameters approached a 12-hour change in
peak-response time between Segment 1 and Seg-
ment 3. The 17-KGS data, which demonstrated
the longest average time to rephasal by the
summation-dial technique, also demonstrated the
least change between Segment 1 and Segment 3
(10 hours 35 minutes).

C. Kiigel Apparatus Performance. The data
generated from the Kiigel task did not exhibit
statistically significant differences as a result of
the time shift. The automatic program designed
by the manufacturer did not provide an ade-
quately difficult task. The virtually perfect
levels of performance achieved by the subjects
on the Kugel apparatus tended to preclude the

possibility of detecting changes in this kind of
performance. Future studies should consider the
difficulty parameter of this task in such a way
that there will be room for performance changes.

D. Complea Performance. The data for per-
formance on the MTPB are summarized in Table
13 and shown graphically in Figure 10. Signifi-
cant differences (Chi square r) as a function of
time of day (test session) were found only for
the curve reflecting performance for the first 3
days after the shift. However, the time-of-day
effect approached significance for the 3 days
before the shift and the three sessions of the day
of the shift. In the case of the data for the day
on which the shift occurred, Sign tests were
used to compare the differences among the three
sessions, and these tests showed that the second
and third sessions differed significantly from the
first (p<.02) but not from each other. It would
appear that, in the case of the data for the first
3 postshift days, the major effect was depressed
performance during the fifth session of the day.
The Sign test confirmed this in showing that
performance in the fifth session differed signifi-
cantly from that in the fourth session (p<.02).

‘Tapie 5. Percent of Power of Harmonies for Urine Constituents (Based on 96 Hours of Baseline Data)
Harmonic 1 2 3 4 5 6 z 8
17-KGS
% Power 9.48 4.91 7.77 57.48 6.69 3.84 2.98 6.84
E
% Power 9.39 8.00 5.43 55.15 6.22 5.26 2.60 7.95
NE

% Power 16.41 12.34 8.61 33.06 8.60 3.93 5.08 11.96
Nat

% Power 12.17 6.50 3.48 60.46 3.37 3.81 2.92 7.29
ct

% Power 5.32 3.99 4.57 66.87 4.30 3.85 2.81 8.27

14


BODY

0030

1830

1230

10

TEMPERATURE SUMMATION

DIALS

0630

12

Ficure 4. Body temperature summation dials for four representative subjects.

sleep time-of-peak values. The subsequent 10
vectors represent day-sleep values.

Figure 3 presents summation dials for four of
the subjects for HR. The HR data indicate that
all subjects made a fairly rapid adjustment to
the shift change. The summation dials showed
a 180° change in direction for day-sleep time-of-
peak compared to night-sleep time-of-peak for
all subjects but Subject 10. Although Subject
10 quickly established a new “steady state,” the

direction of change was only about 135° (9
hours) from the night-sleep responses. The
complete reversal shown by the other three sub-
jects depicted in this figure are typical of the
responses of all other subjects. These data show
less variation between subjects and more rapid
adjustment than was anticipated.

Figure 4 presents the summation dials for T,..
In contrast to HR, T,. showed much variation
between subjects. One subject quickly shifted


NIGHT SLEEP DAY SLEEP
0600- — Arise, Urine, Fatigue Checklist, supper - Urine, Fatigue Checklist
4 Sleep Survey
{cr] wer
Breakfast aK
0900-4 K |—Urine, Fatigue Checklist q — Urine, Fatigue Checklist
4cp 4
Kk
1200 Lunch - Urine, Fatigue Checklist — Urine
3 cep 3
5 tk J
Z 15004 —Urine, Fatigue Checklist -Urine
x ce 7
s q
2 LK 7 . . . .
© 18004 Supper — Urine, Fatigue Checklist — Arise, Urine, Fatigue Checklist,
Sleep Survey
Ww tcp {cp
2 tk Breokfast
F 2100+ — Urine, Fatigue Checklist + K |-Urine, Fatigue Checklist
4 cP
aK
2400 — Urine —Lunch —Urine, Fatigue Checklist
cp
aK
0300 Urine 4 — Urine, Fatigue Checklist
cP
4K
0600

CP = Complex Performance
K = Kigel

Ficure 1.

the wake-sleep cycle had little effect on either
the total quantity or the quality of sleep. Dur-
ing the night-sleep segment the subjects slept, on
the average, 91 to 96 percent of the sleep period
with almost 50 percent being deep sleep. During
the first day-sleep period all subjects but one
reported sleeping the entire period. The average
time asleep for all day-sleep periods exceeded 95
percent. Therefore, it would appear that all
subjects adjusted quickly to the new time for
sleeping.

The responses to the fatigue survey presented
a different picture (Figure 2). These responses

Schedule of events.

were recorded six times a day during the awake
periods at 3-hour intervals, the first survey being
completed upon awakening. The possible scores
ranged from 0 (completely fatigued) to 20 (fully
refreshed). The mean scores for the night-sleep
period ranged from 10.2 to 10.4, The mean
scores for the day-sleep periods ranged from 9.1
to 10.5. Although the daily means for night
sleep and day sleep did not vary greatly, the
time of day for lowest scores was different.
After night sleep, the lowest scores were at 0600
each day, the first response of the day, indicating
that the subjects did not feel fully refreshed



became acquainted with the experiment protocol.
After a 2-day break they began the 15-day ex-
periment period. On Days 1 through 5 the
subjects worked during the day and slept at.
night (2230 to 0600) except on the fifth night,
when they slept only 3 hours (2100 to 2400).
On Day 6 the subjects began a new wake-sleep
eycle, changed by 12 hours, in which they slept
during the day (1030 to 1800) and worked at
night. The subjects followed this day-sleep
routine for 10 days.

The subjects were tested daily on the CAMI
MTPB in five 1-hour sessions at 3-hour intervals.
On preshift days the first session began at 0630
and the fifth session began at 1830 and ended at
1930. On the day of the time shift the subjects
were tested at 0030, 0330, and 0630. After the
time shift they were tested five times beginning
at 1830 and ending at 0730 the following morn-
ing. Each session consisted of a fixed sequence
of tasks as shown in Table 1. During each 15-
minute subperiod, the subjects performed the
indicated combination of tasks. The nature of
the individual tasks and the performance meas-
ures ‘derived from each are described in detail
elsewhere” and will not be discussed here. The
measure used to reflect the possible changes in
performance was a composite score to which
each of the measures from the individual tasks
contributed equal variance. The grand mean of
the composite score was set to equal 500 with a
standard deviation of 10. For the purpose of
analysis as well as the presentation of data,
scores were combined over 3-day blocks. (The
data for Days 1 and 2 were not used because of
residual learning effects.) Namely, the perform-
ance data for the first daily session were aver-
aged over Days 3, 4, and 5, and corresponding
averages were computed for the four remaining
daily sessions. The data for the three test ses-
sions occurring on the day of the shift were
treated individually. The data for the five daily
sessions for Days 6 through 14 were also aver-
aged in 3-day blocks; data for the final day were
not used because of the likelihood of end-of-
experiment effects.

The Kiigel test estimates psychomotor per-
formance. The “Kiigelmaschine” is a horizontal
rotating cylinder containing a row of five holes
of graded sizes. Three sets of five steel balls
corresponding in size to the holes in the cylinder
were placed in a tray attached to the machine

2

near the base of the cylinder. The test subject,
seated in front of the tray, was instructed to
pick up and insert, as rapidly as possible, the
correct ball into a corresponding row of station-
ary holes lined up with those of the rotating
cylinder. Cylinder speed was programed to
accept 40, 50, 60, 70, 60, 50, and 40 balls per
minute. Scores were automatically recorded on
an attached strip chart. A stylus marked a short
horizontal line only when a ball was dropped
into a hole of the corresponding size. The final
score was the sum of the scores at each cylinder
speed.

Heart rate (HR) and body temperature (Tye)
were measured hourly during the entire test
period. Dry silver electrodes? attached to the
CM, position were connected by wires to an
Avionics Electrocardiocorder and HR responses
were recorded on electromagnetic tape. Tape
and batteries were replaced each 24 hours. Al-
though HR was recorded continuously, only
hourly averages were statistically analyzed.
Rectal temperature was measured with a therm-
istor probe inserted 10 cm into the rectum.
Values were read to the nearest 0.1° C with a
portable bridge.

Urine was collected every 3 hours throughout
the experiment period. The volumes were re-
corded, and aliquots were taken, preserved with
boric acid and 1.2 N hydrochloric acid, and
frozen for later biochemical analyses. Urinary
catecholamines* and 17-ketogenic steroids’ were
determined by using Technicon Autoanalyzer
systems. Sodium and potassium were measured
with an Atomic Absorption-Emission Spectro-
photometer (Instrumentation Laboratory, Inc.,
Model 853).

Subjective questionnaires included the 10-item
Fatigue Checklist developed by Pearson and
Byars” and the Sleep Survey developed at the
USAF School of Aerospace Medicine that re-
flected the test subjects’ judgment on both the
length and quality of sleep the previous night.

A schedule of these events showing the times
at which they occurred during the control period
and also during the period after the change is
presented in Figure 1.

Ill. Results.

A. Subjective Forms. According to results of
the Sleep Survey, the alteration by 12 hours of


TaBLe 6. Heart Rate

Difference
Time of Peak (hr/min)
Subj. Segment 1 Segment 2 Segment 3
No. (sl) (82) (s3) S2_- Si s3_- Sl
1 1514 0138 0138 10/24 10/24
2 1429 0209 0135 11/40 11/06
3 1408 0005 0150 9/57 11/42
4 1337 0049 0125 11/12 11/48
5 1313 0016 0033 11/03 11/20
6 1308 2334 0020 10/26 11/12
7 1353 0027 0137 10/14 11/34
8 1343 2257 0104 9/14 11/21
9 1458 0040 0128 9/46 10/30
10 1435 2221 2357 7/26 9/22
il 1434 0025 0135 9/31 11/01
12 1358 0020 Olll 10/22 11/13
13 1331 2344 0046 10/13 11/15
14 1328 0002 2356 10/34 10/28
15 1451 0140 0243 10/53 11/52
Mean 1408 0020 0111 10/12 11/03
The general pattern of the curves suggests the day. (5) Performance on the seventh through

following: (1) Performance showed evidence of
diurnal variation during the preshift period.
(2) There were decrements on the day of the
shift following the short (3-hour) sleep period.
(3) Performance during the first 3 days follow-
ing the shift was relatively high for most of the
day but was relatively poor in the final session
of the day. (4) Performance on the fourth
through sixth postshift days was average or
above average for the experiment with relatively
small variations among the five test sessions per

15

ninth postshift days was below the average for
the experiment and showed some evidence of a
return to a diurnal cycling pattern with a new
peak period of performance that reflected the
12-hour shift in the work-sleep schedule.

IV. Discussion.

The sleep surveys indicated that the total
quantity and quality of sleep did not change
when the sleep cycle was altered by 12 hours.
Also, the fatigue surveys indicated that total



1830

HEART RATE SUMMATION

0630

1230

Ficure 3. Heart rate summation dials for four representative subjects.

5

DIALS



Tape 11, Sodium
Difference
Time of Peak (hr /min)
Subj. Segment 1 Segment 2 Segment 3
No. (S1) ($2) (83) $2_- SL $3 - Sl
1 1129 1228 2236 0/59 11/07
2 1615 0501 0449 12/46 12/34
3 1458 0514 0420 14/16 13/22
4 1533 0812 0346 16/39 12/13
5 1644 0523 0455 12/39 12/11
6 1547 0200 0244 10/13 10/57
7 1639 0515 0526 12/36 12/47
8 1632 0052 0459 8/20 12/27
9 1518 0234 0307 11/16 11/49
10 1546 1339 0125 -2/07 9/39
11 1608 0257 0355 10/49 11/47
12 1746 0350 0429 10/04 10/43
13 1457 0046 0258 9/49 12/01
14* 1805 1069 0723 -7/24 13/18
15 1622 0054 0258 8/32 10/36
Mean 1544 0131 0328 9/47 11/44

* By summation-dial method demonstrated a random walk and is not included in
the mean values determined for this parameter.

with the postshift phase of the experiment is
suggestive of a sleep-loss phenomenon. This is
seen directly in the data of the three sessions on
the day of the shift when, in fact, there was an
important decrease in the time available for
sleep. The data for the first 3 full days follow-
ing the shift suggest that the shift in the time
at which performance was required did not have

21

a detrimental effect except for the last session
of the day. It is also relevant that this last ses-
sion began 1214 hours after the end of the last
sleep period. ‘Thus, the “length of the workday”
may have been responsible for the downturn of
the curve of the preshift performance on the
last. daily session, and the poor performance on
the last daily session of the first 3 days after the



Technical Report Documentation Page

T. Report No. 2. Goverament Accession No. 3. Recipient's Catalog No.
FAA-AM-75-10

4. Title and Subtitle 3. Report Date

THE EFFECTS OF A 12-HOUR SHIFT IN THE WAKE-SLEEP CYCLE

ON PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES AND ON 6. Performing Organization Code

MULTIPLE TASK PERFORMANCE

[8. Performing Organization Report No

Tn Ey A, Wiggins, W., Chiles, J. Mekenzte,
. F. Tamptetro, C; M.’Winget, G. E. Funkhouser,
Mi Ji Burr, J. A. Vaughan,”and A! E; Jennings

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute
P. O. Box 25082 TI. 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 Administratio
800 Independence Avenue, S.W, 14." Sponsoring Agency Code
Washington, D.C, 20591

OAM Report

15. Supplementary Notes

Work was performed under Task AM-B-73-PHY-67.

16. AbstractPifteen male paid volunteers (ages 20 to 28) were studied in three groups

of five each, The first 4 days of the experiment they slept nights (2230 to 0600)
and worked days. On the fifth night, they slept only 3 hours (2100 to 2400) before
starting a 10-day period in which the wake-sleep cycle was altered by 12 hours.
According to a subjective sleep survey, the total quantity and quality of sleep did
not change significantly when the cycle was altered. According to the subjective
fatigue index, the total fatigue for the awake periods was not significantly changed;
however, the times within days for greatest fatigue were altered and 9 days were
vequired for a complete reversal of the daily pattern. Of the physiological param-
eters measured, those making the most rapid response to stress rephased in the
shortest period of time after the shift. From shortest to longest mean rephasal
times, these were: heart rate, norepinephrine, epinephrine, potassium, sodium,
internal body temperature, and 17-ketogenic steroids. Performance data based on the
Civil Aeromedical Institute Multiple Task Performance Battery suggest the following:
(1) There was evidence of diurnal variation during the preshift period. (2) There
were decrements on the day of the shift following the short sleep period. (3) Perform
ance during the first 3 days following the shift was relatively high for most of the
day but was relatively poor in the final session of the day. (4) Performance on the
fourth through sixth postshift days was average or above average for the experiment
with relatively small variations among the five test sessions per day. (5) Perform-
ance on the seventh through ninth postshift days was below average for the experiment
and showed some evidence of a return to a diurnal cycling pattern with a new peak
period of performance that reflected the 12-hour shift in the wake-sleep schedule.

17. Key Words 18, Distribution Statement
Circadian rhythms, Complex performance, Document is available to the public through’
Heart rate, Rectal temperature, Urinary | the National Technical Information Service,
stress indicators, Wake-sleep cycles Springfield, Virginia 22151
19. Security Clossif. (of this report) 0. Security Classif. (of this page) Di. No. of Pages | 22. Price
$3.00 PC
Unclassified Unclassified .95 ME

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



NOREPINEPHRINE SUMMATION

1830

1230

DIALS

0630

Ficure 6, Norepinephrine summation dials for four representative subjects.

180° from baseline (2 days). Three subjects
also shifted 180°, but less rapidly (3 to 4 days).
Three other subjects, typified by Subject 9, made
irregular loops but did rephase. Four subjects,
as exemplified by Subject 12, made broad curves,
rephasing over a 5- to 6-day period. One subject
did not return a full 180° but appeared to be
changing at the end of the experiment. The T,,
of Subject 1 changed slowly but continuously
and by the end of the 10th day after the change

had shifted 14 to 15 hours. Subject 10 had a T,.
response that, as was the case with his HR curve,
reached a steady state of only about 135°.

The next five figures present the results of
data obtained from urine excretion values. Uri-
nary epinephrine (E) is presented in Figure 5,
norepinephrine (NE) in Figure 6, 17-ketogenic
steroids (17-KGS) in Figure 7, sodium (Na*)
in Figure 8, and potassium (K*‘) in Figure 9.
We did not anticipate that these data would be


1830

EPINEPHRINE SUMMATION

0039

063

1230

Fieure 5. Epinephrine summation dials for four representative subjects.

7

DIALS

14



SUBJECTIVE FATIGUE CHECKLIST

207
NIGHT SLEEP
ie
1oF
st
Day DAY 2 DAY 3 a
° eee Porch recite sd
299000 200000 00000 000000 000000
898955 550000 250006 S90000 o00006
DUOG— oOANwo-— DAHO- GFNHH- OONHHO—
Co--=s Gott fa O-5=8 CO-==N Sot HtaA
20
15
w
a
OQ 10F
°°
77)
5b : £
DAY 6 :
° renee s eae:
©99000 9000000 000000 000000 00000
688888 883888 888S88 888888 858888
D-FOOH O-~FMHOH B-THOH B-FHGOH O-FMOH
=NNOGOO =“NOG0 =~WNNOOO0 -ANNOOO =NNOOO
207
DAY SLEEP
Is-
lof
sb
DAY ID DAY 12 DAY 13 DAY 14 DAY 15
° SESE a Sa 8 S Bes cote 3 B hen Se B eee Ses Sa
090000 000000 000090 Go0000
883883 388333 ssssss gegsss ssees
= = Oem OR wl a
Fak6S5 FANGSG Fanddd WAASSS 2aass

TIME (CLOCK HOURS)

Figure 2.

Mean score of Subjective Fatigue Checklist as a function of time of day for 15 consecutive days

(n= 15).

upon awakening. The next lowest score was the
last. response of the day (2100). The scores at
0900 and 1200 were similar and were the highest
of the day. For the day-sleep periods, the first
response upon awakening (1800) was relatively
high the first day after the cycle change but
showed a continuous, gradual decline each day
to the end of the study. It was not until 9 days
after the change that the first response upon
awakening from day sleep reached the same level
as the first response upon awakening from night
sleep. The highest scores during the day-sleep
periods were at 3 hours after awakening (2100),
and the subjects consistently indicated the great-

est feeling of fatigue at 0900, the last response
before retiring. In general, the subjects felt
more refreshed upon awakening from day sleep
than from night sleep. However, they tended
to indicate greater fatigue toward the end of the
awake period when sleeping days. The greater
the number of days spent at day sleep, the more
closely the day-sleep responses approximated a
12-hour reversal of the night-sleep responses.

B. Physiological Responses. All physiological
responses were measured at equal time intervals
throughout the study and could thus be subjected
to treatment by the summation-dial method.’
The first four vectors of the dials are night-


TaBLe 8. 17-Ketogenic Steroids

Time of Peak

Difference

Subj. Segment 1 Segment 2 Segment 3
No. (Sl) (S82) (S83) $2 - Sl $3 - Sl
1 1049 1516 2035 4/26 9/46
2 1352 0114 0100 11/23 11/08
3 1316 1020 0049 2/55 11/33
4 1505 1738 0139 2/34 11/34
5 1434 OS511 0047 14/37 11/13
6 1226 1848 0033 6/22 12/07
7 1407 1923 2338 5/17 9/31
8 1533 1835 0209 3/02 10/36
9 1428 1520 0037 0/52 10/08
10 1553 1230 2210 -3/21 6/16
ll 1351 2140 0226 7/49 12/35
12 1247 1823 0013 5/36 11/26
13 1237 0325 2221 14/48 9/44
14% 1458 1048 1542 -4/10 0/44
15* 1620 0101 0239 8/41 10/19
Mean 1347 1913 0014 5/25 10/35

* By summation-dial method demonstrated a random walk and is not included in
the mean values determined for this parameter.

rephased in 4 to 6 days. Our mean rephasal time
of T,, is in fair agreement with one reported
study in which reversal of diurnal temperature
rhythms occurred within 3 to 4 days after a 12-
hour time shift. Other studies,‘*1* however,
report a longer time for reversal. These differ-
ences might be accounted for by the fact that,
in our experiment, the aspects of the temperature

18

measurement considered for determining the
time for rephasal were different from those con-
sidered in the experiments of others. In our
appraisal, we considered only the time-of-peak
response in determining rephasal; in other
studies, phase angle was the chief consideration.

Of the parameters measured in this study, 17-
KGS required the longest mean time for resyn-


observed during this first period might be due
to either the sleep loss or the initial adjustment
to the new schedule, or both factors could be
contributory. (2) After the first full sleep
period following the change, subjects appeared
to perform well even though the physiological
and biochemical parameters measured were still
adjusting to the change. (8) For the first week

following the change in the wake-sleep cycle,
individuals should not work longer than 8 hours
continuously because performance deteriorates
after that time. After the change, subjects ap-
peared to fatigue more readily toward the end
of the awake period than they did normally.
This effect was ev'dent for several days after
the change.

References

n

. Chiles, W. D., E. A. Alluisi, and 0. §, Adams: Work
Schedules and Performance During Confinement,
HUM. FACTORS, 10 :143-196, 1968.

. Chiles, W. D., A. E. Jennings, and G. West: Multiple
Task Performance as a Predictor of the Potential
of Air Traffic Controller Trainees. FAA Office of
Aviation Medicine Report No. AM-72-5, 1972.

3. Conroy, R. T. W. L.: Circadian Rhythm of Plasma
Corticosteroids During the Imposition of a 12 Hour
‘Time Schedule, J. PHYSIOL, 194:19P-20P, 1967.

. Elliott, A. L., J. N. Mills, D. S. Minors, and J. M.

Waterhouse: ‘The Effect of Real and Simulated

‘Time-Zone Shifts Upon thé Circadian Rhythms of

Body Temperature, Plasma 11-Hydroxycorticoster-

oids, and Renal Excretion in Human Subjects, J.

PHYSIOL, 221 :227-257, 1972.

Few, J. D.: A Method for the Analysis of Urinary

1T-Hydroxycorticosteroids, J. ENDOCRINOL, 22:31-

46, 1961.

. Fiorica, V., and R. Moses: Automated Differential
Fluorometric Analysis of Norepinephrine and Epine-
phrine in Blood Plasma and Urine, BIOCHEM.
MED., 5 :483-504, 1971.

. Hetherington, N, W., C. M. Winget, L. S. Rosenblatt,
and P. B. Mack: The Summation Dial, a Vectorial
Representation of Time Series Data, J. INTER-
DISCIP, CYCLE RES., 2:365-877, 1971.

8. Klein, K. E., H. M. Wegmann, and B, I. Hunt:

Desynchronization of Body Temperature and Per-

formance Circadian Rhythms as a Result of Out-

going and Homegoing Transmeridian Flights,

AEROSPACE MED., 43 :119-182, 1972.

N

-

ad

-

a

9. LaFontaine, E., J. Lavernhe, J. Courillon, M. Med-
vedeff, and J. Ghata: Influence of Air Travel Hast-
West and Vice-Versa on Circadian Rhythms of
Urinary Excretion of Potassium and 17-Hydroxy-
corticosteroids, AEROSPACE MED., 38 :944-947, 1967.

10, Pearson, R. G., and G. E. Byars, Jr.: The Develop-
ment and Validation of a Checklist for Measuring
Subjective Fatigue. USAF School of Aerospace
Medicine Report No, TR~56-115, 1956.

11. Perkoff, G. R., K. Eik-Nes, C. A, Nugent, H. L. Fred,
R. A. Nimer, L. Rush, L. T, Samuels, and F. H.
Tyler: Studies of the Diurnal Variation of Plasma
17-Hydroxycorticosteroids in Man, J, CLIN, ENDO-
CRINOL. METAB., 19 :432—-443, 1959.

12. Saldivar, J. T.: Simplified Technique for Application
of Dry ECG Electrode, AEROSPACE MED., 41 :456—
457, 1970.

18, Sharp, G. W. G.: Reversal of Diurnal Temperature
Rhythms in Man, NATURE, 190 :146-148, 1961.

14. Sharp, G. W. G., S. A. Slorach, and H. J. Vipond:
Diurnal Rhythms of Keto- and Ketogenic Steroid
Excretion and the Adaptation to Changes of the
Activity-Sleep Routine, J. ENDOCRINOL. 22:377-
385, 1961,

15, Weitzman, E. D., D. F. Kripke, J. Krean, P. Me-
Gregor, and L, Hellman: The Effect of a Prolonged
Non-Geographic 180° Sleep-Wake Cycle Shift of
Body Temperature, Plasma Growth Hormone, Corti-

ol, and Urinary 17-OHCS, PSYCHOPHYSIOLOGY,

7 :307, 1970.

24




1830

POTASSIUM SUMMATION DIALS

0030

0630

Figure 9. Potassium summation dials for four representative subjects.

ll



sleep (baseline) period, Segment 2 was the first
4 days after the 12-hour shift in the wake-sleep
cycle, and Segment 3 was the last 4 days of the
study (the 7th through 10th day after the re-
versal). The analyses were accomplished with
8 harmonics for the urine data and 48 harmonics
for HR and T,.; the fourth harmonic was the
24-hour harmonic. In each of the seven param-
eters reported, the fourth harmonic exhibited the
greatest percent of power and thus verified the
24-hour circadian rhythm. Table 4 presents the
percent of power for the HR and T,. harmonics.

Harmonics 9 through 24 and 25 through 48 were
summed for simplicity of presentation. Table 5
gives the percent of power for the eight har-
monics determined for the urinary constituents.
These values are presented for the 96-hour night-
sleep period. The electrolytes demonstrated the
greatest percent of power for the fourth har-
monic with NE having the least powerfully de-
fined 24-hour periodicity.

Another facet, determined through the data
analyses of the 96-hour segments, was the aver-
age time-of-peak for each of the 4-day periods.

Taste 3. Summation-Dial Rephasal Patterns

By Parameter

&R ik Rw
HR 14 1 0
Tre 13 2 0
17-KGS 12 1 2
E i 3 1
NE 13 1 1
nat 12 3 0
xt 12 2 1
Totals 87 13 5
By Subject
Subj. No. CR IR RW Subj. No. CR IR RW Subj. No. CR IR RW
1 5 2 0 6 7 0 0 11 7 0 0
2 7 0 0 7 7 0 0 12 7 0 0
3 7 0 0 8 7 0 0 13 7 0 0
4 7 0 0 9 7 0 0 14 1 2 4
5 6 1 0 10 1 6 0 15 4 2 1
CR = Complete rephasal (180° change)
IR = Incomplete rephasal (new steady state, less than 180°)
RW = Random walk (no regular pattern to change)

13



Acknowledgment

The authors gratefully acknowledge the contributions of Mr. Norris
Hetherington and Dr. Leon Rosenblatt of Geneticon for their work with the
physiological and biochemical data in the preparation of the summation
dials. They are also thankful to Ms. Patsy Fowler, Mr. Russell Moses, and
Mr. Noal May of the Aviation Physiology Laboratory’s Stress Analysis
Research Unit for their biochemical analyses of the urine. They also wish
to thank Ms. Georgetta West and Mr. Steve Burke of the Aviation Psychol-
ogy Laboratory’s Human Performance Research Unit for their competent
administration of the CAMI Multiple Task Performance Battery.



Taste 12, Potassium

Difference
Time of Peak (hr/min)
Subj. Segment 1 Segment 2 Segment 3
No. (sl) (S2) ($3) $2 - Sl $3 - Sl
1 1056 1335 1902 2/38 8/06
2 1259 0119 0112 12/19 12/13
3 1329 0758 0225 18/29 12/56
4 1344 1934 0100 5/50 11/16
5 1338 0423 0026 14/44 10/47
6 1354 2301 2354 9/07 10/00
7 1419 0043 0159 10/25 11/41
8 1310 2125 0049 8/16 11/39
9 1304 0045 0056 11/41 11/52
10 1438 1427 2305 -0/11 8/28
11 1432 2147 0002 7/1S 9/31
12 1325 0044 0105 11/20 11/41
13 1155 1045 2309 -1/10 11/14
14* 1344 1033 1740 “3/11 3/56
15 1328 2332 0022 10/04 10/54
Mean 1322 2200 0011 8/38 10/53

*

By summation-dial method demonstrated a random walk and is not included in

the mean values determined for this parameter.

shift may have been simply a substantial exag-
geration of that effect. Although the subjective
reports of the subjects did not suggest that the
quality of sleep was appreciably poorer during
the early days after the shift, any tendency in
that direction would likely make the day seem
somewhat longer to the subjects.

22

By the time that the fourth, fifth, and sixth
postshift days had been reached, the subjects
were able to maintain. their performance at or
above the average for the experiment. The de-
pressed levels of performance on the seventh
through the ninth days after the shift should not
necessarily be regarded as suggestive of any di-




I7-KETOGENIC STEROIDS SUMMATION DIALS

0030

1830 0630

1230

Fieure 7. 17-Ketogenic steroids summation dials for four representative subjects.

9



as precise as the HR and T,, data, which were
reported 24 times daily for a more precisely
defined curve, as opposed to the urinary data,
for which values were determined only eight

times each day.

Table 2 indicates the number of days to re-
phasal, by subject, for each of the physiological
parameters measured. The notation “IR” beside
a number indicates incomplete rephasal; ie, a
new pattern was established but it was not 180°
from the baseline days. The notation “RW”
stands for random walk, or a pattern that was

TaBLe 2. Number of

so variable as to establish no definable trend.
All other numbers represent 180° reversal of the
time-of-peak values. Table 3 presents the re-
phasal pattern, first by the parameter measured
and then by subject.. Subject 10 demonstrated
IR for all parameters but NE. Subject 14 dem-
onstrated RW for four parameters.

Fourier analyses were accomplished for the
data by using three 96-hour segments. Each
segment contained 97 data points for HR and
T,. and 33 data points for the urinary constitu-
ents. Segment 1 was the last 4 days of the night-

Days for Rephasal

Subj.
No. HR Tre E NE 17-Kcs Nat a
1 1 7 9 IR 2 9 9 9 IR
2 1 2 4 2 6 3 4
3 2 3 5 1 5 6 5
4 1 6 3 3 5 5 5
5 1 4 1 IR l 7 3 3
6 2 4 1 1 6 4 4
7 2 4 3 5 8 5 3
8 2 4 5 2 5 5 5
9 2 4 5 4 6 4 3
10 1IR 6 IR 1 IR 2 8 IR 7 IR 5 IR
IL 1 5 1 5 9 5 5
7 1 5 4 6 7 3 3
13 2 5 7 1 7 5 5
14 1 8 IR RW RW RW 5 IR RW
15 1 6 1 6 IR RW 3 IR 2
Mean 1.4 4.9 3.6 2.9 6.8 4.8 44
Range 1-2 2-8 1-9 1-6 5-9 3-9 2-9

IR = Incomplete rephasal (not 180°)

RW = Random walk

12