Sleep, 1(3):319-325
© 1979 Raven Press, New York
The Stability and Variability of Dreaming
Milton Kramer and Thomas Roth
Dream-Sleep Laboratory, Veterans Administration Hospital.
Cincinnati. Ohio
Summary: To examine the stability and variability of psychological dreaming,
we collected dream content from the end of the first four REM periods of the
night for 20 consecutive nights from 14 volunteers, The dreams were scored for
characters, activities, and descriptive elements utilizing the Hall- Van de Castle dream content scoring system, We were able to recover an adequate amount
of dreaming (76% recall) from our awakenings and to achieve an adequate level
of scoring reliability (91% agreement). Mean content was stable, as the mean
overall night to night significant correlation of 0.46 reflects, yet variable enough
(79% of the variance is unexplained) to be reasonable and manageable (3 to 15
items per night). Adaptation in dream content did occur as reflected (I) in all
four second week content correlations being significant and larger than the
nonsignificant first week correlations, and (2) in nights 19 and 20 being highly
correlated and significant, whereas nights I and 2 were not; nights 10 and II,
while nonsignificant, were at an intermediate level. We conclude that dreaming
is both a stable and variable phenomenon that shows clear evidence of adaptation across nights. Key Words: Dreams, laboratory-Dream content scoringReliability of dreaming-Stability of dreaming- Variability of dreaming.
The stability and variability of psychological dreaming are of considerable
interest to both the dynamic psychotherapist and the sleep scientist. The
psychotherapist is concerned with the stability-variability dimension in dreaming, since it is the dimension central to the manner in which he will utilize the
dream in treatment. The sleep scientist finds the stability-variability dimension of
great moment, since it is the dimension that determines whether dreaming will be
the object of further scientific examination.
The psychotherapist has assumed in his utilization of the dream that it is both a
stable and a variable process. He treats the dream as stable when he utilizes the
dream to make diagnostic statements about the dreamer. He treats the dream as
variable when he explores the dream in treatment as responsive to some immediate concern or circumstance in the dreamer's life. The psychotherapist, therefore,
Accepted for publication March 1979.
Address reprint requests to Dr. Kramer at Dream-Sleep Laboratory, Veterans Administration
Hospital, 3200 Vine Street, Cincinnati, Ohio 45220.
319
320
M. KRAMER AND T. ROTH
operates with the dream as if it were potentially revelatory of both the trait and the
state aspects of personality, i.e., both stable and variable.
The sleep scientist is also interested in the stability and variability of the
psychological processes that occur during sleep, such as dreaming. Unfortunately, from the perspective of dream psychology, sleep researchers have focused
most of their attention on the biology of sleep-its physiology, pharmacology, and
chemistry-and have neglected the study of the dream. Nevertheless, whether
dreaming is stable or variable or both has considerable implication for our understanding of dreaming. If dreaming is not stable in some sense, then it is random
"noise" in the system, and of no scientific interest. Ifit is stable, then dreaming is
a regular process that can become the object of study and manipulation and thus is
of greater scientific interest. If, in addition, dreaming is variable in any sense, then
it takes on system characteristics of even greater interest because it is stable-flexible systems that are apt to participate in significant, i.e., adaptive, processes.
An exploration of the stability of dreaming explores its variability as well. As
has been done for sleep physiology (Moses et aI., 1972; Feinberg, 1974; Roth et
aI., 1977), an exploration of the stability- variability of dreaming would examine:
(1) the adequacy of dream measurement (reliability); (2) the level of overall dream
stability-variability (content means and standard deviations); (3) the trends in
stability across time (adaptation); and (4) the impact on the system of an acute
manipulation (first night and last night effects in the laboratory). Data from such a
study of dream variability-stability would allow a comparison of the psychology
of sleep (dreaming) with the physiology of sleep (sleep stages) from the same or
similar points of view.
Recognizing the potential value of an exploration of dream stability-variability
to both clinicians and researchers, we undertook to study the dream content of
subjects across a number of nights. It is essential, if we are to examine the
question of dream stability properly, to study enough normal subjects of the same
sex, age, and race for a sufficient number of nights in the sleep laboratory, without
any other manipulations, to obtain an adequate amount of data to be scored with a
reliable dream content measuring device. All of these factors are known to affect
dream content, have been discussed by us in other reports (Kramer et aI., 1975),
and are appropriately attended to in the design of our study.
METHOD
We studied 14 normal, white, male college student volunteers between the ages
of 20 and 25 for 20 consecutive nights in the sleep laboratory. The subjects reported to the sleep laboratory 1 hr before their normal bedtime. They were prepared for recording by having a central electroencephalographic lead, two electrooculographic leads, and one chin electromyographic lead affixed to their head
(Rechtschaffen and Kales, 1968). The subjects then went to bed and were
awakened from the end of each of the first four rapid eye movement periods
(REMPs) occurring each night to report on what they had been dreaming. The
subjects were allowed to sleep as long as they wished, but the night's sleep was
Sleep, Vol. I, No.3, 1979
STABILITY - VARIABILITY OF DREAMING
321
terminated if the subject entered the fifth REMP before he spontaneously chose to
end his night's sleep.
The dream reports were tape recorded, transcribed, and coded. They were
scored "blindly" and independently by two raters using the Hall- Van de Castle
dream content scoring system (Hall and Van de Castle, 1966) for three content
categories: characters, activities, and descriptive elements. The category of
characters is self-evident. Activities include such things as physical activities,
verbal activities, and movement. Descriptive elements include scoring for such
things as size, color, and intensity.
A score on each content scale for each subject on each night was derived by
summing across the dreams of each night for each subject. Means and standard
deviations for each scale were calculated for all 14 subjects over all 20 nights as
well as for weeks 1 and 2.
Pearson product moment correlations were done for each of the three content
categories for each successive night pair, transformed and then averaged across
the 20 nights. This correlation expressed the predictability of a given content level
from night to night. An overall mean correlation of three content category mean
correlations was also computed. The mean correlations for each of the three
content categories and a mean of the three correlations were computed for weeks
1 and 2. The correlations of nights 7 to 8 and 14 to 15 were not included to avoid
repetition in the former and expansion past 2 weeks in the case of the latter.
RESULTS
Recall
The study presents the possibility of collecting some 1,120 dreams (14 subjects
x 20 nights x four awakenings per night). Only 1,086 awakenings were made,
primarily because of missed first REMPs, i.e., subjects had only three REMPs
during some nights. Out of these 1,086 awakenings, 820 dreams were recalled for a
dream recall percentage of 76%.
Reliability
The two judges each scored all of the dreams on the three scales. The exact
percentage agreement dream by dream for each content category was for characters, 91%; activities, 93%; and descriptive elements, 89%. The overall percentage
agreement was 91 %.
Content
The means and standard deviations for the three content categories are as
follows: total characters, 7 ± 2; total activities, 14 ± 5; and total descriptive
elements, 6 ± 2. The means of the three content means and standard deviations
are 9 ±' 3.
The means and standard deviations for the three content categories for week 1
are as follows: total characters, 7 ± 5; total activities, 11 ± 12; and total descrip-
Sleep, Vol. 1, No.3, 1979
322
M. KRAMER AND T. ROTH
tive elements, 6 ± 6. For week 2, the means and standard deviations are as
follows: total characters, 6 ± 7; total activities, 12 ± 13; and total descriptive
elements,S ± 7. The averages of the three means and standard deviations for
weeks 1 and 2 are the same, 8 ± 8.
Correlations
The mean night to night correlations for each of the three content categories and
the mean of the three are as follows: total characters, 0.40; total activities, 0.51;
total descriptive elements, 0.45; and the average of the overall correlations, 0.46.
All the correlations but the one for total characters are significant (p ~ 0.05).
For week 1 the correlations were for total characters, 0.26; total activities, 0.25;
total descriptive elements, 0.14; and the mean of the three, 0.22. None of the
correlations for week 1 is significant.
For week 2, the night to night correlations were for total characters 0.45; total
activities, 0.56; total descriptive elements, 0.50; and the mean of the three, 0.50.
All four of these second week correlations are significant (p ~ 0.05). Although
they are all larger and significant, the week 2 correlations are not statistically
significantly different from week 1 correlations.
Acute Effects
The mean and standard deviations of the three content categories on each night
in the three night pairs are for nights 1 and 2, 8 ± 6 and 6 ± 6; for nights 10 and 11,
6 ± 7 and 10 ± 11; and for nights 19 and 20, 9 ± 12 and 8 ± 8.
The correlations for the three night pairs for each content category are in order,
i.e., 1-2, 10-11, 19-20, as follows: total characters, 0.45, 0.07, and 0.61; total
activities, 0.37, 0.48, and 0.94; and total descriptive elements, -0.05, 0.44, and
0.72. The mean correlation for each night pair across the three content categories
is for nights 1 and 2, 0.05; for nights 10 and 11, 0.30; and for nights 19 and 20, 0.80.
The mean night 19- 20 correlation across content categories is significantly different from the night 1-2 correlation (p < 0.02).
DISCUSSION
It is evident from even a cursory examination of the results of the present study
that the dream is sufficiently stable and variable to satisfy both the clinician and
the researcher. It seems worthwhile, however, to describe the implications of the
results for the clinician and the researcher and to contrast the present findings on
the stability of the psychology of sleep with the previous work on the stability of
the physiology of sleep.
The clinician finds support from the present results that the dream is stable
enough to reflect long range aspects of personality, e.g., an overall mean night to
night significant content correlation of 0.46, and yet variable enough to be potentially reflective of more immediate concerns of the dreamer, i.e., some 79% of the
night-to-night variance remains unexplained. Such results are congruent with an
increasing body of knowledge derived from experimental dream research that
Sleep, Vol, I, No.3, 1979
STABILITY-VARIABILITY OF DREAMING
323
suggests that dreams are indeed trait and state sensitive in normal and
psychopathological conditions (Kramer et aI., 1976a) and functionally related to
the waking affective state of the dreamer (Kramer et aI., 1976b; Roth et ai, 1976;
Kramer et aI., 1977).
The sleep researcher is interested in knowing if the dream can be reliably
measured, shows some degree of stability across time, does or does not adapt, and
whether it is responsive to manipulation. These basic questions can all be answered in a positive manner. Yet, the interest in dreams has been artistic rather
than scientific. Perhaps this is because the comparable results for the physiology
of sleep are so much more powerful. A comparison of the variability of sleep
physiology and sleep psychology might prove revealing.
First, can dreaming be adequately recovered for use? Clearly, we can obtain
dream reports in the laboratory at a rate of 76% of awakenings, which is adequate
for most purposes. Important psychological differences can be shown with material obtained at this rate, e.g., male-female (Winget et aI., 1972), sick-well
(Kramer et aI., 1969), young-old (Winget et aI., 1972), and schizophrenic-depressed (Kramer and Roth, 1973). Not all of these differences can be shown with
sleep physiology measures.
Second, can dreams be measured as reliably as sleep stages? It has been repeatedly demonstrated that dreams can be reliably measured, and this study simply confirms that fact (Hall and Van de Castle, 1966; Sandler et ai, 1968; Sandler et
aI., 1970; Reichers et aI., 1970). Our mean overall percentage agreement of91% is
certainly acceptable and comparable to sleep stage scoring reliability (Karacan et
aI., 1978).
Third, is dream content from night to night as stable as sleep stage physiology?
The overall sleep stage predictability night to night using percentage data is 0.44
and using the time data is 0.28 (Roth et aI., 1977).
We have two measures that address the question of the stability -variability of
dream content. The mean of the overall correlations of 0.46, which is statistically
significant, is the most direct expression of the stability of dream content. The
standard deviation of the mean of the overall content categories reflects the content variability. In 95% of cases, all content, i.e., characters, activities, and descriptive elements, will vary between 3 and 15 on any given night. This is a
reasonable and manageable range.
Dream content data are more like time than percentage data and yet the magnitude of the dream content data overall correlation is more like the latter than the
former. The stability of dream content across nights is clearly comparable to that
of sleep physiology. It has been suggested that the stability of dream content is a
function of its story-like nature and the fact that dreams are repeatedly filtered
through a recall process in which stable individual differences are known to occur.
Examining other story-like productions of the individual ,would help to specify
whether that apparent stability of dreaming is unique to the dream process or is a
function of other psychological processes of the individual.
Fourth, there has been a debate in the experimental dream literature about
whether dreams show evidence of adaptation across nights (Whitman et al., 1962;
Dement et aI., 1965; Hall, 1967; Piccione et aI., 1976). The present results are the
Sleep. Vol. I, No.3, 1979
324
M. KRAMER AND T. ROTH
first clear evidence we have found of adaptation. The week 2 correlations are larger
than those in week 1 in all three content categories and overall. None of the week 1
correlations is significant. while all of the week 2 correlations are significant.
Fifth and last, can a first night effect be seen in dream data as it has been
occasionally reported in sleep physiology studies? We would expect, because of
the so-called first night and last night effect, that content would be suppressed on
night 1 as compared to night 2 and likewise for night 20 as compared to night 19.
This was not the case. However, we did find that night 1 did not predict night 2 as
well as night 10 predicted night 11 or night 19 predicted night 20, suggesting a first
night effect. The answer here is equivocal. There may be a first night effect, but
whether this is apparent or not may depend on how it is measured.
We have examined the stability-variability of normal, unmanipulated dreaming. We conclude that it is both a stable and variable phenomenon that shows clear
evidence of adaptation across nights. We compared the results of dream stability
to those of sleep stage stability and found similar magnitudes. One may prefer to
study the psychology of sleep-the dream-or the physiology of sleep-sleep
stages-because of taste or interest but clearly not because one is art and the other
science.
REFERENCES
Dement W, Kahn E, and Roffwarg H. The influence of the laboratory situation on the dreams of the
experimental subject. J Nerv Ment Dis 140:119-131, 1965.
Feinberg I. Some observations on the reliability of REM variables. Psychophysiology 11:68-72, 1974.
Hall C. Representation of the laboratory setting in dreams. J Nerv Ment Dis 144: 198-206, 1967.
Hall C and Van de Castle R. The Content Analysis of Dreams. Appleton-Century-Crofts, New York,
1966.
Karacan I, Orr W, Roth T, Kramer M, Shurley J, Thornby J, Bingham S, and Salis P. Establishment
and implementation of standardized sleep laboratory data collection and scoring procedures.
Psychophysiology 15: 173-179, 1978.
Kramer M, Baldridge B, Whitman R, Ornstein P, and·Smith-P. An exploration of the manifest dream in
schizophrenic and depressed patients. Dis Nerv Syst (Supp\) 30: 126- 130, 1969.
Kramer M and Roth T. A comparison of dream content in dream reports of schizophrenic and depressive patient groups. Compr Psychiatry 14:325-329, 1973.
Kramer M, Winget C, and Roth T. Problems in the definition of the REM dream. In: Levin P and
Koella WP (Eds), Sleep 1974. Proceedings of Second European Congress on Sleep Research.
Karger, Basel, 1975, pp 149-156.
Kramer M, Hlasny R, Jacobs G, and Roth T. Do dreams have meaning? An empirical inquiry. Am J
Psychiatry 133:778-781, 1976a.
Kramer M, Roth T, and Palmer T. The psychological nature of the REM Dream. I. A comparison of
the REM dream report and T.A.T. stories. PsychiatrJ Univ Ottawa 1:128-135, 1976b.
Kramer M, Roth T, and Cisco J. The meaningfulness of dreams. In: Koella WP and Levin P (Eds),
Sleep 1976. Proceedings of Third European Congress on Sleep Research. Karger, Basel, 1977, pp
315-316.
Moses J, Lubin A, Naitoh P, and Johnson L. Reliability of sleep stages: Psychophysiology 9:78-82,
1972.
Piccione P, Thomas S, Roth T, and Kramer M. Incorporation of the laboratory situation in dreams.
Sleep Res 5:120,1976.
Rechtschaffen A and Kales A (Eds). A Manual of Standardized Terminology. Techniques and Scoring
System for Sleep Stages in Human Subjects. U.S. Public Health Service, U.S. Government Printing Office, Washington D.C., 1968.
Riechers M, Kramer M, and Trinder J. A replication of the Hall- Van de Castle character scale norms.
Psychophysiology 7:328, 1970.
Roth T, Kramer M, and Arand D. Dreams as a reflection of immediate psychological concern. Sleep
Res 5: 122, 1976.
Sleep. Vol. I. No.3. 1979
STABILITY - V ARIABILlTY OF DREAMING
325
Roth T, Kramer M, and Roehrs T. The consistency of sleep measures. In: Koella WP and Levin P
(Eds), Sleep 1976. Proceedings of Third European Congress on Sleep Research. Karger, Basel.
1977 pp 286-288.
Sandler L, Kramer M. Fishbein H. and Trinder J. Inter-laboratory reliability of the Hall-Van de
Castle character scale. Psychophysiology 6:248, 1968.
Sandler L. Kramer M, Trinder J, and Fishbein H. Inter-laboratory reliability of the Hall-Van de
Castle characters, social interactions, actiyities and emotions scale. Psychophysiology 7:333, 1970.
Whitman R, Pierce C, Maas J. and Baldridge B. The dreams of the experimental subject. J Nerv Ment
Dis 134:431-439, 1962.
Winget C. Kramer M, and Whitman R: Dreams and demography. Can Psychiatr Assoc J 17:203-208,
1972.
Sleep. Vol. 1. No.3. 1979