Factors
Affecting the Continuity between Waking and Dreaming
Michael Schredl, PhD,
works at the Sleep Laboratory, Central Institute of Mental Health,
Mannheim, Germany. He has worked in the field of dream research
since 1990, has published many articles and has served on the IASD
Board of Directors.
Abstract
Many researchers are advocating
the so-called “continuity hypothesis” of dreaming which simply
states that dreams reflect waking-life. For deriving specific
hypotheses, Schredl (2003) formulated a mathematical model that
specifies factors that affect the probability that certain
waking-life experiences are incorporated into subsequent dreams.
One of them is emotional involvement associated with the
waking-life experience.
The
present study applying a diary approach is directly linking
parameters of emotional involvement to the incorporation rate into
dreams.
Method
The sample included 46 psychology
students whose mean age was 20.7 years (SD = 2.8). There were 40
women and 6 men. Each participant kept a structured diary over a
two-week period. Every evening, they were asked to list the five
most important events of the day and rate them along a five-point
scale measuring emotional tone (-2 = very negative, -1 = slightly
negative 0 = neutral, 1 = slightly positive, 2 = very positive)
and a four-point scale measuring emotional intensity (being
affected by the event: 0 = not at all, 1 = small effect, 2 =
strong effect, 3 = very strong effect). These scales were of a
Likert-type format. On the following mornings, dream recall was
rated. In addition to the recording of their dream(s) as
completely as possible, participants were instructed to state
whether events of previous days occurred in the dream (including a
brief description of these events). If an event was listed on the
previous pages eliciting the five most important events of the
day, the participants should record the number of the
corresponding sheet and event.
Results and Discussion
The findings of the present study
indicate that emotional intensity of a daytime event rated by the
person heightened the probability of this event being incorporated
into subsequent dreams (Incorporated experiences: 1.68 ± 0.83 vs.
not incorporated events: 1.44 ± 0.48; effect size = 0.26, t = 2.1,
p = .0210, N = 64 events, N = 31 participants, mixed model). A
similar effect for emotional tone has not been observed
(Incorporated events: 0.39 ± 1.33 vs. not incorporated events:
0.29 ± 0.55; effect size = 0.07; t = 0.6, p = .5684, N = 62
events, N = 31 participants; mixed model).
The
study clearly demonstrated an effect of emotional intensity on the
incorporation rate of waking-life events into dreams and thus
corroborates that one of the factors of the model formulated by
Schredl (2003) is of importance. It seems it will be very
promising to design studies that investigate all factors of the
model – preferably simultaneously – with different methodological
paradigms (diary studies eliciting effect of everyday events on
dreams, laboratory studies applying experimental manipulation of
what is experienced during the day) in order to arrive at a
comprehensive, empirically tested, and precise formulation of the
continuity hypothesis.
References
Schredl, M. (2003). Continuity
between waking and dreaming: A proposal for a mathematical model.
Sleep and Hypnosis, 5, 38-52.
