Relation of dreams to waking concerns
Introduction
Questions about the formation and function of dreaming have remained a matter of debate. Two hypotheses are tested here. One is that the formation of dreams is strongly influenced by the ongoing waking concerns of the sleeper. Recent work on the role of sleep in learning and memory has supported a “sequential hypothesis” (Giuditta et al., 2003). This states that mental activity does not stop at sleep onset but continues during slow wave sleep (SWS) when neuronal activation enhances salient and clears redundant features of information being processed. During rapid eye movement (REM) sleep this activation in turn stimulates associated memory networks which are experienced as dreams. The second hypothesis, known as the “mood regulatory function of dreaming” (Kramer, 1993, Indursky and Rotenberg, 1998), states that the effect of the SWS to REM sleep sequence is to down-regulate affect carried over from previous waking. This is accomplished by “contextualizing” the central affect in a metaphoric image and relating it to a network of previously stored images (Hartmann, 2002).
Dreams, then, are an intervening variable between waking emotional concerns and post-sleep mood. As such, they may become dysfunctional due to an overload of disturbed affect, or a failure to accomplish the linkage to past memories, which is essential to the reduction of disturbed mood (Cartwright, 2005).
This report is one of a series from a study investigating the contribution of REM sleep and dreaming to remission from an episode of untreated major depression, secondary to marital separation or divorce. It focuses on the reports from REM sleep, their degree and type of affect, relevance to the prior waking concerns of the dreamer and their linkage to older memory material.
Extensive research supports a correlation between marital discord and the onset of major depression. The Epidemiologic Catchment Area study reported a 25-fold increase in the relative risk of major depression for people in unhappy marriages (Regier et al., 1984, Weissman, 1987). Coryell et al. (1992) showed that marital discord is one of the primary risk factors for the onset of a first episode of depression. Kendler et al. (2002) outlined models of pathways leading to major depression. These authors also found that for the Adversity-Interpersonal Difficulties pathway, an additional risk factor for women before the onset of a current episode of major depression is the presence of “marital problems.”
There is also extensive research relating major depression to disturbances of sleep. Poor sleep efficiency, reduced SWS, a reduced latency to the first episode of REM sleep, and an irregular sequence of eye movement density from REM to REM, have all differentiated the sleep of the depressed from that of the non-depressed. (Kupfer, 1975, Gillin et al., 1979, Rush et al., 1982, Cartwright, 1983).
Given the recent work implicating the sequential collaboration of SWS and REM as necessary to continued information processing and improved waking performance (Smith, 2001, Ambrosini and Giuditta, 2001, Stickgold et al., 2001), the reduction in SWS and disturbances of REM sleep characteristic of depression might be expected to interfere with the continuity of information processing. Brain-imaging studies of depressed patients show increased activation of the limbic and paralimbic system in comparison to controls, suggesting that it is the emotional information processing that is disrupted in this disorder. Nofzinger et al. (2004) state that this heightened activation may be a response to an overload of affect arousal.
Dreams of depressed patients are also noted to be reduced both in quality and quantity. Studies have reported a high percentage of failure to recall any content from REM awakenings. Even when dreams are reported, there is poor elaboration of dream plots (Armitage et al., 1995) and bland or negative affect (Riemann et al., 1998, Cartwright, 1991).
As the degree of disturbance of sleep parameters, and the ability to form well-developed dreams co-varies with the severity of the depression, there will likely be variability in how well dreams display continuity in processing emotional information from waking into sleep, and consequent differences in the post-sleep effects on waking mood.
A previous study from this laboratory (Cartwright, 1991) compared the sleep and dreams in a sample of divorcing volunteers at two time points 1 year apart. Thirty-one of these subjects met major depression criteria at screening. Although none were treated for their depression, 22 (74%) were found to be in remission at the follow-up point. Those who were no longer depressed reported significantly more dreams in which the former spouse appeared as a dream character during their initial REM awakening night. This suggested that dreaming which includes a representation of an emotionally salient character may index an on-going adaptive process. Clearly this called for a replication study, one that would attempt to estimate the degree to which the subject experienced waking concern about the former partner, and the relative strength of this concern in comparison to other emotional issues. If this concern is high, it is predicted to continue into sleep and trigger the appearance of the spouse in the dreams that follow along with emotionally related images. Whether such dreaming contributes to mood regulation might depend on the nature of the older memory material to which it is linked. As divorce brings many life disruptions, such as relations to children, new financial burdens, loneliness, all of which extend over time, this event provides an opportunity for examining the continuity of affect-disturbing thought across the wake/sleep cycle and the role of dreaming in the re-equilibration of the internal emotional memory organization and its effect on subsequent waking mood.
Section snippets
Methods
An earlier article described the sample design and instruments for this study (Cartwright et al., 2003). The design will be summarized briefly here (see Table 1). This study is longitudinal, lasting 5 months with three daytime assessment points (at Screening, Month 3 and Month 5) and three sleep laboratory studies (at Months 1, 2 and 4). Each sleep laboratory study consisted of two consecutive nights of monitored sleep, following an initial clinical night to rule out those with a sleep disorder
Results
There were eight items on the Current Concerns test that received significantly higher scores from the Depressed than the Control group at the first month (see Table 2). Three of the four items with the highest mean concern for the Depressed group relate to the loss of the marriage partner. Differences between the three groups Remitted (R), Not Remitted (NR) and Controls (C) on the CC test were tested by one-way ANOVA with post hoc multiple comparisons using the Bronferroni correction on the
Discussion
This study tested two hypotheses that the formation of dreams is related to ongoing emotional concerns of the dreamer and that one function of dreaming is affect regulation. One difference between the dreams of those depressed subjects who were in remission at the conclusion of the study from those who were not was not as predicted. The NR group did not fail to continue their waking concern about the former partner into sleep, but did fail to experience emotion in these dreams, and to imbed the
Acknowledgments
This study was supported by a grant to the first author from the National Institute of Mental Health (MH-50471).
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- 1
Present address: Yuzuncu Yil University, School of Medicine, Van, Turkey.
- 2
Present address: Northwestern University, Medical Center, Chicago, IL, USA.