Dreaming, Vol. 13 No. 4, December, 2003


Personal Problem-Solving Using Dream Incubation: Dreaming,

Relaxation, or Waking Cognition?

Gregory L. White1,3 and Laurel Taytroe2


In Experiment 1, 96 frequent dreamers were randomly assigned to Control or Experimental conditions. All participants rated waking and dream moods over ten days and recorded their most vivid dream for each night. On the first and tenth day they rated the levels of distress and solvability of up to eight specific personal problems. After ten days they also rated degree of improvement and problem-solving effort for each nominated problem. All Experimental participants also cognitively reviewed one particular focal problem each day. Experimental participants were also randomly assigned to use either a dream incubation technique (Delaney, 1996) for this focal problem either just before sleep or just after morning wakening, or to use a simple relaxation technique either just before sleep or just after wakening. Night dream incubation participants were particularly likely to report reduced problem distress, greater problem solvability, and improvement in their focal problem. Daytime anxious and depressed moods of the night dream incubation participants decreased over ten days relative to Controls. In Experiment 2 participants predicted how they would have been affected by either night or morning incubation instructions used in Experiment 1. Results did not support an expectancy interpretation of Experiment 1.

KEY WORDS: dream incubation; problem-solving.


Dream incubation refers to a variety of techniques that supposedly aid practical problem-solving or creativity. Dream incubation has an ancient history as well as modern use (Barrett, 2001; Blagrove, 1993, 1996; Bulkeley, 2000; Delaney, 1996; Dement, 1999; Flowers, 1995; Hartmann, 1998; Krippner, 1981; Reed, 1976; Saredi, Baylor, Meier, & Struach, 1997; Strunz, 1994; Van de Castle, 1994). Incubation techniques share a common feature of some method of focusing attention on a particular problem prior to sleep in the expectation that cognitive or affective dream processes might then be engaged in a way that assists problem resolution. Hill (1996), for example, reviewed research indicating that focusing on dreams is helpful in preparing clients for psychotherapy. Barrett (2001) presents a wealth of mostly case material from a variety of artistic and scientific fields that suggests dreams might be useful in creative problem-solving.

There has been little research that demonstrates that an incubation technique leads to problem-solving creativity or problem-resolution. Barrett (1993) asked college students to incubate a specific "problem of personal relevance with recognizable solution(s)" (most chose "problems of a personal nature") using Dement’s incubation method of thinking about the problem for fifteen minutes prior to sleep (1974, reported in Dement, 1999, p. 321). Participants recorded their dreams for a week and indicated which ones they thought addressed "any aspect of the problem or attempted any solution of it." Of those dreams, participants then indicated the ones they "believed contained a satisfactory solution." In addition, two judges also rated the dream reports on both criteria and achieved substantial agreement both with each other and with the participants’ ratings. Participants rated 49% of their dreams as relevant and 34% of them as containing a solution while judges corresponding ratings were 51% and 25%. Judges’ choices of solution-containing dreams were more literal and less metaphorical than were participants’ choices. Barrett’s method did not allow for assessment of the relationship between the dream solutions and more objective measures of eventual problem outcomes. Saredi et al. (1997) also report that for a small sample of participants in a sleep laboratory study, thinking of a question related to a current problem prior to sleep increased the likelihood that dream content reflected the problem, but that this effect was weakened when dream length was controlled for.

Cartwright (1974) used a complicated design in which participants were presented with three different types of problems: crossword puzzles, the Remote Associates Test (RAT), and Thematic Apperception Test (TAT) pictures. Participants slept in a sleep laboratory; a different problem type was chosen for each night. Problem-solving outcome was assessed after either an interval of wake or an interval of sleep and compared to baseline measures of problem-solving outcomes taken prior to sleep. There was no specific incubation technique used, but participants worked on similar problems for a baseline period before sleep which is similar to Barrett’s use of Dement’s "thinking about" incubation technique. Results indicated that compared to baseline, participants wrote more successful outcomes for TAT pictures after a period of REM sleep than after a period of wakefulness. There was no effect on puzzle or RAT measures. Cartwright offered several explanations for this finding, including the possibility that for "problems of an emotional nature" dreaming provided "additional associations . . . and possibilities previously unattended making them more available for later conscious consideration" Cartwright, 1974).

Domhoff notes several problems with the problem-solving paradigm of dream function, including the possibility that studies like Barrett’s and Cartwright’s and others not reviewed here (e.g. Saredi et al., 1997) fail to separate the effects of waking thought (as well as nondreaming "thought" which can occur during sleep) about the problem from putative dream processes (2003, pp. 158-159). Blagrove (1993, 1996) suggested that dream cognition does not have reflexive and intentional components necessary for problem-solving. Since waking cognition can affect dream content, correlations between dream content and problem improvement may reflect waking cognition rather than a causal effect of dream processes. Both Domhoff (2003) and Blagrove (1993, 1996) note that waking reflection on the meaning of a dream that yields insight or direction into problem-solving is not evidence that dream processes account for the insight but rather may merely reflect waking cognitive processes.

Hence, interpretation of previous incubation research is problematic. The main impetus for Experiment 1 was to provide a more substantial test of the hypothesis that dream incubation might lead to better problem outcomes. In order to provide a better test than previous literature it would be important to take into account waking cognitive activity, possible expectancy effects, and the relaxation component of incubation methods. The problem of waking cognition has been mentioned above. In Experiment 1, all experimental participants followed a structured cognitive problem-solving procedure while control participants did not do so. Hence comparisons among experimental conditions were expected to show the effects of incubation instructions beyond the effects of waking attention; comparisons of incubation vs. non-incubation conditions to controls could similarly show effects of incubation plus waking cognition relative to controls. As another means of assessing the effect of dream processes vs. waking cognition, in Experiment 1 some participants were randomly assigned to practice an incubation technique just prior to sleep while others were assigned to practice the technique just after wakening. It was expected that if dream processes are actually involved, then at a minimum the night incubation participants should show improved problem outcomes relative to day incubation participants. There is some previous research that suggests, however, that day incubation techniques could improve problem-solving, but these techniques clearly do not induce dreams during the day (Houtz & Frankel, 1992).

Another problem is that a dream incubation technique may induce relaxation. There is substantial evidence that relaxation training can improve psychotherapy outcomes and personal problem-solving (Lehrer & Woolfolk, 1993; Lehrer, Carr, Sagunaraj, & Woolfolk, 1993). It is possible that dream incubation techniques might be effective if they produce greater relaxation, regardless of their impact on dream content or process. In order to rule out this possible interpretation of incubation effects, in Experiment 1 some participants were randomly assigned to a dream incubation technique while others were assigned to a relaxation technique.

It is also possible that participant’s expectations about the usefulness of dreams in problem-solving may lead to improved problem-solving independently from any dream process. Positive expectations might decrease anxiety about the problem because of greater hope, and perhaps like a relaxation component, decreased anxiety could lead to improved problem-solving either through attentional or reflexive cognitive processes (Blagrove, 1996; Olson, Roese, & Zanna, 1996; Snyder, Michael, & Cheavens, 1999). Experiment 2 was conducted to provide evidence about the likelihood that such expectancy effects could account for the results of Experiment 1.

Finally, several theorists within the problem-solving paradigm have noted that dream processes may be most likely engaged to solve emotionally relevant problems as opposed to abstract puzzles used in some research designs (Barrett, 1993; Cartwright 1996; Dement, 1999, pp. 320-322; Domhoff, 2003 pp. 158-167; Hartmann, 1998, pp. 151-153; Revonsuo, 2000; Schatzman, 1984). Accordingly, it may be expected that dream incubation techniques are more likely to produce improved problem-solving for emotionally relevant problems. Further, if dreams function to solve problems, then problems that seem insoluble may not successfully engage dream resolution and incubation of such problems might lead to waking or dream distress (cf. Hartmann’s discussion of posttraumatic dreams and nightmares, Hartmann, 1998). Experiment 1 used a procedure by which participants nominated a specific current problem that they believed was potentially solvable by their own efforts within the time frame of the study.

Based on the above considerations, we expected that if dream incubation engages dream processes that might lead to better problem-solving, then we would expect that participants who practiced a dream incubation technique just prior to sleep should report improvement in the problem that is the focus of the dream incubation, should be less distressed about the problem, and should report the problem as more solvable compared to participants who merely relaxed, to participants that practiced the incubation technique in the morning, and to controls who were not actively focused on problem-solving. Further, this night incubation effect should improve problem outcomes beyond any effects of waking cognition directed towards problem resolution.



The experimental design consisted of a 2 x 2 between subjects design plus a control condition with random assignment to all conditions.


100 undergraduate and graduate students originally volunteered for an experiment on "dreaming" that was open only to "frequent" dreamers. Course credit was not given. Frequent dreamers were recruited in order to increase the number of recalled dreams available for analysis and because research has generally indicated that dream frequency is not strongly related to personality traits, especially when gender effects are partialled out (Blagrove & Akehurst, 2000; Domhoff, 2003, pp. 158-159; Schredl & Montasser, 1996; Strauch & Meier,1992; Wolcott & Strapp, 2002). Data from four participants were discarded due to failure to follow directions, leaving 96 participants, 19 males and 77 females.


Each participant was given a research booklet containing pre and post participation Problem Surveys. Between these two surveys were ten identical sections, one for each day of participation. Each section first had a daily rating of moods, then a cognitive review form and instructions, then the experimental instructions for the condition the participant had been assigned to, then a dream record, and finally a dream moods measure. However, participants in the Control condition did not receive cognitive review forms or instructions or experimental instructions.

Problem Surveys and Measures of Problem Solvability, Problem Distress, Problem Improvement, and Problem Effort

At the beginning and end of the booklet were two problem surveys, pre- and post-participation, which instructed participants to "write down problems for which you are currently moderately distressed. In addition, the problem should seem to be potentially solvable at least in part through your efforts, that requires some action or deliberation on your part in order to be solved." Eight categories of potential problems were listed: Interpersonal Problems (not of a sexual nature), Academic Performance, Financial Difficulties, Problem with Parents, Problem with Health, Problem with Academic Direction, Problem with Physical Appearance, and Moral Dilemma. Two examples were provided for each category. Participants wrote specific problems, if they had them, in the booklet, and then rated on 7-pt. scales the extent to which the problem was "probably unsolvable" to "probably solvable" and "mildly distressing" to "very distressing." The post-participation survey asked participants to again write in the specific problem in each category they had originally indicated on the pre-participation survey, and then to rate problem solvability and distress based on their "current feelings and opinion, which may or may not be different from what you indicated earlier." In addition, on the post-participation survey each problem was rated on the extent to which "the problem has become" "much worse" to "much better" using a 12-pt. scale. Participants also rated "how much effort have you put into solving the problem" over the participation period using a 7-pt. scale with endpoints labeled "little effort" to "great effort."

Daily Mood

Daytime moods were assessed by the Profile of Mood States (POMS) (McNair, Lorr, & Droppleman, 1992), a 65-item questionnaire widely used in research, including dream research (e.g., Cartwright, Luten, Young, Mercer, & Bears, 1998) to measure mood. Items are summed to yield six emotion factor scores of Anxiety, Depression, Anger, Vigor, Fatigue, and Confusion. Participants were instructed to rate "How you have been feeling today considering all that has occurred throughout the day." Participants were instructed to complete the POMS "each night before you go to sleep."

Dream Record, Dream Moods, and Dream Frequency

Ten 1.5 page blank dream records were provided, each preceded with instructions used by Domhoff (1999). Participants were directed to "write down the one that is most memorable and vivid" if they recalled more than one dream on any particular morning. They were also instructed to record their dreams "as soon as you wake up—before continuing your morning routine." If they recorded a dream on a particular day, participants were instructed to rate "How you felt in your dream" using the 65 items of the POMS.

Dream frequency is the number of dreams the participant recorded over the 10 days of the study and hence could range from 0 to 10 dreams. Unfortunately, these dream records have not been content analyzed due to lack of resources to transcribe and analyze them.

Cognitive Problem Review

Control participants were not instructed in any way to review their problems. Participants in the four experimental conditions were presented with ten identical cognitive review forms that were labeled "data sheet." For each day of participation, participants were asked to "take no less than five minutes and no longer than ten minutes to think about questions on the data sheet," to write down again their specific personal problem of focus, to "briefly review what you did (in the preceding day) and jot down a list of the major activities, events, feelings, or experiences," and to "think of the personal problem that is your focus during this study. Ask yourself if you are ready yet to do something about it. Take two minutes to review quickly as many aspects of the problem as you can." They were then instructed to write down, in spaces provided, separate responses to the following questions: "What do you now think are the causes of the problem?," "What are some solutions? Why won’t one of them do?," "What resources or information do you know think you need to help you solve this problem?," "What might you gain if this problem were solved? What might you lose if this problem were solved? What might you gain if this problem were not solved?," and "How would things be different for you and others if the problem were resolved?" These questions are modifications of a process suggested by Delaney (1996, pp. 27-34) prior to use of her specific dream incubation technique. They also correspond to typical cognitive problem-solving activities that Blagrove (1992, 1996) has suggested may account for dream incubation effects.


Participants were instructed individually or in groups of 2 or 3 if they were assigned to the same condition. Participants were assured anonymity of their responses and assigned a code to use rather than their names when responding to questionnaires. The researcher did not discuss the purposes of the study, but did provide a means for participants to find out the purposes of the study after their participation was over. Specifically, they did not tell participants that the study was concerned with the effect of dream incubation techniques on the content or frequency of dreams.

The researcher then reviewed each section of the research booklet step by step with the participant and emphasized that participation required filling out ten days’ worth of questionnaires over a maximum 12-day period. The researcher also read out loud all printed instructions relevant to the independent variables, and emphasized to participants in the four experimental conditions that they were to choose one of eight possible problems for their focal problem, using the same problem on each of the ten days of their participation. Participants then filled out the pre-participation Problems Survey. Without looking at these surveys, when participants finished the researcher again read the instructions concerning the Problems Survey and confirmed with each participant that they had followed the procedure.

Participants assigned to one of the four experimental participants then chose one of up to eight specific personal problems they had listed on the Problems Survey as a focus for cognitive review and, in the Incubation conditions, as a focus for the incubation technique as well. The only restriction was that the problem they chose had to be "moderately solvable" and "moderately distressing". This restriction was done to minimize ceiling and floor effects and to produce a focal problem with some possibility of improvement over the period of the study. To insure compliance with instructions, participants were asked to write their focal problem in a space provided on each of the 10 cognitive review sheets in their research booklet. 47 experimental participants (62.8%) chose an interpersonal problem as their nominated problem of focus, 19 (24.4%) nominated an academic problem, while the remaining 12 (12.8%) participants chose a financial, health, academic direction, or physical appearance problem (ns = 4, 3, 2, 3). No participant chose a parental problem or a moral dilemma as a focal problem. There were no differences among experimental conditions in likelihood of nomination of an interpersonal or academic problem, X 2 (3, N = 78) = 3.91, ns.

Control participants did not choose a focal problem. However, for purposes of data analysis, it was necessary to contrast night-incubation (NI, see below) and control conditions on measures concerning focal problem distress, solvability, improvement, and effort. To make these comparisons it is desirable that the NI participants’ focal problems were the same problems as those being rated by the control participants. Two methods, yoked and averaging, were used to conduct these contrasts, both yielded essentially similar results. The results of the yoked method are presented here. For the yoked method, it was noted that for the 22 participants in the NI condition, 13 chose an interpersonal problem and 5 chose an academic problem. The 18 control participants were then yoked to the NI participants by randomly choosing 13 interpersonal problems and 5 academic problems of the control subjects as the "focal" comparison problem (though control participants had not nominated a focal problem), with the constraint that the control subject had in fact listed a specific interpersonal or academic problem on their initial Problem Survey. This yoked method was repeated three times and each time the statistical results revealed the same patterns of significance. For the averaging method, not reported here, the mean of all specific problems listed by each control participant was used as the focal comparison problem for contrasts between NI and control conditions.

For 10 days over a period of 12 days all control and experimental participants rated their daily moods, recorded their most vivid dream, and rated their dream moods after recording any dream. Participants in the experimental conditions were given written instructions in the research booklet to do a cognitive review of their focal problem after recording their daily moods. At the end of their participation period they completed the final Problems Survey.

Experimental Instructions

Participants assigned to the four experimental conditions were directed both by the researcher and by written instructions in the research booklet to use the incubation technique just prior to sleep (Night Incubation—NI), to use the incubation technique soon after waking up (Day Incubation—DI), to use the relaxation technique just prior to sleep (Night Relaxation—NR), or to use the relaxation technique soon after waking (Day Relaxation—DR). Note that participants assigned to the two Day conditions still conducted their cognitive problem reviews in the evening before going to sleep.

For participants assigned to experimental conditions, experimental instructions were repeated following each of the ten structured cognitive problem review forms. This insured that for all 10 days of participation, participants would be explicitly reminded of their experimental instructions immediately after each daily cognitive review.

Incubation Instructions

Delaney (1996) reported in detail the method of dream incubation she has used in counseling settings for many years. While there are no experimental studies validating this specific technique, it was chosen as the incubation technique since it is relatively well known, has been used in counseling settings, and was relatively easy to translate into an experimental research paradigm. Participants assigned to the Incubation condition were directed to follow instructions modified from Delaney (1996, pp. 31-32) either "15 minutes before going to sleep" (NI) or "15 minutes after waking up" (DI):

Write down a one-line question, phrase, or request that expresses something you think is important for you to know or do in order to help you solve your personal problem. It is not a wish that something would happen to another person or to circumstances beyond your control that are part of your focus problem. Examples are: "Help me understand my friend _____," "What is really going on between _____ and me?," "Give me an idea for my physics project," "How can I get motivated to do _____?," and "How can I improve my study habits?" You might think of several phrases before you find one that seems most direct and appropriate. Be as specific as you can to your focus problem. You may or may not decide to use the same phrase as you used on a previous night but, if you are using the same phrase, still write it down on this sheet.

Participants were then instructed to write down their question, phrase or request in the research booklet, and the instructions continued:

Repeat this phrase to yourself quietly over and over again for five to ten minutes at the same steady rate. If you start thinking about something else as you are saying this phrase, as soon as you notice that your mind has wandered merely start repeating the phrase again. While you are repeating the phrase, bring your attention to focus on it. Make an effort to really pay attention to your phrase as you are repeating it. Keep repeating this phrase for no less than five minutes and no longer than ten minutes, then stop.

Relaxation Instructions

Participants assigned to the Relaxation condition were directed to follow instructions similar to those used in research on meditation and relaxation (Lehrer & Woolfolk, 1993) either "15 minutes before going to sleep" (NR) or "15 minutes after waking up" (DR):

Now, turn off the lights in your bedroom, lie down, and let yourself fall asleep. While you are falling asleep, repeat the phrase "Relax" over and over again at the same steady rate. If you start thinking about something else as you are saying "Relax," as soon as you notice that your mind has wandered merely start repeating the word "Relax" again. While you are repeating the word "Relax," bring your attention to focus on it. Make an effort to really pay attention to the word as you are repeating it. Keep repeating "Relax" until you fall asleep. If you have not fallen asleep within ten minutes, then stop repeating the word and let yourself fall asleep.


Dream Frequency

There were no differences in reported dream frequency among the five experimental conditions (F (4, 91) = 3.60, ns). Overall, participants reported a mean 5.92 (S.D. = 2.65) dreams over the ten day period of the study. The actual number of recalled dreams was probably larger as participants were instructed to record only the most memorable and vivid dream each morning.

Dream Content

As mentioned earlier, a content analysis has not been performed on the dream records due to lack of resources. Previous research indicates that occasionally a problem-solver may have a dream which is manifestly related to a problem solution, or which has been interpreted by the dreamer as related to a problem (Barrett, 2001; Delaney, 1996; Hill, 1996; Van de Castle, 1994). A non-blind review was conducted of the reported dreams for explicit, specific commentary in the dream record that the dream was either about the focal problem or had provided a specific solution to the focal problem. (Unlike Barrett (1993), participants were not explicitly asked to indicate if their dreams were related to their focal problem.) There were few such spontaneous comments in the dream records, and they were equally likely to be reported in all of the experimental conditions.

Gender differences

Gender differences were assessed for all variables by independent t tests. The number of significant tests was less than 5%, or chance levels, of all tests. Since males were only 19.8% of the sample, tests for interactions of gender with experimental variables lack in power and were therefore not explored.

Correlations Among Problem Solvability, Distress, Effort, and Improvement Measures

As might be expected, pre and post solvability and pre and post distress scores were correlated (rs = .48, .32, ps < .05). Pre solvability and distress were not correlated with improvement ratings, rs = .12, .03, while post solvability and distress were correlated with improvement in expected directions, rs = .39, -.61, ps < .05. Effort was significantly correlated both with post solvability and improvement, rs = .39, .31, ps < .05. No other correlations among problem measures reached significance.

Dream Frequency Correlations with Problem Measures and Moods

There were no significant correlations between reported dream frequency and ratings of distress, solvability, effort, or improvement. Dream frequency was positively correlated with dream anxiety, dream depression, dream anger, dream vigor, and dream fatigue (Ns = 96, rs = .57, .39, .36, .57, and .31, all ps < .01.) Frequency was negatively correlated with day fatigue, r = -.23, p < .025) but was uncorrelated with any other daytime mood.

Effects of Experimental Variables on Problem Measures

Table 1 presents the mean scores and their standard deviations for the four Experimental conditions and the Control condition for pre and post solvability and distress scores and for improvement and effort scores. The data analytic procedure was to conduct a 2 x 2 x 2 ANOVA on solvability and distress scores assessing the effect of incubation/relaxation, day/night, and pre/post factors. If the predicted three-way interaction reached significance, contrasts were conducted on post solvability and distress scores contrasting the NI vs. the NR, DI, and DR conditions. A priori contrasts between scores in the NI and Control conditions were also conducted. A 2 x 2 ANOVA was also performed on improvement and effort scores assessing the effect of incubation/relaxation and day/night instructions.


The analysis yielded two significant effects for pre/post and incubation/relaxation (Fs (1, 74) = 8.48, p < .005, and = 6.15, p < .025). Problems were judged as more solvable at the end of the experimental period rather than at the beginning, Ms = 5.56, 5.08 and solvability in the incubation condition was rated higher than in the relaxation condition, Ms = 5.70, 4.97). These are qualified by the expected interaction of incubation/relaxation, day/night, and pre/post (F (1, 74) = 3.79, p < .05). Examination of the means in Table 1 suggests that solvability increased the most in the night/incubation condition compared to the other three conditions (mean increases of 1.09 for NI vs. .024 for NR, .06 for DI, and .43 for DR). Planned contrasts indicated that post solvability was greater in the NI condition compared to the other three experimental conditions (t (74) = 2.10, p < .05). Planned comparisons between NI and yoked Control conditions indicated no difference in pre solvability (Ms = 5.13, 4.61; t (38) = .33, ns) while yielding a significant difference in post solvability (Ms = 6.23, 4.78; t (38) = 3.73, p < .001).


Analyses yielded a main effect of pre/post (F (1, 74) = 9.54, p < .005, with less distress reported at the end of the study (Ms = 4.91, 4.31). There were also significant interactions of incubation/relaxation with pre/post and with day/night (Fs (1, 74) = 7.56, 10.52, ps < .01, .025). These two-way interactions are qualified by the expected significant interaction of pre/post, incubation/relaxation, and day/night (F (1, 74) = 4.54, p < .05). Examination of the means in Table 1 suggests that distress decreased the most in the night/incubation condition compared to the other three conditions (mean decreases of 1.93 for NI vs. .11 for NR, .25 for DI, and -.13 for DR). Planned contrasts indicated that post distress was less in the NI condition compared to the other three experimental conditions (t (74) = 3.32, p < .001). Planned comparisons between NI and yoked Control conditions indicated no difference in pre distress (Ms = 5.41, 5.11; t (38) = .90) while yielding a significant difference in post distress (Ms = 3.48, 4.78; t (38) = 2.85, p < .01).

Problem Improvement.

More improvement was reported in the incubation than the relaxation conditions (Ms = 8.42, 6.95; F (1, 74) = 6.06, p < .025). There was a near significant effect of day/night, with more improvement reported in the night than the day condition (Ms = 8.02, 7.19, F (1, 74) = 3.50, p < .075). Again, these are qualified by the expected interaction of day/night and incubation/relaxation F (1, 74) = 4.97, p < .05. Planned contrasts indicated that improvement was greater in the NI condition compared to the other three experimental conditions (t (74) = 4.00, p < .001). Improvement was also greater for the NI condition than for the Control condition (Ms = 9.32, 6.33, t (38) = 4.48, p < .001).


There were no significant effects found in the ANOVA. However, the interaction of day/night and incubation/relaxation was near significant (F (1, 74) = 2.88, p < .10). Post-hoc range and multiple comparison tests indicated no significant differences among means for the four experimental conditions. Effort was no greater for the NI condition than for the Control condition (Ms = 5.50, 5.00, t (38) = 1.09, ns).

Comparison of Night Incubation and Control Conditions on Mood Measures

Because the analyses of the problem measures supported the predictions of the efficacy of the NI condition vs. all other conditions, and because significant interactions with no consistent patterns were found for mood data for the Experimental conditions, mood analyses were conducted just comparing the NI and control conditions. Each of the six POMS mood measures (Anxiety, Depression, Anger, Vigor, Fatigue, and Confusion) was submitted to a 2 x 10 ANOVA crossing NI/Control with Time (ten days). Analyses were conducted separately for day moods and dream moods.


Both day and dream anxiety decreased over time. A main effect of Time was found for day anxiety (F (9, 342) = 2.05, p < .05), and the linear trend for this effect was significant (F (1, 38) = 13.583, p < .001). There was a near significant effect of Time for dream anxiety, (F (9, 342) = 1.68, p < .10), and the linear trend for this effect was significant (F (1, 38) = 19.430, p < .001). However, NI/Control interacted with Time for day anxiety (F (9, 342) = 3.01, p < .005). There was no effect of Time on control day anxiety, while the effect of Time on NI day anxiety was significant (F (9, 189) = 4.85, p < .001) and linear (F (1, 22) = 31.38, p < .001). NI/Control and Time did not interact to affect dream anxiety scores. Day and dream anxiety were positively correlated, r = .29, p < .005.


There was a trend for the effect of Time on day depression (F (9, 342) = 1.72, p < .10), and this trend had a linear component (F (1, 38) = 6.59, p < .025). The interaction of Time and NI/control was not significant (F (9, 342) = 1.48, p < .15). However, the effect of Time on NI day depression also showed a trend (F (9, 342 = 1.72, p < .10) and this trend also had a significant linear component (F (1, 38) = 6.59, p < .01) while for control day depression there was no significant effect of Time or of any trend. There were no effects on dream depression. Day and dream depressed mood were also correlated, r = .33, p < .001.


There was no effect of Time, NI/control, or their interaction on either day or dream anger.


Day vigor was higher in the NI condition than the Control condition, Ms = 14.19, 8.9, F (1, 38) = 5.87, p < .025. Dream vigor and was nearly significantly higher in the NI condition as well, Ms = 6.66, 5.02, F (1, 38) = 2.68, p < .11. There were no trends, linear or otherwise, associated with these effects.


Day fatigue decreased over time, F (9, 342) = 4.22, p < .001, and this decrease was linear, F (1, 38) = 17.18, p < .001. There were no other effects on either day or dream fatigue.


Both day confusion and dream confusion decreased over time, Fs (9, 342) = 1.84, 2.21, ps < .06, .025. Both trends are linear, Fs (1, 38) = 4.40, 5.52, ps < .05, .025. There were no other effects on either day or dream confusion.

Discussion of Experiment 1

The results support the contention that dream incubation techniques can lead to reported improvements in personal problems and moods. Relative to other experimental conditions and to controls, participants in the night incubation condition reported that their focal problem had become more solvable, that it had improved, and that they were less distressed by it. Further, the night incubation condition produced a linear decrease in anxious and depressed moods over a ten-day period of nightly use of the incubation technique, relative to the control condition.

The results are particularly useful in that some possible confounding factors were controlled or limited by the experimental design. Since all experimental subjects engaged in the same cognitive review of their focal problem, the observed interaction effects cannot be explained by differential engagement of waking cognitive problem-solving in different conditions (Blagrove, 1996; Domhoff, 2003). The failure of relaxation instructions to produce problem improvement weakens the argument that the incubation technique merely produced greater relaxation thereby reducing unpleasant moods that could otherwise impair problem resolution. The pattern of results supports the contention that it is something about the dream process itself than can lead to problem improvement.

One alternative explanation for these results is that participants in the night incubation condition may have expended greater effort to solve the problem independent of dream process, and that the greater effort could account for reported problem improvement. However, although effort was correlated with post-participation solvability and improvement scores, there were no differences among experimental conditions in reported effort to improve the focal problem and also no difference between night incubation and control conditions in effort ratings. Likewise, the night incubation effect cannot be explained by variables related to dream frequency, as there were no differences among experimental and control conditions in dream frequency.

Another alternative explanation for the results is that participants’ belief in dream problem-solving efficacy reduced anxiety that was interfering with solving the focal problem, leading to improvement. The night incubation condition may be the condition in which belief in dream efficacy was most likely activated as it is most consistent with a belief that dreams can solve problems. Even though participants were not told anything about the purposes of the study, if they believed that an incubation technique followed by sleep would be helpful in solving problems, then their mood might improve regardless of any mediating role of dream process. Experiment 2 was conducted to assess the possibility that expectancy effects could have produced the pattern of data reported in Experiment 1.




A sample of 30 undergraduate and graduate students volunteered for an experiment on "dreaming" that was open only to "frequent" dreamers; this was the same recruitment announcement as used for Experiment 1. Course credit again was not given.


Participants reviewed the instructions given to all participants in Study 1, including those for collection of data over ten days, the exact instructions for cognitive review, personal problem rating and selection, and instructions for the incubation technique.


Half of the participants were randomly assigned to review the instructions for the Night Incubation condition and the other half reviewed the Day Incubation condition instructions. All subjects were then asked carefully read the instructions and to imagine that they were an actual participant in the study they reviewed.


Participants were asked to respond to the following questions concerning their expectations of how they would have reacted if they had been a participant in Experiment 1: Solvability of their personal problem after ten days, level of distress due to the problem after ten days, whether their problem would have improved or become worse over ten days using the incubation technique (12 pt. scale with endpoints labeled "Much worse" and "Much better"), level of effort they would put into solving the focal problem, how personally useful the incubation technique would be in solving a personal problem, and how useful to people in general the incubation technique would be in solving a personal problem (these last two questions used a 7 pt. scale with endpoints labeled "Not at all helpful" and "Very helpful"). Solvability, distress and effort questions used the same rating scales as in Experiment 1.


Univariate ANOVAs on each dependent variable yielded two effects of Day/Night among the six possible effects. Compared to participants who read the Night Incubation instructions, those who read the Day Incubation instructions indicated that they expected the incubation technique to be more likely to make the problem better over the course of ten days compared to the level of the problem at the start of the study (Ms = 8.27, 7.53), and that they would expect to put in more effort (Ms = 6.87, 5.73, Fs (1, 26) = 5.02, 5.05, ps < .05). There were no differences between the night incubation and day incubation instructions on imagined solvability, imagined level of distress at the end of ten days, or the degree to which the incubation technique would be personally helpful or helpful to people in general in solving a problem. The two significant differences are contrary to predictions that the Night Incubation condition would have created unique expectancies of positive outcomes. The failure to find any other significant effects also weakens the expectancy prediction. These data therefore do not support an alternative explanation that the Night Incubation instructions capitalized on an expectancy that nighttime dream incubation would be particularly effective in helping solve personal problems.


The incubation technique used in this study required participants to think of a focal question or concern related to a personal problem, to repeat that problem question over and over while maintaining attention to the question, and then to fall asleep. Conceivably either thinking of a focal question, its repetition with full attention, or both could account for the observed effects. However, since the cognitive review was identical for all Experimental conditions, and since thinking of a focal question was not a time-consuming or elaborate cognitive activity relative to the cognitive review, it seems more likely that attentive repetition or an interaction of repetition and review might account for the results.

If dream process rather than waking cognition produced the reported problem improvements in the current study, what specific mechanisms might account for the effect? One possibility is that attentive repetition might increase the production of counterfactuals in dream content. Counterfactual thinking involves reconstructions of past events in terms of alternative actions or conditions that could lead to different outcomes. Different types of counterfactuals have been shown to either improve mood or to improve performance (Roese, 1994, 1997). Work on counterfactual thinking has been integrated with more general models of cognitive reflection and evaluation that are central to problem solving (e.g., Markman & McMullen, 2003).

Recently McNamara has suggested and provided evidence that dream content may also contain counterfactuals (McNamara, 2000; McNamara, Andresen, Arrowood, & Messer, 2002) which may serve as simulations of problem resolution. This model is similar to Revonsuo’s (2000) functional theory of dream cognition as preparation for coping with threat, except that McNamara does not necessarily invoke an evolutionary base for dream counterfactual thinking. It might be, then, that dream counterfactuals, possibly operating through metaphoric rather than literal rehearsal, independently contribute to either mood improvement or improved problem solving. Perhaps the nature of the incubation question could influence whether dream counterfactuals affect mood or performance (Roese, 1994). Posing a question in and of itself implies alternative endings or conditions, and the attentive repetition of a question may trigger dream counterfactual thinking which persists through the night. Future research should address how dream incubation techniques might affect the quantity and quality of dream counterfactuals.

It is possible that the specific moods affected by night incubation would depend on the nature of the focal problem. It is reasonable to assume that for student participants in this sample, interpersonal and academic problems (by far the most likely focal problems chosen) might have produced anxious and depressed daytime moods. However, the differential efficacy of incubation on specific mood states has not been researched.

Unlike previous research, dream frequency was unrelated to daytime level of anxious, depressed, or angry moods or daytime vigor and confusion. Fewer dreams were recalled if daytime fatigue was high. It might be that the lack of correlation between day mood and dream frequency in this study is related to the use of a non-clinical sample while others have usually used clinical samples (Cartwright, Luten, Young, Mercer, & Bears, 1998; Cartwright, Young, Mercer, Bears, 1998; Hartmann, 1998; Strauch, & Meier, 1992; Zadra, O’Brien, & Donderi, 1998). However, dream frequency was positively correlated with mood self-ratings of dream anxiety, dream depression, dream anger, dream vigor, and dream fatigue. Since there was no difference among conditions in dream frequency, dream frequency in itself cannot account for the effectiveness of night incubation. However, the correlations suggest that the intensity of emotional processing in dreams is related to the frequency with which dreams are recalled.

It would be desirable in future research to replicate the effect of dream incubation techniques on more objective measures of problem-solving processes or problem outcomes. Such measures would be more useful if they took into account the idiosyncratic nature of participants’ problems. In the realm of clinical assessment, it has proven easier to devise objective measures of improvement in mood or cognition than for improvement in specific problem features presented by clients (Haynes, Nelson, & Blaine, 1999).

Finally, the current study does not address whether the dream incubation technique would be effective without use of a waking cognitive review. Delaney (1996) employs a cognitive review prior to use of the attentive repetition of a focal question method used in this study. In clinical situations it would be unusual if there were not some degree of cognitive review prior to the use of any incubation technique. Comparison of night incubation vs. control conditions does not resolve this problem since in this study such comparisons confound incubation technique and cognitive review.


The authors would like to thank Ms. Katie Klassen and Ms. Jennifer McManus for their

assistance in conducting this research. Portions of this research were presented at the 18th International Conference of the Association for the Study of Dreams, University of California, Santa Cruz, July 2001.


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Table 1.  Means and Standard Deviations for Focal Problem Solvability, Distress, Improvement, and Effort by Condition and Time of Measurement









5.14 (.94)

4.76 (1.16)

5.69 (1.01)

4.90 (1.37)

4.61 (1.85)



6.23 (.81)

5.00 (1.89)

5.75 (1.69)

5.33 (1.95)

4.78 (1.59)



5.41 (.67)

4.72 (1.17)

4.81 (1.28)

4.60 (1.45)

5.11 (1.37)



3.48 (1.37)

4.64 (1.25)

4.56 (1.50)

4.73 (1.49)

4.78 (1.52)



9.32 (1.86)

6.88 (2.20)

7.19 (2.90)

7.07 (2.02)

6.33 (2.35)



5.50 (1.19)

5.36 (1.32)

4.75 (1.13)

5.53 (.92)

5.00 (1.72)

Note. NI = Night Incubation (n = 22), NR = Night Relaxation (n = 25), DI = Day Incubation (n = 16), DR = Day Relaxation (n = 15), C = Control (n = 18). Standard deviations are in parentheses. A yoked method was used to assign control participants a focal problem. Higher scores indicate greater solvability, distress and effort on a range of 1 - 7. Higher scores indicate greater improvement on a range of 1 - 12. There are no pre improvement or effort scores.

1Department of Psychology, National University, Redding Academic Center, Redding, California.

2Ashland, Oregon.

3Correspondence should be directed to Gregory L. White, Department of Psychology, National University, Redding Academic Center, 2195 Larkspur Lane, Redding, California, 96002.

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