Insights During Sleep
Valentina Perdomo
Student number: 10004297 Supervisor: dr. Lucia Talamini Co-assessor: dr. Winni Hofman University of Amsterdam Word count: 6189
Abstract
The exact function of sleep mentation (NREM and REM dreams) still eludes the scientific community up to date. Many ideas have been considered; from the original Freudian idea that dreams represent the royal road to the unconscious, to modern approaches rooted in neurobiology that state that dreams are simply a byproduct of random neural activity. This research project focused on the possibility that sleep mentation might serve to benefit waking states through working on daytime problems during sleep. Here we exploratively investigated the occurrence and characteristics of aware sleep-related insights in a large population sample through a questionnaire approach. Various findings emerged, such as the relatively frequent occurrence of this phenomenon and its relationship to sleep disorders such as Narcolepsy. This study was the first of its kind and replication is warranted before a definite conclusion can be made on this phenomenon. Possibly, with the benefit of future research on this topic we might get closer to understanding the function of sleep mentation.
Preface
Many theories have attempted to explain the nature and significance of sleep mentation. Perhaps the best-known theory is attributed to Freud who argued that dreaming represents the royal road to the unconscious (Freud, 1953). Psychoanalytical theories have since been left behind for the scientific approach rooted in neurobiology. The activation-synthesis hypothesis (Mccarley & Hobson, 1977) argues that dreaming is the cognitive byproduct of a physiological state, in which the major source of input is “random” neural activity. However, in between these two extremes appears to be a new uprising of ideas related to both NREM and REM sleep mentation. These will be discussed in the research report to follow.
Table of Contents
Abstract ii
Preface iii
Table of Contents iv
To Sleep on It: The Ability of Gaining Insights During Sleep 1
Methods 5
Data Pre-Processing and Normality Testing 6
Research Results 8
Conclusion and Discussion 16
References 20
Appendix A 25
Addendum I 26
Addendum II 30
To Sleep on It: The Ability of Gaining Insights During Sleep
To many people alike in our society, sleep is seen as nothing more than a sad necessity, a waste of valuable time that could otherwise be better spent on conscious waking pursuits. Sleep duration has decreased up to two hours over the last four decades (National Sleep Foundation, 2008). It has been shown that our society neglects its sleep in place of the use of nighttime technology, such as watching television (Calamaro et al., 2009). Subsequently, living the 24/7 lifestyles carries with it its own negative
consequences such as earlier mortality and decreased cognitive performance (Kripke et al., 2002; Fortier-Brochu et al., 2012). If the importance and benefits of sleep were better understood, this could lead to people taking it more seriously.
Scientific literature has already been suggesting certain benefits of sleep for the waking state. For example, extensive literature supports the role of sleep in memory consolidation (Stickgold et al., 2001; Talamini et al., 2008; Diekelmann & Born, 2010). However, there may be more benefits for cognition than are currently known. For
instance, in the last decade additional findings have started to emerge suggesting a role of sleep in gaining insights (Wagner et al. 2004; Maquet & Ruby, 2004; Cai et al., 2009; Beijamini et al., 2014). Nevertheless, cognitive enhancement from other sleep benefits unrelated to gaining insights cannot be excluded in these studies. Furthermore, with the exception of the study of Beijamini et al. (2014), these studies did not investigate the ongoing mental activity during sleep, which could have contributed to the sleep-related insights. After all, mental activity occurs not only during waking states but also during sleep (Arkin et al., 1978). It is therefore of interest to investigate whether mental activity during sleep, hereinafter referred to as sleep mentation can contribute to sleep-related insights and problem solving.
Sleep itself can be divided into NREM (N1, N2, N3) and REM sleep following the guidelines of the American Academy of Sleep Medicine (AASM) standards (2007).
NREM sleep and REM sleep alternate through the night in a cyclical fashion. Most slow-wave NREM sleep occurs in the first part of the night with REM sleep episodes becoming longer throughout the night (Natural Patterns of Sleep | Healthy Sleep, 2007). The
cognitive characteristics of these two stages are distinctly different from one another (Antrobus, 1990). Pertaining to sleep mentation, dream reports indicate that different types of sleep mentation occur in the two major sleep stages. Mentation reports obtained after REM sleep awakenings tend to be more bizarre and emotionally charged than after NREM sleep, which are reported to be more logical, thought-like and linked to current concerns (Hobson & Stickgold, 1994; Fosse et al., 2004; Kales et al., 1967).
Physiological studies offer additional support for differential brain activity during NREM and REM sleep (Braun et al., 1998; Maquet et al., 1996). REM sleep is associated with activation of limbic and paralimbic regions and an attenuation of activity in the primary visual cortex and frontal association areas including the lateral orbitofrontal cortex and dorsolateral prefrontal, as compared to waking (Braun et al., 1998). NREM sleep generally shows a decrease in global cerebral energy metabolism (i.e., O2 or glucose utilization) relative to waking and REM (Maquet et al. 1997). Furthermore NREM sleep was associated with deactivation within the thalamus, pontine brain stem, orbitofrontal cortex, anterior cingulate cortex and lateral prefrontal cortex as compared to waking (Andersson et al. 1998; Braun et al. 1997; Hofle et al. 1997; Maquet et al. 1997)
Possibly, the deactivation of the (dorso)lateral prefrontal cortex and corresponding loss of top-down control during both NREM and REM sleep may lead to greater creativity and insights (Limb & Braun, 2008, cited in Kahn & Gover, 2010). Furthermore, given also the differences in brain activation between these two states, these stages of sleep may induce disparate forms of sleep mentation that are contributing to insight in distinct ways. Therefore, it may that that theoretical insights are primarily related to NREM sleep given that NREM sleep mentation are reported to be more logical, thought-like and linked to
current concerns. Conversely, emotional insights may be more likely to be related to REM sleep given the emotionally charged nature of REM sleep mentation.
Interestingly, anecdotal evidence of such insight-related sleep mentation exists of many famous scientists and artists that were aware of this phenomenon (see table 1 for an overview). Perhaps the most famous example is the conception of the simple structure for Benzene by August Kekulé (Hubert, 1985). In the words of August Kekulé (Rothenberg, 1995):
I turned the chair to face the fireplace and slipped into a languorous state. Again atoms fluttered before my eyes. Smaller groups stayed mostly in the background this time. My mind’s eye, sharpened by repeated visions of this sort, now
distinguished larger figures in manifold shapes. Long rows, frequently linked more densely; everything in motion, winding and turning like snakes. And lo, what was that? One of the snakes grabbed its own tail and the image whirled mockingly before my eyes. I came to my senses as though struck by lightning. (p. 425) Edgar Allen Poe describes a similar phenomenon in his poem Marginalia (1981) (see Appendix A for a citing). Both August Kekulé and Edgar Allen Poe appear to describe hypnagogic states, which offer insights or lead to increases of creativity. Salvador Dalí went as far as to design a method to purportedly tap into hypnagogic states by slumbering with a key in his hand that would drop upon falling asleep, waking him (Dali, 1992; Nielsen, 1991). Hypnagogic states occur during N1, in which thoughts start becoming more similar to dreams and the experience of these are quite common in Narcolepsy (Kerkhof & Koenen, 2001; Ohayon et al., 1996). A previous study has indeed shown that training students in the willful use of hypnagogia led to an enhancement of creativity (Boynton, 2001). Thus it appears that one of the most well supported methods of
obtaining sleep-related insights is related to the experience of hypnagogic imagery during light sleep.
The combined evidence suggests that sleep may contribute to problem solving by engendering insights and that certain individuals may be aware of this function of sleep. Here we exploratively investigate the occurrence and characteristics of aware sleep-related insights in a large population sample through a questionnaire approach. The relationship between sleep-related insights and the period of sleep will be investigated. We will also assess whether theoretical and emotional insights are related to dreams. It is expected that theoretical insights would occur more often during early night sleep (NREM sleep dominant) and not be related to dreams due to the thought-like nature of NREM sleep mentation. Conversely, it is expected that emotional sleep-related insights would occur more often during late night to early morning sleep (REM dominant) and be related to dreams due to the dreamlike nature of REM sleep mentation. Relationships will also be sought between sleep-related insights and various sleep disorders. It is expected that the strongest correlation with sleep-related insights be found for Narcolepsy, as a
characteristic of Narcolepsy entails the experience of hypnagogic imagery, which appears to play a role in the sleep-related insights in the cases described. Furthermore, exploratory analyses will be carried out to investigate whether there is a relationship between I.Q. and school grades (as measured by the Raven’s progressive matrices and reported high-school grades) and sleep-related insights (Raven, 2000). The reason being that the known cases who have experienced sleep-related insights represent a rather gifted group of individuals, thus it may be a trait that correlates with intelligence. (see table 1).
Table 1. Individuals Who Have Ascribed Scientific and Creative Insights to Sleep
Individual Method Innovation Citation
Otto Loewi Passive Principle of chemical neural transmission
Mazzarello, 2000 Elias Howe Passive The sewing machine Kaempffert, 1924 Dmitri Mendeleev Passive. The periodic table Strahern, 2000 Thomas Edison Active: Holding a hand of ball
bearings while going to sleep.
Various scientific inventions.
Green (2012) August Kekulé Passive The benzene ring Rothenberg (1995) Salvador Dalí Active: Holding a key on top of a
plate while going to sleep.
Surrealistic art. Dalí (1992) Edgar Allen Poe Active: No described method Poetry Poe (1981) Robert Lewis
Stevenson
Passive Key scenes for his novel, dr. Jekyl and mr. Hyde
Methods Subjects
434 first-year Psychology students from the University of Amsterdam participated in this research as part of the first year mandatory test-sessions (Testzittingen).
Materials
Subjects were required to fill in the sleep mentation questionnaire devised by Lucia Talamini (see addendum I for the questionnaire) to measure the occurrence and characteristics of sleep-related insights. The questionnaire consisted of 28 items. Item one through 15 (subscale one) of the questionnaire measured the occurrence and
characteristics of sleep-related insights utilizing a 5-point Likert-scale (never, sometimes, regularly, often, always). Item 16 through 23 assessed the relationship between time of day of and creativity and analytical thinking utilizing a 5-point likert scale (1=helemaal niet van toepassing through 5=volledig van toepassing). Item 24 through 28 were only applicable for subjects who had experience with sleep-related insights and investigated how the type of sleep related insight (theoretical or emotional) related to sleep mentation content and which period of sleep it occurred in using a categorical answer format. For more extensive characteristics of sleep, subjects were required to fill in the Sleep-50 questionnaire (Spoormaker et al., 2005). Subjects were also required to provide high-school grades and fill in the Raven’s progressive matrices for an estimate of intelligence (Raven, 2000).
Procedure
Subjects were subjected to five different test-sessions lasting approximately two hours each. Within this time, the subjects were required to fill in an array of computer based questionnaires, among which also the questionnaires pertaining to this study.
Data analyses
Data Pre-Processing and Normality Testing Data Filtering
All subjects filled in the sleep mentation questionnaire during the mandatory test-sessions of the University. It is alleged that a proportion of the subjects do not take this task as seriously as they should. This allegation was corroborated by the relatively limited time in seconds spent filling in the questionnaire by the 434 subjects (M=163.15,
SD=64.86, minimum= 34, maximum 489). Therefore the data were filtered in an attempt to remove subjects who did not take filling in the questionnaire seriously.
Even though the original questionnaire does not contain reverse scored items (when the answer to an item should be in reverse order to another item measuring the same construct as a method for reducing response bias), it is possible to infer the
genuineness of answers based on item 24, 25 and 26 (see addendum I). Given that item 24 asks the subject to specify which type of sleep-related insights he/she experiences, it is unreasoned for the subject to answer item 24 stating that he/she experiences a form of sleep-related insight and then to answer the follow up questionnaire item(s) (item 25/26) stating that he does not experience sleep-related insights. Subjects were removed who committed this error (removal of 122 subjects).
Also, the time spent filling in the questionnaire was calculated for all subjects. Given that it takes on average 3 minutes (180 seconds) to attentively fill in the 28-item questionnaire, it was chosen to filter out subjects who took less than 2.5 minutes (150 seconds) to do so. This led to the removal of an additional 126 subjects, leaving 186 subjects, with a reported mean time spent filling in the questionnaire of 207.04 seconds (SD=56.74, minimum=151, maximum=489). Although this may appear as a conservative estimate of subjects who took the questionnaire seriously, it was chosen to run the
following tests on this smaller subsample given the notoriety of subjects randomly filling in questionnaires to be finished faster during the test sessions.
Internal Consistency of Questionnaire
The internal consistency of the items of subscale one of the sleep mentation questionnaire was calculated. The internal consistency is a measure based on the correlations between different item scores on the same subscale of a test. It measures whether items that propose to measure the same general construct produce similar scores. This was done utilizing Cronbach’s Reliability Analysis as the measure of internal
consistency, of which the formula is:
This subscale appeared to have good internal consistency: Cronbach’s α=.849. All items appeared worthy of retention: The greatest increase in alpha would come from deleting item 1, but that would lead to only a marginal increase of Cronbach’s α by .03. It was therefore decided to retain all items of subscale one. However, given that the internal consistency is a measure based on correlations between item scores, the internal
consistency may have been artificially enhanced if certain students were systematically filling in only one answer option for all items (e.g. vaak) while not reading the questions to have the questionnaire finished faster.
Normality testing
The items of subscale one of the sleep mentation questionnaire were non-normally distributed. After transformation, (both with square-root transformation and
log-transformation) the data still deviated from normality (i.e. all items had significant Kolmogorov-Smirnov test scores). Given that transforming the data twice would lead to issues of interpretability of the results, it was decided to use non-parametric statistics.
a º N2Cov
s2
Research Results
The Occurrence of Sleep-Related Insights
The occurrence of sleep mentation was investigated by calculating the means and percentages of occurrence for items of subscale one (see Table 2 and 3). 81.7% of subjects claim to obtain useful insights or (partial) solutions of daytime problems during sleep (item 3) and 38.7% experience this regularly, often or always (M=2.35, SD=0.96). Insights were most common during half-sleep before falling asleep (item 5) (81.7%) with 39.9% experiencing this regularly, often or always (M=2.41, SD=1.02). This is in accord with the reports of for example Edgar Allen Poe and August Kekulé that state that insights occur in a state of half-sleep when falling asleep. Less common methods were waking up in the morning with a solution (item 8) (74.2% | 17.2%) and waking up in the middle of the night (item 6) with a solution (44.6% | 9.7%).
Setting the intention before sleep to gain insights during sleep is less common than the experience itself. The percentage of subjects setting an intention before going to sleep to obtain sleep-related insights (item 10 through 14) ranged between 19.4% and 28.5% and those claiming to experience this regularly, often or always ranged between 4.3% and 9.7%. Setting the intention to gain insights resulted most commonly in insight dreams (item 14) (28.5% | 9.7%). Furthermore, the percentage of subjects who reported strictly experiencing theoretical sleep-related insights was much less (7.2%) than for subjects reporting emotional sleep-related insights (48.5%) or both (44.3%).
Therefore awareness over sleep-related insight appears to be a relatively common phenomenon within this population. Sleep-related insights were reported most often to occur in a state of half-sleep before falling asleep, in accord with the cases described. Setting an intention to obtain sleep-related insights was a less common occurrence than the phenomenon itself and theoretical sleep-related insights were less commonly reported than emotional sleep-related insights.
Characteristics of Sleep-Related Insights
Chi-square tests of goodness-of-fit were performed to investigate how theoretical and emotional insights were distributed across the sleep period (i.e. early vs. late night) and across sleep mentation content (related to dreams and not related to dreams). This was
done utilizing the following formula:
The expected value was an equal distribution across answer options (the null hypothesis). Subjects who reported not experiencing sleep insights were removed from item 25 and 26 to test whether there was an equal distribution of sleep insights (theoretical and emotional) and sleep mentation content (whether or not it was related to dreams). Sleep mentation content for theoretical insights (item 26) was unequally distributed, χ2(1, N= 127)= 39.69,
p < .001. Insights into theoretical problems were more often not related to dreams than
related to dreams. This may be due to theoretical sleep mentation being related more to NREM sleep mentation, which is known to contain more thought-like mentation rather than perceptually vivid dreams. Emotional insights (item 25) were equally distributed across sleep mentation content, χ2(1, N= 164)= .98, p < .755. This is against the prediction that emotional sleep mentation be more often related to dreams than not.
To test whether there was an equal distribution of sleep-related insights
(theoretical and emotional) across the sleep period, subjects were removed who did not know when this occurs and those who stated not to experience sleep insights. There was an unequal distribution for theoretical insights (item 28) and which part of the night they occur in (χ2(2, N= 27)= 10.67, p = .005) as well as for emotional insights (item 27) and which part of the night they occur in (χ2(2, N= 47)= 8.34, p = .015). It appears that both of these effects are driven by the low number of subjects reporting that it occurs during the second part of the night (7 for emotional related insights and 1 for theoretical sleep-related insights). Removing this answer option (that it occurs during the second part of the
X2= (observed- expected)2 expected
night) and testing whether there is an association between the type of sleep insight and early night (first part) and late night/early morning sleep (3rd part of when waking up) led to no significant results for either theoretical insights, χ2(2, N= 26)= 0, p = 1, or emotional insights, χ2(2, N= 40)= .900, p = .343. Therefore, there was no evidence found for
theoretical sleep-related insights occurring during the early part of the night and emotional sleep-related insights occurring during the later part of the night.
Sleep-Related Insights and I.Q. scores and High School Grades
By means of Spearman's rank correlation coefficient analyses, the correlations were calculated between the items of subscale one and I.Q. scores as measured by the Raven’s progressive matrices. The Spearman's rank correlation coefficient analysis is a nonparametric measure of statistical dependence between two variables, of which the
formula is:
ρ=1− 6
∑
di2
n(n2−1)
Three significant correlations were found, namely between I.Q. and item 6 (rs(186)
= .145, p = .049), item 10 (rs(186) = .146, p < .047) and item 13 (rs(186) = .174, p < .017).
Furthermore, testing for correlations using the Spearman’s rank correlation coefficient between mean high school grades for exact science (math, physics, chemistry, biology and computer science) and language courses (English, Dutch, German and French) as measured by the Social Economic Status (SES) questionnaire and items of subscale one led to one significant correlation. This was for a correlation between the mean grade for the exact science courses and item 14, rs(66) = .278, p = .024 (dropout rate
of 64.5% due to data-loss). These were relatively low correlations to draw any definite conclusions. However, it could be that the level of awareness over the phenomenon and the causality of setting an intention to obtain sleep-related insights may be related to greater intelligence.
Table 2. Minimum, Maximum, Mean scores and Standard Deviations for the Likert-Scale
Items Measuring sleep problem solving (N=186)
Min. Max. M SD
1. Ik heb het gevoel dat ik tijdens mijn slaap informatie zit te
herverwerken 1 5 3.10 1.07
2. Tijdens de slaap of in halfslaap komen er wel eens interessante ideeën tot mij, die echter, wanneer ik er bij vol bewustzijn aan terug denk, nergens op blijken te slaan.
1 5 2.34 1.05
3. Tijdens de slaap kom ik wel eens tot nuttige inzichten of (deel)oplossingen voor problemen die mij overdag
bezighouden.
1 5 2.35 0.96
4. Tijdens de slaap heb ik wel eens nuttige gedachten of dromen met betrekking tot problemen die mij bezig houden. Ik weet dit omdat ik mij deze gedachten of dromen kan herinneren wanneer ik wakker wordt.
1 5 2.35 1.11
5. In de halfslaap, voordat ik echt helemaal in slaap val, kom ik wel eens tot nuttige inzichten over problemen die mij bezig houden.
1 5 2.41 1.02
6. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker met een inzicht of (deel)oplossing.
1 5 1.59 0.80
7. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker, denkend aan het probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
1 5 1.59 0.78
8. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend vaak wakker met een inzicht of
(deel)oplossing.
1 5 1.94 0.72
9. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend wel eens wakker, denkend aan het
probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
1 4 1.83 0.77
10. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik in de loop van de nacht soms wakker met nuttige inzichten over het probleem.
1 4 1.25 .55
11. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik ‘s ochtends soms wakker met nuttige inzichten over het probleem.
1 4 1.30 .61
12. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten van halfslaap gedurende de nacht, krijg ik soms nuttige ideeën over het probleem.
1 5 1.30 0.63
13. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten van halfslaap in de vroege ochtend, krijg ik soms nuttige ideeën over het probleem.
1 3 1.26 0.53
14. Ik denk expres voor het slapen gaan aan bepaalde problemen, omdat ik weet dat ik soms dromen heb die op de een of andere manier nuttige inzichten bieden over dat probleem.
1 5 1.43 0.80
15. Wanneer ik net wakker ben geworden, maar nog in een soort halfslaap verkeer, heb ik vaak creatieve ideeën. Deze zijn, wanneer ik er bij vol bewustzijn aan terug denk, misschien wat naïef of niet helemaal kloppend, maar toch bruikbaar.
Table 3. The occurrence and regular occurrence in percentages of subjects claiming to
experience sleep-related problem solving within this population (N=186).
Occurrence* Regular occurrence** 1. Ik heb het gevoel dat ik tijdens mijn slaap informatie zit te
herverwerken 93 67.7
2. Tijdens de slaap of in halfslaap komen er wel eens interessante ideeën tot mij, die echter, wanneer ik er bij vol bewustzijn aan terug denk, nergens op blijken te slaan.
79.6 34.5
3. Tijdens de slaap kom ik wel eens tot nuttige inzichten of (deel)oplossingen voor problemen die mij overdag
bezighouden.
81.7 38.7
4. Tijdens de slaap heb ik wel eens nuttige gedachten of dromen met betrekking tot problemen die mij bezig houden. Ik weet dit omdat ik mij deze gedachten of dromen kan herinneren wanneer ik wakker wordt.
75.8 36.5
5. In de halfslaap, voordat ik echt helemaal in slaap val, kom ik wel eens tot nuttige inzichten over problemen die mij bezig houden.
81.7 39.9
6. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker met een inzicht of (deel)oplossing.
44.6 9.7
7. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker, denkend aan het probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
44.6 10.8
8. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend vaak wakker met een inzicht of
(deel)oplossing.
74.2 17.2
9. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend wel eens wakker, denkend aan het
probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
64.5 14.6
10. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik in de loop van de nacht soms wakker met nuttige inzichten over het probleem.
19.4 4.8
11. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik ‘s ochtends soms wakker met nuttige inzichten over het probleem.
22.6 5.9
12. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten van halfslaap gedurende de nacht, krijg ik soms nuttige ideeën over het probleem.
23.1 5.3
13. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten van halfslaap in de vroege ochtend, krijg ik soms nuttige ideeën over het probleem.
22 4.3
14. Ik denk expres voor het slapen gaan aan bepaalde problemen, omdat ik weet dat ik soms dromen heb die op de een of andere manier nuttige inzichten bieden over dat probleem.
28.5 9.7
15. Wanneer ik net wakker ben geworden, maar nog in een soort halfslaap verkeer, heb ik vaak creatieve ideeën. Deze zijn, wanneer ik er bij vol bewustzijn aan terug denk, misschien wat naïef of niet helemaal kloppend, maar toch bruikbaar.
63.4 22.1
Note. * The occurrence was calculated by subtracting the percentage of subjects who claimed to never
experience sleep-related problem solving. ** The regular occurrence was calculated by summing the percentage of subjects who claim to experience sleep-related problem solving regularly, often and always.
Clinical Overlap
By means of Spearman's rank correlation coefficient analyses, the correlations were calculated for items of subscale one and the raw scores for the following sleep disorders: Sleep Apnea, Insomnia, Narcolepsy, Periodic Limb Movement Disorder (PLMD), Circadian Rhythm Sleep Disorder (CRSD) (Table 3), as measured with the Sleep-50 Questionnaire (Spoormaker et al., 2005). This entailed an analysis of 181 subjects, with a dropout rate of 2.6% (five subjects) due to these subjects not having filled in the Sleep-50 questionnaire.
There were two correlation coefficients that had at least a medium sized effect (i.e. a correlation coefficient of .3 or higher) (Field, 2009). One of which was for item 7, which measured the occurrence of waking up in the middle of the night while thinking of a problem and obtaining a solution or insight for it, and insomnia, rs(181) = .318, p < .0001.
The relationship between thinking during the night and insomnia is a plausibility as research has suggested that intrusive thoughts are a characteristic symptom of insomnia (Wicklow & Espie, 2002). The intrusive thinking may be beneficial in leadings to insights during the night with the downside of possibly also contributing to symptoms of
insomnia.
The strongest correlation between items of subscale one and sleep disorders were found for item two, which measures the occurrence of obtaining non-useful insight during sleep or halfsleep, and Narcolepsy, rs(181) = .369, p < .0001;. This was expected, as one
of the items measuring Narcolepsy gauges whether the subject sees hypnagogic
hallucinations when falling asleep (Item 17). This is similar to the description of August Kekulé’s sleep inspired insight, which is purported to have occurred in a hypnagogic state (Schacter, 1976).
A follow up analysis was carried out for the items of the sleep mentation
experiencing hypnagogic imagery as measured by item 17 of the Sleep-50 questionnaire. There was a correlation found between experiencing hypnagogic imagery and item two and 12 (rs(181) = .281, p < .0001; rs(181) = .181, p < .011). As explained above, item two
gauges the occurrence of obtaining non-useful insight during sleep or half-sleep. Item 12 gauges the occurrence of intentionally thinking about a problem before sleep as so to receive insights in a state of half-sleep during the night. These correlations were relatively small (<.3) (Field, 2009).
Additionally, to exploratively investigate whether sleep-related insights are strictly related to the experience of hypnagogic imagery or the general construct of Narcolepsy, a follow up Spearman’s rank correlation coefficient analysis was performed on the sleep-related insight items and the items measuring Narcolepsy (see table 5). The most notable finding is that Cataplexy (item 20) is not significantly related to any items measuring sleep-related insights. In this case, if there is a relationship between sleep-related insights and Narcolepsy, it concerns Narcolepsy without Cataplexy. For example, item two, which measures the experience of non-useful sleep-related insights, was significantly correlated to all of the other items measuring Narcolepsy (see table 5). Therefore, it appears that there may be a relationship between sleep-related insight and Narcolepsy symptoms with the exception of Cataplexy.
Table 4. Correlations Between the Likert-Scale Items of the sleep mentation questionnaire
and the Raw Scores for Sleep Disorders as Measured by the Sleep-50 Questionnaire (N=181)
Item Sleep Apnea Insomnia Narcolepsy PLMD CRSD
1 .149* .240** .226** .157* N.S. 2 N.S. .185* .369** .240** N.S. 3 N.S. N.S. .230** .165* N.S. 4 N.S. N.S. .256** N.S. N.S. 5 N.S. .218** .206** .255** .179* 6 N.S. .224** N.S. .177* N.S. 7 N.S. .318** .169* .235** N.S. 8 N.S. .184* N.S. N.S. N.S. 9 N.S. .179* .170* N.S. N.S. 10 N.S. .166* .242** .193** .187* 11 N.S. .237** .208** N.S. .165* 12 N.S. .163* .209** N.S. .148* 13 N.S. N.S. .180* N.S. N.S. 14 N.S. N.S. .173* N.S. .202** 15 N.S. N.S. .196** N.S. N.S.
Note. The correlations were calculated using Spearman's rank correlation coefficient analyses between the
items of subscale one and the raw scores for Sleep Apnea, Insomnia, Narcolepsy, Periodic Limb Movement Disorder (PLMD) and Circadian Rhythm Sleep Disorder (CRSD)), as measured with the Sleep-50
Questionnaire (Spoormaker et al., 2005).
N.S. = not significant (p > .05), * p <.05, ** p <.01.
Table 5. Correlations Between the Likert-Scale Items of the sleep mentation questionnaire
and the likert scale items for Narcolepsy as Measured with the Sleep-50 Questionnaire (N=181)
Item Item 17 Item 18 Item 19 Item 20 Item 21
1 .196** .158* N.S. .177* N.S. 2 .280** .148* .257** N.S. .180* 3 N.S. .204* .234** N.S. .181* 4 N.S. .169* .227** N.S. .186* 5 N.S. .228** .228** N.S. N.S. 6 N.S. N.S. .168* N.S. N.S. 7 N.S. N.S. N.S. N.S. N.S. 8 N.S. N.S. N.S. N.S. N.S. 9 N.S. N.S. .166* N.S. N.S. 10 .183* .289** .148* N.S. .196** 11 .164* .176* N.S. N.S. N.S. 12 .189* .158* N.S. N.S. .152* 13 N.S. .168* N.S. N.S. N.S. 14 .154* .146* N.S. N.S. N.S. 15 N.S. .160* .148* N.S. N.S.
Note. The correlations were calculated using Spearman's rank correlation coefficient analyses between the
items of subscale one and the following Narcolepsy items as measured with the Sleep-50 questionnaire (Spoormaker et al., 2005): item 17: Seeing dreamlike images when falling asleep; item 18: Falling asleep during social gatherings; item 19: Experiencing sleep attacks; Item 20: experiencing muscle weakness with intense emotions and item 21: Experiencing sleep paralysis.
Conclusion and Discussion
This study investigated the occurrence and characteristics of aware sleep-related insights. A large part of the student population was aware of experiencing this
phenomenon. Obtaining insights while in a state of half-sleep before falling asleep was the most common form of sleep-related insight reported. Obtaining insights during sleep and when waking up were less commonly reported. This is in accord with anecdotal evidence of reports describing that insights occur in the state of half-sleep. Also, setting the intention to gain insights during sleep is less common than the experience itself. It could be hypothesized that an additional level of awareness over this phenomenon would be needed for this and may therefore be a reason of why it is less common.
With regards to the type of insight, it appears that obtaining strictly theoretical insights was less common that obtaining emotional or both kinds of insights. Also, insights into theoretical problems were more often not related to dreams than related to dreams. This may be due to theoretical insight being related to NREM sleep mentation, which is known to contain more thought-like mentation rather than perceptually vivid dreams. Nevertheless, this questionnaire did not contain an answer option gauging if theoretical insights are related to thought-like sleep mentation. Therefore, it is not possible
to tease apart whether theoretical sleep insights are more characteristic of NREM sleep mentation or whether subjects were simply unable to recall the sleep mentation related to the insights obtained. Also, evidence did not support the idea that emotional insights are related to REM sleep.
It appears that both theoretical sleep-related insights as emotional sleep-related insights were distributed unequally across the night. This was caused due to a limited number of subjects (<10) reporting that it occurs during the second part of the night. This may be related to the amount of times subjects wake up during the night. It may be that if subjects sleep throughout the night or do not recall waking up, it would be unlikely for
them to be able to self-report that they experienced insights during the second part of sleep. There was no difference in distribution of early and late night sleep insights for either theoretical or emotional sleep-related insights. Therefore the evidence gathered so far does not support the idea of theoretical sleep-related insights being related more to NREM sleep mentation and emotional sleep-related insights to REM sleep mentation.
Pertaining to sleep-related insights and intelligence, relatively weak relationships were found between I.Q. and sleep-related insights. There was a stronger relationship found for exact science high school grades and intentionally thinking about a problem before going to sleep to obtain insights in dreams. However, this pertained to strictly one of the 15 items of the questionnaire. A possible reason for only obtaining only one correlation was the relatively high drop-out rate of participants (64.5%). This was due to data-loss by the organization collecting the data.
The strongest association between sleep-related insights and sleep disorders was found for non-useful insights during half-sleep or sleep and Narcolepsy. This was
expected, as a characteristic of Narcolepsy entails experiencing hypnagogic imagery when falling asleep, which has been described in sleep-related insights reported. Investigating whether sleep-related insights are strictly related to the experience of hypnagogic imagery or the general construct of Narcolepsy led to no particular item driving the correlation. It appears that all symptoms, with the notable exception of Cataplexy, correlate to various degrees to at least certain types of sleep-related insights. This would have to be better established with future research, however a relationship may exist between sleep-related insights and symptoms of Narcolepsy without Cataplexy. Furthermore an additional relationship of interest was between thinking during the night and insomnia. It may be that the intrusive thinking characteristic of insomnia may be beneficial in leadings to insights during the night.
To conclude, the findings support the occurrence of sleep-related insights and an approximate representation of the characteristics of the phenomenon is starting to appear. However, this study was the first of its kind and follow up research is needed to provide stronger evidence for the findings obtained up to now. Furthermore, the questionnaire quality was not optimal, containing relatively long items (all items with the exception of item 1). Certain items (item 4 and 15) also contained more than one statement per item. Furthermore, the population polled consisted of first year Psychology students who were polled during the test-sessions and are known to not take this task seriously. In
combination of these two factors, it likely led to non-optimal data quality.
However, even given the circumstances, this study did provide a greater idea of the occurrence and characteristics of sleep-related insights within the population than what was known before. Analyses of this questionnaire data also provided insights on how to improve a follow up questionnaire. This was undertaken with the help of a trained Psychometrician specialized in creating questionnaires (see addendum II for the revised questionnaire and elaboration of item construction).
Follow up research should entail repeating this questionnaire study with the revised questionnaire and possibly polling a more trustworthy population. From this new population, it may be useful to select subjects who state to gain insights from hypnagogic states and train them in the willful use of this state by means of biofeedback as was undertaken in the study of Boynton (2001). This group can then be compared to a control group based on performance on creativity and insight tasks both before and after the intervention. This could serve to tease apart if obtaining half-sleep sleep-related insights is a skill that is strictly learned or whether it entails a more engrained predisposition.
An additional idea may be to poll different populations aside from only a student population to investigate if there are differences in the extent of occurrence and
to experience sleep-related insights than a more blue-collared population. Given that the new questionnaire was constructed with the general population in mind (e.g. all items were constructed using simple phrasing that can be easily understood by the large
majority of the general population), this could be a relatively easily undertaken endeavor. This study provides additional support for benefits of sleep and its processes. In particular, it appears that there is a large percentage of the population that may be aware of sleep-related insights and some who even intentionally utilize sleep for this benefit. Possibly, obtaining sleep-related insights can be a skill that the entire population can develop and benefit from. Perhaps awareness of the insight-related potentiality of sleep may lead to more people taking sleep seriously. Furthermore, with enigmatic descriptions of August Kekulé and Edgar Allen Poe, it is of unquestionable interest of science to better understand aware sleep-related insights and further research is warranted.
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Appendix 1
Edgar Allen Poe’s description of aware sleep mentation (Poe, 1981):
There is, however, a class of fancies, of exquisite delicacy, which are not thoughts, and to which, as yet, I have found it absolutely impossible to adapt language. I use the word fancies at random, and merely because I must use some word; but the idea commonly attached to the term is not even remotely applicable to the
shadows of shadows in question. They seem to me rather psychal than intellectual. They arise in the soul (alas, how rarely!) only at its epochs of most intense
tranquility-when the bodily and mental health are in perfection-and at those mere points of time where the confines of the waking world blend with those of the world of dreams. I am aware of these "fancies" only when I am upon the very brink of sleep, with the consciousness that I am so. I have satisfied myself that this condition exists but for an inappreciable point of time-yet it is crowded with these "shadows of shadows"; and for absolute thought there is demanded time's
Addendum I:
VRAGENLIJST SLAAP MENTATIE
Geef voor elke stelling aan hoe vaak dit jou overkomt. Kies per vraag 1 antwoord optie.
Antwoord opties: Nooit, soms, regelmatig, vaak, altijd.
1. Ik heb het gevoel dat ik tijdens mijn slaap informatie zit te herverwerken.
2. Tijdens de slaap of in halfslaap komen er wel eens interessante ideeën tot mij, die echter, wanneer ik er bij vol bewustzijn aan terug denk, nergens op blijken te slaan. 3. Tijdens de slaap kom ik wel eens tot nuttige inzichten of (deel)oplossingen voor
problemen die mij overdag bezighouden.
4. Tijdens de slaap heb ik wel eens nuttige gedachten of dromen met betrekking tot problemen die mij bezig houden. Ik weet dit omdat ik mij deze gedachten of dromen kan herinneren wanneer ik wakker wordt.
5. In de halfslaap, voordat ik echt helemaal in slaap val, kom ik wel eens tot nuttige inzichten over problemen die mij bezig houden.
6. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker met een inzicht of (deel)oplossing.
7. Wanneer er een probleem is dat mij bezig houdt word ik midden in de nacht wel eens wakker, denkend aan het probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
8. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend vaak wakker met een inzicht of (deel)oplossing.
9. Wanneer er een probleem is dat mij bezig houdt word ik de volgende ochtend wel eens wakker, denkend aan het probleem, en kom ik in een staat van halfslaap tot inzichten of oplossingen.
10. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik in de loop van de nacht soms wakker met nuttige inzichten over het probleem.
11. Ik denk expres voor het slapen gaan aan bepaalde problemen, want als ik dit doe wordt ik ’s ochtends soms wakker met nuttige inzichten over het probleem.
12. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten van halfslaap gedurende de nacht, krijg ik soms nuttige ideeën over het probleem. 13. Ik denk expres voor het slapen gaan aan bepaalde problemen, want tijdens momenten
van halfslaap in de vroege ochtend, krijg ik soms nuttige ideeën over het probleem. 14. Ik denk expres voor het slapen gaan aan bepaalde problemen, omdat ik weet dat ik
soms dromen heb die op de een of andere manier nuttige inzichten bieden over dat probleem.
15. Wanneer ik net wakker ben geworden, maar nog in een soort halfslaap verkeer, heb ik vaak creatieve ideeën. Deze zijn, wanneer ik er bij vol bewustzijn aan terug denk, misschien wat naïef of niet helemaal kloppend, maar toch bruikbaar.
In hoeverre zijn de volgende stellingen op jou van toepassing? Kies per vraag 1 antwoord optie.
Antwoordopties: Likert schaal van 1 t/m 5 (1=helemaal niet van toepassing; 5=volledig van toepassing).
16. ’s Ochtends, kort na het ontwaken, heb ik mijn meest creatieve gedachten. 17. Midden op de dag heb ik mijn meest creatieve gedachten.
18. ’s Avonds laat heb ik mijn meest creatieve gedachten.
19. Wanneer ik ‘s nachts wakker wordt heb ik mijn meest creatieve gedachten. 20. ’s Ochtends vroeg kan ik het scherpst analytisch denken.
21. Midden op de dag kan ik het scherpst analytisch denken. 22. ’s Avonds laat kan ik het scherpst analytisch denken.
23. Wanneer ik ‘s nachts wakker wordt kan ik het scherpst analytisch denken.
De volgende vragen zijn alleen van toepassing als je wel eens een relatie tussen slaap en probleem oplossing hebt ervaren. Kies uit de antwoord opties telkens degene die voor jou het meest opgaat.
24. De problemen waarover ik tijdens de (half)slaap inzichten krijg zijn… a. overwegend van persoonlijke, emotionele aard.
b. overwegend niet-emotioneel, maar eerder theoretisch of praktisch van aard. c. soms van type 1 en soms van type 2.
25. De verkregen inzichten met betrekking tot persoonlijke, emotionele problemen zijn… a. gerelateerd aan de dromen die ik mij ’s ochtends nog herinner.
b. niet gerelateerd aan dergelijke dromen.
c. Dit soort nachtelijke probleem oplossing overkomt mij niet.
26. De verkregen inzichten met betrekking tot theoretische of praktische problemen zijn…
a. gerelateerd aan de dromen die ik mij ’s ochtends nog herinner. b. niet gerelateerd aan dergelijke dromen.
c. Dit soort nachtelijke probleem oplossing overkomt mij niet.
27. Inzichten over persoonlijke, emotionele problemen komen tot mij… a. gedurende het eerste derde deel van mijn slaap.
b. gedurende het 2e derde deel van mijn slaap
c. gedurende het laatste derde deel van mijn slaap of bij het definitief ontwaken in de ochtend.
d. Ik weet het niet.
e. Dit soort nachtelijke probleem oplossing overkomt mij niet.
28. Inzichten over theoretische of praktische problemen komen tot mij… a. gedurende het eerste derde deel van mijn slaap.
b. gedurende het 2e derde deel van mijn slaap
c. gedurende het laatste derde deel van mijn slaap of bij het definitief ontwaken in de ochtend.
d. Ik weet het niet.
e. Dit soort nachtelijke probleem oplossing overkomt mij niet.
Debriefing:
'Slaap mentatie'
Slaap is meer dan een periode van rust en herstel. Recent onderzoek toont aan dat slaap tevens informatie herverwerking en geheugenconsolidatie dient. Enkele bevindingen suggereren bovendien dat slaap ook een rol zou kunnen spelen in de reorganisatie van informatie en het komen tot nieuwe inzichten. Er zijn enkele casussen bekend van mensen bij wie dit fenomeen heel duidelijk optreedt. Deze mensen ervaren dat zij gedurende de slaap tot oplossingen komen voor problemen die hen bezighouden. De vragenlijst 'Slaap mentatie' wil het vóórkomen en de aard van deze fenomenen in kaart brengen."
Addendum II:
Revised Questionnaire,
Elaboration of Items & General Test
Construction Tips
Revised Questionnaire
Header: Denken tijdens je slaap?
Toelichting:
De volgende vragen gaan over het idee dat mensen denken tijdens de slaap. Wij zijn erg geïnteresseerd of u zoiets ook ooit hebt meegemaakt. Probeer na te gaan wat u ervan vindt en wat u hebt meegemaakt.
Lees a.u.b. iedere uitspraak door en geef aan in hoeverre deze op u van toepassing is. Antwoord opties: niet, een beetje, tamelijk goed, zeer goed.
1. Tijdens mijn slaap werken mijn hersenen door met over wat ik overdag heb meegemaakt.
2. Na er een nacht op geslapen te hebben kan ik beter een oplossing bedenken voor een probleem.
3. Het is moeilijk voor te stellen dat ik tijdens mijn slaap problemen van overdag kan oplossen.
4. Na een nacht slapen heb ik meer inzicht in kwesties die mij overdag hebben bezig gehouden dan ervoor.
5. Tijdens de slaap kom ik wel eens tot inzichten over problemen die mij overdag bezig hebben gehouden.
6. Tijdens de slaap kom ik wel eens tot deeloplossingen voor problemen die mij overdag hebben bezig gehouden.
7. Tijdens de slaap kom ik wel eens tot volledige oplossingen voor problemen die mij overdag hebben bezig gehouden.
8. Als ik voor het slapen gaan denk aan bepaalde problemen krijg ik in mijn slaap vaak een inzicht hierover.
9. Voor het slapen gaan denk ik vaak expres aan bepaalde problemen om ‘s nachts tot inzichten te komen.
Hypothesis on NREM and REM sleep stages in relation to Theoretical and Emotional sleep mentation
Toelichting:
De volgende vragen gaan over de relatie tussen inzichten tijdens de slaap en andere factoren. Deze vragen maken gebruik van andere antwoordmogelijkheden dan hierboven. Alles wijst zich van zelf.
11. Welke van de volgende uitspraken is voor u van toepasing?
De inzichten tijdens de slaap hebben betrekking op emotionele problemen (zaken waarin je gevoelens een grote rol spelen).
De inzichten tijdens de slaap hebben betrekking op rationele problemen (zaken waarin je gevoelens geen grote rol spelen) van aard.
De inzichten tijdens de slaap hebben betrekking op zowel emotionele als rationele problemen.
Ik heb nooit inzichten gehad tijdens de slaap.
12. Inzichten in emotionele problemen als gevolg van mijn slaap krijg ik: nooit
terwijl ik slaap
In halfslaap, voordat ik echt in slaap val In halfslaap, tijdens mijn slaapperiode
in halfslaap, als ik na mijn slaapperiode bijna wakker ben geworden ’na mijn slaapperiode, als ik al wakker ben
13. Inzichten in rationele problemen als gevolg van mijn slaap krijg ik: nooit
terwijl ik slaap
In halfslaap, voordat ik echt in slaap val In halfslaap, gedurende de nacht
in halfslaap, ‘s ochtends tijdens het ontwaken ‘s ochtends als ik al wakker ben
Questions gauging the qualitative aspects of sleep mentation to see whether the sleep mentation is related to thinking, dreaming, both or neither.
Toelichting:
Uit onderzoek is bekend dat tijdens de slaap gedachten en dromen voorkomen. Dit gebeurd bij iedereen, alhoewel de mate waarin mensen zich hier na het ontwaken nog iets van kunnen herinneren sterk verschilt van persoon tot persoon. Het fenomeen dromen is bij de meeste mensen bekend en betreft de vaak bizarre beelden en verhalen die wij tijdens de slaap kunnen ervaren. Minder bekend zijn de slaap-gerelateerde
gedachtenprocessen. Deze vertonen enige gelijkenis met gedachtenprocessen tijdens de waakstaat: de gedachten zijn overwegend logisch en plausibel. Verreweg de meeste mensen kunnen zich, bij ontwaken, niets van de slaapgedachten herinneren en zijn zich dus ook niet bewust van dit fenomeen. De slaapgedachten zijn over het algemeen niet gebonden aan uitgesproken visuele beelden en film-achtige plots, zoals typerend voor de dromen die velen van ons zich wel herinneren. De volgende vragen gaan over deze twee slaap-gerelateerde processen en hun mogelijke relatie met het verkrijgen van inzichten tijdens slaap.
14. Als ik in mijn slaap tot inzichten van emotionele aard kom, dan zijn die vaak gekoppeld aan:
levendige, filmachtige dromen die ik me herinner gedachten in de slaap die ik me herinner
zowel dromen als slaapgedachten die ik me herinner niet te herleiden tot dromen of gedachten tijdens de slaap ik verkrijg in mijn slaap geen inzichten van emotionele aard 15. Als ik in mijn slaap tot inzichten van rationele aard kom, dan zijn die vaak
gekoppeld aan:
levendige, filmachtige dromen die ik me herinner gedachten in de slaap die ik me herinner
zowel dromen als slaapgedachten die ik me herinner niet te herleiden tot dromen of gedachten tijdens de slaap ik heb geen inzichten van rationele aard tijdens of na de slaap
Questions regarding dream sleep mentation
Toelichting:
De volgende vragen gaan over dromen, die u wellicht hebt gehad en die gerelateerd zijn aan tijdens de slaap verworven inzichten. Dat wil zeggen dat u door een droom, of tijdens een droom tot een bepaald inzicht bent gekomen. Als u niet bekend bent met dit soort dromen, of helemaal niet ervaart dat u tijdens de slaap tot inzichten komt, kunt u telkens de laatste antwoord optie kiezen.
16. Wanneer ik dromen heb die tot inzichten leiden zijn deze: levendiger dan andere dromen
even levendig als andere dromen minder levendig dan andere dromen ik ervaar zulke dromen niet
Lees a.u.b. iedere uitspraak door en geef aan in hoeverre deze op u van toepassing is. Antwoord opties: niet, een beetje, tamelijk veel, zeer veel, ik ervaar deze dromen niet.
17. De dromen die tot inzichten leiden verstoren mijn slaap.
18. Tijdens deze ‘inzichtelijke dromen’ kan ik meer controle uitoefenen op de droom dan tijdens andere soorten dromen.
19. Tijdens deze ‘inzichtelijke dromen’ kan ik minder controle uitoefenen op de droom dan tijdens andere dromen.
Questions regarding thinking sleep mentation
Toelichting:
De volgende vragen hebben betrekking op de eerder genoemde denkprocessen tijdens de slaap en zijn gericht op mensen die zich mogelijk in meer of mindere mate van dit proces bewust zijn. Als u het beschreven slaap-denken nooit ervaren hebt, kunt u telkens de laatste antwoord optie kiezen.
20. Tijdens de slaap denk ik over problemen die mij overdag hadden bezig gehouden.
21. Tijdens de slaap ben ik mij bewust van dit denkproces.
22. Tijdens de slaap kan ik weinig controle uitoefenen op dit denkproces.
23. Als ik gedurende dit denkproces tijdens de slaap een oplossing heb bedacht, word ik hiervan wakker.
24. Dit denkproces gebeurt automatisch (ik hoef er geen moeite voor te doen). 25. Tijdens de slaap heb ik controle over dit denkproces.
26. Dit denkproces verstoort mijn slaap.
Is er verder nog iets hierover dat je ons hierover wilt vertellen?
Elaboration of Items
Items 1 through 10 gauge the general experience of sleeping and gaining insights into daytime problems.
Whether or not the subject perceives continual information processing during sleep (1), in particular in relation to solving problems (2 (indicative), 3 (contra-indicative).
General improvement of insights as a result of sleep (4)
Insights (5) and solutions during sleep, in progressive order of magnitude of solution (6, 7)
Awareness over this phenomenon (8) and to consciously utilize it (9). Waking up as a result of an insight (10)
The answer options are similar to the sleep-50 questionnaire (niet, een beetje, tamelijk goed, zeer goed). It thus consisted of a 4-point likert scale.
Items 11 through 13 look into how NREM and REM sleep stages relate to Theoretical and Emotional sleep mentation.
Gauge which type of sleep mentation the subject experiences (11) Which stage of sleep this sleep mentation occurs (12, 13)
Items 14 and 15 gauge the qualitative aspects of sleep mentation to see whether sleep mentation is related to thinking, dreaming, both or neither.
Here dreaming sleep mentation is defined as lively film-like dreams while thinking sleep mentation is defined as thinking during sleep.
Item 16 through 19 look into the qualitative aspects of dreams related to insights. The answer options for item 17 through 19 consist of the 4-point likert scale.
Investigating where this phenomenon isn’t strictly lucid dreaming (16, 18 (Indicative), 19 (Contra-indicative))
Possible sleep disturbances as a result of insight dreams (17)
Item 20 through 26 look into the qualitative aspects of thinking sleep mentation The answer options consist of the 4-point likert scale.
The ability of thinking sleep mentation (20) Awareness over thought process (21) Ability of controlling thought process (22)
The amount of effort given to incite thinking sleep mentation (24)
Algemene Testconstructie Tips van Harrie Vorst:
1. Vermijd dubbele vragen.
De items moeten slechts één idee bevatten.
2. Vermijd directe ontkenningen.
Het is aan te bevelen om zowel indicatieve als contra-indicatieve items in een schaal op te nemen. Gebruik maken van gelijke aantallen indicatieve e contra-indicatieve items in een schaal voorkomt vertekening door de instem- of
ontkenningsantwoordtendentie. Vooral de contra-indicatieve zijn echter moeilijk te construeren omdat directe ontkenningen (woorden als ‘niet’, ‘geen’ en ‘nooit’) vermeden moeten worden. Het probleem met directe ontkenningen is dat ze in combinatie met de negative antwoordcategorieën een dubbele ontkenning kunnen opleveren. Bovendien worden woorden als ‘niet’, ‘nooit’ en ‘geen’ vaan over het hoofd gezien.
Directe ontkenningen zijn vaak te vermijden door ontkennende voorvoegsels (in-, im-, on-) te gebruiken.
Een andere mogelijkheid om directe ontkenningen te vermijden is de frequentie of intensiteit van het beschreven gedrag te minimaliseren (maak gebruik van bijv. Zelden, weinig, nauwelijks.
3. Zet het belangrijkste idee aan het eind van het item.
De gedachte achter deze regels os dat voorkomen moet worden dat respondenten voorbarig een antwoord formuleren. Veelal zijn de items stellingen die bestaan uiten een conditie en gedragsbeschrijving. Omdat de conditie van de
doorslaggevende betekenis is voor een juiste interpretatie door de respondent, dient deze altijd vooraf te gaan aan het gedrag. Mensen vormen zich tijdens het lezen van de uitspraak een oordeel. Als het oordeel aanvankelijk gebaseerd is op het gedrag, zonder kennis van de conditie, is men minder geneigd dat
aanvankelijke oordeel alsnog aan te passen aan de condities.
4. Vermijd feitelijke uitspraken; doe geen aannames of respondenten.
Als een item bestaat uit een conditie en een gedragsbeschrijving, moet de conditie zodanig geformuleerd worden dat iedereen zich erin kan vinden. Als dit niet het geval is, dan kunnen respondenten het oneens zijn met de in de conditie
geformuleerde stelling en is de respons niet meet eenduidig toe te wijzen aan de gedragsbeschrijving.
