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Publications (10 of 12) Show all publications
Sikka, P. (2019). How to Study Dream Experiences (1ed.). In: Robert J. Hoss, Katja Valli, Robert P. Gongloff (Ed.), Dreams: Understanding Biology, Psychology, and Culture Volume 1 (pp. 153-166). Santa Barbara, CA: Greenwood, an Imprint of ABC-CLIO, LLC
Open this publication in new window or tab >>How to Study Dream Experiences
2019 (English)In: Dreams: Understanding Biology, Psychology, and Culture Volume 1 / [ed] Robert J. Hoss, Katja Valli, Robert P. Gongloff, Santa Barbara, CA: Greenwood, an Imprint of ABC-CLIO, LLC , 2019, 1, p. 153-166Chapter in book (Refereed)
Abstract [en]

In the scientific study of dreams, as in the scientific study of any other topic, it is important to first clearly define the phenomenon one is investigating. The definition determines what exactly is being studied. Then, the methods for collecting and analyzing data regarding this phenomenon need to be chosen. These methods determine what kind of results are obtained, to what extent the results reflect the phenomenon of interest, and whether the results can be trusted. This chapter gives an overview of how dream experiences are scientifically studied: how dreams and dreaming are defined, what kinds of methods are used to collect and analyze dream data, and what aspects need to be considered when conducting and reading studies that investigate dream experiences (see also Kahan & Horton, 2012, and Zadra & Domhoff, 2017).

Place, publisher, year, edition, pages
Santa Barbara, CA: Greenwood, an Imprint of ABC-CLIO, LLC, 2019 Edition: 1
Keywords
dreaming, methodology
National Category
Natural Sciences Psychology
Research subject
Consciousness and Cognitive Neuroscience
Identifiers
urn:nbn:se:his:diva-16590 (URN)978-1-4408-5616-7 (ISBN)978-1-4408-5617-4 (ISBN)978-1-4408-5618-1 (ISBN)
Available from: 2019-01-30 Created: 2019-01-30 Last updated: 2019-03-12
Sikka, P., Revonsuo, A., Sandman, N., Tuominen, J. & Valli, K. (2018). Dream emotions: a comparison of home dream reports with laboratory early and late REM dream reports. Journal of Sleep Research, 27(2), 206-214
Open this publication in new window or tab >>Dream emotions: a comparison of home dream reports with laboratory early and late REM dream reports
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2018 (English)In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 2, p. 206-214Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to compare the emotional content of dream reports collected at home upon morning awakenings with those collectedin the laboratory upon early and late rapid eye movement (REM) sleep awakenings. Eighteen adults (11 women, seven men; mean age = 25.89 ± 4.85) wrote down their home dreams every morning immediately upon awakening during a 7-day period. Participants also spent two non-consecutive nights in the sleep laboratory where they were awoken 5 min into each continuous REM sleep stage, upon which they gave a verbal dream report. The content of a total of 151 home and 120 laboratory dream reports was analysed by two blind judges using the modified Differential Emotions Scale. It was found that: (1) home dream reports were more emotional than laboratory early REM dream reports, but not more emotional than laboratory late REM dream reports; (2) home dream reports contained a higher density of emotions than laboratory (early or late REM) dream reports; and (3) home dream reports were more negative than laboratory dream reports, but differences between home and early REM reports were larger than those between home and late REM reports. The results suggest that differences between home and laboratory dream reports in overall emotionality may be due to the time of night effect. Whether differences in the density of emotions and negative emotionality are due to sleep environment or due to different reporting procedures and time spent in a sleep stage, respectively, remains to be determined in future studies.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
dreams, dreaming, emotions, content analysis, REM sleep, sleep stages
National Category
Psychology
Research subject
Consciousness and Cognitive Neuroscience
Identifiers
urn:nbn:se:his:diva-13634 (URN)10.1111/jsr.12555 (DOI)000426866500008 ()28568911 (PubMedID)2-s2.0-85020126304 (Scopus ID)
Available from: 2017-06-06 Created: 2017-06-06 Last updated: 2018-05-17Bibliographically approved
Sikka, P., Pesonen, H. & Revonsuo, A. (2018). Peace of mind and anxiety in the waking state are related to the affective content of dreams. Scientific Reports, 8, Article ID 12762.
Open this publication in new window or tab >>Peace of mind and anxiety in the waking state are related to the affective content of dreams
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 12762Article in journal (Refereed) Published
Abstract [en]

Waking mental well-being is assumed to be tightly linked to sleep and the affective content of dreams. However, empirical research is scant and has mostly focused on ill-being by studying the dreams of people with psychopathology. We explored the relationship between waking well-being and dream affect by measuring not only symptoms of ill-being but also different types and components of well-being. Importantly, this is the first time peace of mind was investigated as a distinct aspect of well-being in a Western sample and in relation to dream content. Healthy participants completed a well-being questionnaire, followed by a three-week daily dream diary and ratings of dream affect. Multilevel analyses showed that peace of mind was related to positive dream affect, whereas symptoms of anxiety were related to negative dream affect. Moreover, waking measures were better related to affect expressed in dream reports rather than participants’ self-ratings of dream affect. We propose that whereas anxiety may reflect affect dysregulation in waking and dreaming, peace of mind reflects enhanced affect regulation in both states of consciousness. Therefore, dream reports may possibly serve as markers of mental health. Finally, our study shows that peace of mind complements existing conceptualizations and measures of well-being.

Keywords
adult, anxiety, article, consciousness, controlled study, dreaming, human, mental health, multilevel, analysis, questionnaire, wakefulness, wellbeing
National Category
Natural Sciences Neurosciences
Research subject
Consciousness and Cognitive Neuroscience
Identifiers
urn:nbn:se:his:diva-16080 (URN)10.1038/s41598-018-30721-1 (DOI)000442606800008 ()30143673 (PubMedID)2-s2.0-85052246506 (Scopus ID)
Available from: 2018-08-24 Created: 2018-08-24 Last updated: 2018-10-22Bibliographically approved
Sikka, P., Feilhauer, D., Valli, K. & Revonsuo, A. (2017). How You Measure Is What You Get: Differences in Self- and External Ratings of Emotional Experiences in Home Dreams. American Journal of Psychology, 130(3), 367-384
Open this publication in new window or tab >>How You Measure Is What You Get: Differences in Self- and External Ratings of Emotional Experiences in Home Dreams
2017 (English)In: American Journal of Psychology, ISSN 0002-9556, E-ISSN 1939-8298, Vol. 130, no 3, p. 367-384Article in journal (Refereed) Published
Abstract [en]

This study demonstrates that different methods for measuring emotional experiences in dreams — self-ratings of dreams using emotion rating scales versus external ratings in the form of content analysis of narrative dream reports — can lead to strikingly different results and contradicting conclusions about the emotional content of home dreams. During 3 consecutive weeks, every morning upon awakening, 44 participants (16 men, 28 women, average age 26.9± 5.1 years) reported their dreams and rated their emotional experiences in those dreams using the modified Differential Emotions Scale. Two external judges rated emotional experiences inthe same 552 (M = 12.55 ± 5.72) home dream reports using the same scale. Comparison of the 2 methods showed that with self-ratings dreams were rated as more emotional and more positive than with external ratings. Moreover, whereas with self-ratings the majority of dreams was rated as positively valenced, with external ratings the majority of dream reports was rated as negatively valenced. Although self- and external ratings converge, at least partially, in the measurement of negative emotional experiences, they diverge greatly in the measurement of positive emotional experiences. On one hand, this discrepancy may result from different biases inherent in the 2 measurement methods highlighting the need to develop better methods for measuring emotional experiences. On the other hand, self- and external ratings may capture different phenomena and should thus be considered complementary and used concurrently. Nevertheless, results suggest that negative emotional experiences can be measured in a more valid and reliable manner than positive emotional experiences.

Place, publisher, year, edition, pages
Illinois, US: , 2017
Keywords
emotions, dreaming, dream emotions, content analysis, gender differences
National Category
Natural Sciences Psychology
Research subject
Consciousness and Cognitive Neuroscience
Identifiers
urn:nbn:se:his:diva-14074 (URN)10.5406/amerjpsyc.130.3.0367 (DOI)000407872700010 ()2-s2.0-85027696254 (Scopus ID)
Note

Diana Feilhauer is now at the Department of Philosophy, Lund University, Sweden.

This research was supported by the Signe and Ane GyllenbergFoundation (P.S.), the Finnish Cultural Foundation (P.S.), and Academy of Finland (K.V., A.R.) (project 266434).

The authors thank Linnéa Stenström for assistance in the early phases of the study.

Available from: 2017-09-03 Created: 2017-09-03 Last updated: 2017-11-27Bibliographically approved
Sikka, P., Revonsuo, A. & Valli, K. (2016). Methodological Issues in Measuring Dream Emotions. In: : . Paper presented at The 33rd Annual International Dream Conference (organized by the International Association for the Study of Dreams), Kerkrade, the Netherlands, June 24-28, 2016.
Open this publication in new window or tab >>Methodological Issues in Measuring Dream Emotions
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Emotions are central in dreams, specifically in rapid eye movement sleep dreams. Despite a wealth of research on the emotional content of dreams, there is little consensus about the overall emotionality and predominant valence of dreams or about the prevailing specific emotions in dreams. Previous contradictory findings are arguably due to unresolved methodological issues. However, studies that have directly investigated these methodological issues are scarce. In this presentation three studies that investigated the effect of study methodology on the frequency, valence and phenomenological content of dream emotions are discussed. The studies demonstrate that the use of different methods for rating dream emotions (participants who experience the dream vs external judges who analysed the respective dream report) and for collecting dream reports (home vs laboratory setting) leads to very different results and conclusions about the emotional content of dreams. As such, these studies highlight the importance of carefully considering study methodology when conducting and interpreting dream (emotional) content studies.

National Category
Natural Sciences Other Biological Topics Psychology (excluding Applied Psychology)
Research subject
Natural sciences; Humanities and Social sciences
Identifiers
urn:nbn:se:his:diva-12193 (URN)
Conference
The 33rd Annual International Dream Conference (organized by the International Association for the Study of Dreams), Kerkrade, the Netherlands, June 24-28, 2016
Available from: 2016-05-02 Created: 2016-05-02 Last updated: 2017-11-27Bibliographically approved
Sikka, P., Valli, K., Virta, T. & Revonsuo, A. (2014). I know how you felt last night, or do I?: Self- and external ratings of emotions in REM dreams. Consciousness and Cognition, 25, 51-66
Open this publication in new window or tab >>I know how you felt last night, or do I?: Self- and external ratings of emotions in REM dreams
2014 (English)In: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 25, p. 51-66Article in journal (Refereed) Published
Abstract [en]

We investigated whether inconsistencies in previous studies regarding emotional experiencesin dreams derive from whether dream emotions are self-rated or externally evaluated.Seventeen subjects were monitored with polysomnography in the sleep laboratoryand awakened from every rapid eye movement (REM) sleep stage 5 min after the onsetof the stage. Upon awakening, participants gave an oral dream report and rated their dreamemotions using the modified Differential Emotions Scale, whereas external judges rated theparticipants’ emotions expressed in the dream reports, using the same scale. The twoapproaches produced diverging results. Self-ratings, as compared to external ratings,resulted in greater estimates of (a) emotional dreams; (b) positively valenced dreams;(c) positive and negative emotions per dream; and (d) various discrete emotions representedin dreams. The results suggest that this is mostly due to the underrepresentationof positive emotions in dream reports. Possible reasons for this discrepancy are discussed.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
REM sleep, Dreaming, Emotions, Content analysis, Modified Differential Emotions Scale
National Category
Psychology (excluding Applied Psychology) Natural Sciences Other Biological Topics
Research subject
Humanities and Social sciences; Natural sciences
Identifiers
urn:nbn:se:his:diva-10454 (URN)10.1016/j.concog.2014.01.011 (DOI)000333228100007 ()24565868 (PubMedID)2-s2.0-84894325874 (Scopus ID)
Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
Sikka, P., Valli, K., Virta, T. & Revonsuo, A. (2012). Subjective and objective measures of affective states in REM sleep dreams. In: : . Paper presented at The 16th annual meeting of the Association for the Scientific Study of Consciousness (ASSC16), Brighton, UK, July 2-6, 2012.
Open this publication in new window or tab >>Subjective and objective measures of affective states in REM sleep dreams
2012 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Biological Sciences Other Biological Topics Psychology (excluding Applied Psychology)
Research subject
Natural sciences; Humanities and Social sciences
Identifiers
urn:nbn:se:his:diva-12191 (URN)
Conference
The 16th annual meeting of the Association for the Scientific Study of Consciousness (ASSC16), Brighton, UK, July 2-6, 2012
Available from: 2016-05-02 Created: 2016-05-02 Last updated: 2017-11-27Bibliographically approved
Kallio, S., Hyönä, J., Revonsuo, A., Sikka, P. & Nummenmaa, L. (2011). The Existence of a Hypnotic State Revealed by Eye Movements. PLoS ONE, 6(10), Article ID e26374.
Open this publication in new window or tab >>The Existence of a Hypnotic State Revealed by Eye Movements
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2011 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 10, article id e26374Article in journal (Refereed) Published
Place, publisher, year, edition, pages
PLoS ONE, 2011
National Category
Natural Sciences
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-5601 (URN)10.1371/journal.pone.0026374 (DOI)000296515200016 ()22039474 (PubMedID)2-s2.0-80055034195 (Scopus ID)
Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
Sikka, P., Walker, R., Cockayne, R., Wood, M. J. A., Harrison, P. J. & Burnet, P. W. J. (2010). D-Serine metabolism in C6 glioma cells: Involvement of alanine-serine-cysteine transporter (ASCT2) and serine racemase (SRR) but not D-amino acid oxidase (DAO). Journal of Neuroscience Research, 88(8), 1829-1840
Open this publication in new window or tab >>D-Serine metabolism in C6 glioma cells: Involvement of alanine-serine-cysteine transporter (ASCT2) and serine racemase (SRR) but not D-amino acid oxidase (DAO)
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2010 (English)In: Journal of Neuroscience Research, ISSN 0360-4012, E-ISSN 1097-4547, Vol. 88, no 8, p. 1829-1840Article in journal (Refereed) Published
Abstract [en]

D-serine is an endogenous N-methyl-D-aspartate (NMDA) receptor coagonist. It is synthesized from L-serine by serine racemase (SRR), but many aspects of its metabolism remain unclear, especially in the forebrain, which lacks active D-amino acid oxidase (DAO), the major D-serine degradative enzyme. Candidate mechanisms include SRR operating in alpha,beta-eliminase mode (converting D-serine to pyruvate) and regulation by serine transport, in which the alanine-serine-cysteine transporter ASCT2 is implicated. Here we report studies in C6 glioma cells, which "simulate" the forebrain, in that the cells express SRR and ASCT2 but lack DAO activity. We measured D-serine, ASCT2, SRR, and DAO expression and DAO activity in two situations: after incubation of cells for 48 hr with serine isomers and after increased or decreased SRR expression by transfection and RNA interference, respectively. Incubation with serine enantiomers decreased [(3)H]D-serine uptake and ASCT2 mRNA and increased SRR immunoreactivity but did not alter DAO immunoreactivity, and DAO activity remained undetectable. SRR overexpression increased D-serine and pyruvate and decreased [(3)H]D-serine uptake and ASCT2 mRNA but did not affect DAO. SRR knockdown did not alter any of the parameters. Our data suggest that D-serine transport mediated by ASCT2 contributes prominently to D-serine homeostasis when DAO activity is absent. The factors regulating D-serine are important for understanding normal NMDA receptor function and because D-serine, along with DAO and SRR, is implicated in the pathogenesis and treatment of schizophrenia.

Place, publisher, year, edition, pages
John Wiley & Sons, 2010
Keywords
D-serine, eliminase, racemase, uptake, transporter, glia, DAAO
National Category
Biochemistry and Molecular Biology
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-12195 (URN)10.1002/jnr.22332 (DOI)000277245500021 ()20091774 (PubMedID)2-s2.0-77952386888 (Scopus ID)
Available from: 2016-05-02 Created: 2016-05-02 Last updated: 2017-11-30Bibliographically approved
Revonsuo, A., Kallio, S. & Sikka, P. (2009). What is an altered state of consciousness?. Philosophical Psychology, 22(2), 187-204
Open this publication in new window or tab >>What is an altered state of consciousness?
2009 (English)In: Philosophical Psychology, ISSN 0951-5089, E-ISSN 1465-394X, Vol. 22, no 2, p. 187-204Article in journal (Refereed) Published
Abstract [en]

‘‘Altered State of Consciousness’’ (ASC) has been defined as a changed overall pattern of conscious experience, or as the subjective feeling and explicit recognition that one’s own subjective experience has changed. We argue that these traditional definitions fail to draw a clear line between altered and normal states of consciousness (NSC). We outline a new definition of ASC and argue that the proper way to understand the concept of ASC is to regard it as a representational notion: the alteration that has happened is not an alteration of consciousness (or subjective experience) per se, but an alteration in the informational or representational relationships between consciousness and the world. An altered state of consciousness is defined as a state in which the neurocognitive background mechanisms of consciousness have an increased tendency to produce misrepresentations such as hallucinations, delusions, and memory distortions. Paradigm examples of such generally misrepresentational, temporary, and reversible states are dreaming, psychotic episodes, psychedelic drug experiences, some epileptic seizures, and hypnosis in highly hypnotizable subjects. The representational definition of ASC should be applied in the theoretical and empirical studies of ASCs to unify and clarify the conceptual basis of ASC research.

Place, publisher, year, edition, pages
Routledge, 2009
Keywords
ASC, Dreaming, Drug Induced States, Hypnosis, Meditation, Psychosis, State of consciousness
National Category
Natural Sciences
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-3009 (URN)10.1080/09515080902802850 (DOI)000264826600004 ()2-s2.0-69249214200 (Scopus ID)
Available from: 2009-05-07 Created: 2009-05-07 Last updated: 2017-12-28Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1926-6138

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