REM_Turku

Dream EEG and Mentation (DREAM) data set

---Data set information---

Common name: REM_Turku

Full name: REM_Turku

Authors: Pilleriin Sikka, Antti Revonsuo, Valdas Noreika, and Katja Valli

Location: Turku, Finland

Year: N/A

Set ID: [SET BY DATABASE]

Amendment: [SET BY DATABASE]

Corresponding author ID: [SET BY DATABASE]

Download URL: [SET BY DATABASE]

Correspondence:

Pilleriin Sikka ([e-mail]), Katja Valli ([e-mail])

---Metadata---

Key ID: [SET BY DATABASE]

Date entered: [SET BY DATABASE]

Number of samples: [INFERRED BY DATABASE]

Number of subjects: [INFERRED BY DATABASE]

Proportion REM: [INFERRED BY DATABASE]

Proportion N1: [INFERRED BY DATABASE]

Proportion N2: [INFERRED BY DATABASE]

Proportion experience: [INFERRED BY DATABASE]

Proportion no-experience: [INFERRED BY DATABASE]

Proportion healthy: [INFERRED BY DATABASE]

Provoked awakening: Yes

Time of awakening: Night

Form of response: Free

Date approved: [SET BY DATABASE]

---How to decode data files---

The PSG files are raw (i.e., not preprocessed) EEG data files and 

include the last 2 minutes of preawakening EEG from each REM episode 

obtained using a serial awakening paradigm in the sleep laboratory. 

Data set includes EEG data from 134 awakenings of 18 participants.

Files are organized according to the format: /Data/PSG/casexx_syy, where

xx refers to Case ID 

yy refers to Subject ID 

In the "Records.csv" file, the following information is presented:

Filename: in the format /Data/PSG/Sxx_yy

Case ID: number of awakening for the subject

Subject ID: unique identifier of subject

Experience: 2 = dream experience; 1 = without recall ("white dream"); 0 = no dream experience

Treatment group: N/A

Duration: duration of the EEG data file in seconds

EEG sample rate: the sampling rate of the EEG in Hertz

Number of EEG channels: the number of EEG signals in this sample

Last sleep stage: the scored sleep stage of the final epoch in the sample

Has EOG: whether EOG is included in the sample (1 = yes; 0 = no)

Has EMG: whether EMG is included in the sample (1 = yes; 0 = no)

Has ECG: whether ECG is included in the sample (1 = yes; 0 = no)

Proportion artifacts: N/A

Time of awakening: time when this sample’s PSG ends

Subject age: age of the subject

Subject sex: sex of the subject (key: 0 = male, 1 = female; 2 = other)

Subject healthy: whether subject is from a relatively healthy population (key: 0 = no; 1 = yes)

Has more data: whether this sample has more data in the form of files under the /Data directory other than the /Data/PSG directory (key: 0=no, 1=yes)

Remarks: The first number refers to the number of experimental night in the sleep lab for the subject, 

the second number refer to the number of awakening during that night (e.g., 1_3 refers to Night 1, Awakening 3). 

Remarks can also include other important information regarding this subject or data file.

In the "Ratings.csv" file, the following information is presented:

Filename: in the format /Data/PSG/casexx_syy

DreamReport_Wordcount: total number of dream-related words minus utterances, fillers, repetitions, corrections, waking commentaries

ER = external ratings of emotions expressed in dream reports, conducted by two blind judges using the Finnish version of the modified Differential Emotions Scale (mDES; Fredrickson, 2013); the number refers to the frequency of occurrence of the emotion item in the dream report 

SR = self-ratings of emotions experienced in the preceding dream using the mDES, conducted by participants themselves upon awakening and after having reported the dream; each item was rated on the scale from 0 = not at all to 4 = extremely much

PA = positive emotion/affect item of mDES

NA = negative emotion/affect item of mDES

The following are the 10 positive and 10 negative emotion/affect items of the mDES scale:

PA1 - Amused_Funloving_Giggly

PA2 - Awe_Wonder_Amazement

PA3 - Grateful_Appreciative_Thankful

PA4 - Hopeful_Optimistic_Encouraged

PA5 - Inspired_Uplifted_Elevated

PA6 - Interested_Alert_Curious

PA7 - Joyful_Glad_Happy

PA8 - Love_Closeness_Trust

PA9 - Proud_Confident_Selfassured

PA10 - Serene_Content_Peaceful

NA1 - Angry_Irritated_Annoyed

NA2 - Ashamed_Humiliated_Disgraced

NA3 - Contemptuous_Scornful_DIsdainful

NA4 - Disgust_Distaste_Revulsion

NA5 - Embarrassed_Selfconscious_Blushing

NA6 - Guilty_Repetant_Blameworthy

NA7 - Hate_Distrust_Suspicion

NA8 - Sad_Downhearted_Unhappy

NA9 - Scared_Fearful_Afraid

NA10 - Stressed_Nervous_Overwhelmed

ER_InferredExpressed = whether the emotion was directly expressed in the dream report or could be inferred from the behaviour of the dream self (key: 1 = expressed, 2 = inferred, 3 = both)

Remarks: any remarks regarding this data file

--Treatment group codes--

N/A

---Experimental description---

A full description of the materials and methods can be found in the following article: 

Sikka, P., Revonsuo, A., Noreika, V., & Valli, K. (2019). 

EEG frontal alpha asymmetry and dream affect: Alpha oscillations over the right frontal cortex during REM sleep and presleep wakefulness predict anger in REM sleep dreams. 

Journal of Neuroscience, 39(24): 4775-4784. https://doi.org/10.1523/JNEUROSCI.2884-18.2019

Participants: 

Healthy, not using medication, right-handed, native Finnish speakers, with good sleep quality (score ≤ 5 on the Pittsburgh Sleep Quality Index; Buysse et al., 1989).

Experimental design and procedure: 

For a Figure displaying the experimental procedure, see Sikka et al. (2019, p. 4777).

Participants spent 2 nights (separated by a week) in the sleep laboratory. In the evening, participants arrived in the laboratory 2h before their usual bedtime. 

First, participants were instructed about the procedure of the study and EEG electrodes attached to their scalp. 

Next, participants' waking state resting EEG was recorded (8 x 1 min; 10:30pm-12:00am) and they rated their current waking affective state 

using the Finnish version of the modified Differential Emotions Scale (fmDES, Fredickrson, 2013). 

Participants were then allowed to fall asleep. Sleep stages were monitored and scored visually (Rechtschaffen and Kales, 1968; Iber et al., 2007).  

Every time REM sleep had lasted continuously for 5 min, and was in a phasic stage, a tone signal was used to awaken the participants. 

Upon awakening, participants provided an oral dream report: first, they reported the last image they had in mind just before awakening, 

followed by a detailed report of the whole dream. Next, participants rated their affective experiences in the preceding dream 

by filling in the fmDES electronically using a mouse and a computer screen above the bed. In case the participants reported ‘‘no dreams’’, 

researchers asked whether they had not had a dream or they felt like they had had a dream but could not recall any specific content (i.e., ‘white dream’). 

In these two cases fmDES was not filled in. Participants were then allowed to continue their sleep. 

This procedure was repeated throughout the night until the final morning awakening (scheduled between 5:30 A.M. to 8:30 A.M.). 

Upon final awakening, and after having reported and rated the last dream, participants were asked to lie in bed but stay awake. Similar to the evening, waking state resting (morning baseline) EEG was then recorded for 8 min, followed by participants’ ratings of their current waking state affect using the fmDES.

--DREAM categorization procedure--

Dream experiences = participants remembered having a dream and were able to report at least some of its content.

Without recall ("white dream" = participants felt like they had had a dream but could not recall any specific content.

No recall = participants reported not having had any dream experiences. 

---Technical details---

N/A

--Data acquisition--

EEG was recorded using 24 single Ag/AgCl electrodes (placed according to standard 10/10 system). 

Additionally, 4 EOG electrodes were used to record eye movements and an EMG electrode (placed on the chin) was used to record muscle activity. 

All electrodes (except the bipolar EOG and EMG electrodes) were references to the right mastoid. The ground electrode was placed on the forehead. 

EEG signal was amplified (SynAmps model 5083), notch-filtered at 50 Hz, digitized at 500 Hz, and recorded with Neuroscan equipment and software. 

All impedances were kept <5 kΩ. 

--Data preprocessing--

Data has not been preprocessed.