Table 1.

Interview questions and content analysis scale.

The interview questions inExperiments 1 and 2. Interview questions 1–6 were presented to each participant in the same way, and depending on the answers, further details (A→) were inquired when applicable.
1. Did you dream during anaesthesia/sleep?  If the participant answered YES, content of the experience was assessed with:  A. Describe the dream in as much detail as possible.  B. Where were you, and what the environment of the dream was like? What happened in the dream? What did you see? What did you hear? What did you sense and feel? What did you do? Were you alone? Were there other characters in the dream? What did they do? Did anything else happen?  C. Did you have the dream just before the awakening?  D. Did you experience feelings/emotions in your dream? What kinds of feelings or emotions did you experience? What dream situation were the emotions related to? Was the dream pleasant or unpleasant?  If the participant answered NO, recall certainty was assessed:  A. Are you certain you did not dream?  B. Do you feel you might have been dreaming but forgot what the dream was about?
2. Did you experience anything related to this room or situation during anaesthesia/sleep?  If the participant answered YES:  A. Describe the experience in as much detail as possible.  B. What happened? Who were involved? What was the environment like? Do you recall any additional details?  If the participant answered NO, the next question was presented.
3. Did you hear anything during anaesthesia/sleep?  If the participant answered YES:  A. Describe what you heard in as much detail as possible.  B. Can you describe the sounds you heard? Can you describe the speaker's gender? Can you describe the tone or content of what was said?  If the participant answered NO, the next question was presented.
4. Did you sense anything during anaesthesia/sleep?  If the participant answered YES:  A. Describe what you sensed in as much detail as possible.  B. Was the sensation unpleasant or painful? What was the pain like? What part of your body was affected?  If the participant answered NO, the next question was presented.
5. Do you remember anything else from during anaesthesia/sleep that you have not already mentioned?
6. What is the last thing you remember before falling asleep? What is the first thing you remember after awakening? (These questions were asked after UR3 in Experiment 1 and after each awakening in Experiment 2.)
The content analysis scale for the classification of the interview reports. All interview transcripts were coded by two independent raters, and in case of disagreement, the content of the report was discussed until an agreement was reached or the final decision was made by a third judge.Inter-rateragreement in all stages of content analysis was substantial in both experiments, ranging from 86.8% to 98.5% between different classifications (Ҡ-values ranging from 0.736 to 0.972; allP-values <0.001).
Stage 1. All interviews were coded for recall of experiences
No recall	The participant regained responsiveness but was adamant he did not experience anything during unresponsiveness
White report	The participant reported having a strong impression that he had had experiences during unresponsiveness but could not recall any explicit content
Content report	The participant reported having had experiences that have most evidently taken place during the period of unresponsiveness
Stage 2. Content reports were further coded to include disconnected and/or connected content
Disconnected experiences
Dreaming	Purely internally generated hallucinatory content that was not directly related to or did not originate from the research environment
Memory incorporation	Experiences that realistically or in distorted form depicted objects, persons, events, or sensations/feelings related to the research setting and to which the participant had been exposed to before unresponsiveness/sleep
Connected experiences
Awareness	Externally generated experiences that were related to objects/persons that had been present, or events that had occurred, during the session, but the occurrence of which the participant could not have anticipated, and which thus could not be categorised as memory incorporation
Stage 3. Perceptual complexity and dynamics of experience were coded separately for dream-like experiences, memory incorporation, and awareness
No sensory–perceptual content	Thought-like, non-perceptual content
Static experience	An isolated, fragmentary, and typically unisensory percept or several connected percepts without temporal progressions occurring within or between percepts
Dynamic experience	Complex, connected, and typically multisensory percepts, which are located within a scene, with temporal progression occurring either between percepts within a scene or between scenes
Stage 4. Modality of experiences was coded separately for dreaming, memory incorporation, and awareness
Sensory–perceptual experiences	Visual, auditory, gustatory, olfactory, interoceptive (e.g. hunger, thirst, heartbeat, and breathing), kinaesthetic/vestibular, tactile, or noci- and thermoceptive experiences
Affective states	Positive and negative moods and emotions
Cognition	Thoughts, memories, inner speech, planning, and reflection of content of consciousness
Out-of-body experience	Observing one's body or the research environment from outside one's physical body
Sense of presence	Sensing a presence of another person/being in the room