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Kristoffer Appel

Institute of Sleep and Dream Technologies, Hamburg 22769, Germany.

3 papers in the library · 136 citations · publishing 2021-2025

Papers

Real-time dialogue between experimenters and dreamers during REM sleep.

Current biology : CB April 12, 2021 Karen R Konkoly, Kristoffer Appel, Emma Chabani et al. 126 citations

People who are asleep and having a lucid dream—aware that they are dreaming—can perceive questions from an experimenter and answer them in real time using eye movements and facial muscle contractions. In a study of 36 individuals during REM sleep, including frequent lucid dreamers, a novice, and a patient with narcolepsy, participants performed perceptual analysis of new information, held information in working memory, computed simple answers, and gave volitional replies. Correct answers occurred on 29 occasions across 6 individuals, documented by four independent laboratories. This two-way communication channel allows real-time interrogation of dream cognition and characteristics.

Electrophysiological Correlates of Lucid Dreaming: Sensor and Source Level Signatures.

The Journal of neuroscience : the official journal of the Society for Neuroscience May 14, 2025 Çağatay Demirel, Jarrod Gott, Kristoffer Appel et al. 8 citations

Lucid dreaming, where a person becomes aware they are dreaming, is linked to REM sleep. To overcome previous research limitations, a new preprocessing pipeline was applied to pooled EEG data from multiple labs. Sensor-level differences between lucid and nonlucid REM sleep were minimal, but source-level analysis revealed reduced beta power (12-30 Hz) in right central and parietal areas, including the temporoparietal junction, during lucid dreaming. Alpha-band (8-12 Hz) connectivity increased compared to nonlucid REM sleep. During eye signaling of lucidity, gamma1 power (30-36 Hz) increased in right temporo-occipital regions, including the precuneus, and interhemispheric gamma1 connectivity rose. These patterns suggest shifts in network communication underlying changes in perception, self-awareness, and cognitive control.

Electrophysiological correlates of lucid dreaming: sensor and source level signatures

bioRxiv Preprint Server April 9, 2024 Çağatay Demirel, Jarrod Gott, Kristoffer Appel et al. 2 citations preprint

Lucid dreaming, a state of conscious awareness during REM sleep, is associated with specific brain activity patterns. Compared to non-lucid REM sleep, EEG sensor-level differences were few. However, source-level analysis revealed increased gamma1 power (30-36 Hz) in left-hemispheric temporal areas during lucid dreaming, potentially reflecting verbal insight processes, and in right temporo-occipital regions including the precuneus around the onset of lucid eye signaling, linked to self-referential thinking. Beta power (12-30 Hz) decreased in right central and parietal areas including the temporo-parietal junction, possibly related to conscious reality assessment. Alpha-band (8-12 Hz) functional connectivity increased, contrasting with psychedelic states and highlighting enhanced self-awareness.