Biology subjects

Erlacher, D.

Publications and source records attributed to Erlacher, D..

6 recordsLinked to original sources

bioRxiv2026

Balancing Lucidity: Muscle and Vestibular Stimulation for Lucid Dream Induction

Lucid dream (LD) induction using external sensory stimulation has most commonly relied on distal cues such as lights or auditory signals, with mixed success rates. In this study, we investigated whether more direct bodily stimulation targeting the muscle and vestibular systems could influence LD induction. We compared electrical muscle stimulation (EMS) and galvanic vestibular stimulation (GVS), each combined with a two-week cognitive training protocol including dream journaling, reality checks, and association training. Twenty-eight participants (14 per group) completed two counterbalanced morning naps: one with stimulation (STIM) during REM sleep and with one sham-stimulation control (SHAM). EMS and GVS stimulation did not lead to increased incorporation of the stimulus. Lucidity rates were high in both EMS conditions, highlighting the substantial role of elevated baseline lucidity in induction studies, cognitive training, and expectation effects. In contrast, GVS stimulation significantly increased externally rated lucidity and DLQ questionnaire scores compared to control. Overall, the findings indicate that galvanic vestibular stimulation can increase dream lucidity. Future work should further examine the mechanisms by which vestibular stimulation influences dream awareness and its potential role in lucid dream induction. O_FIG O_LINKSMALLFIG WIDTH=191 HEIGHT=200 SRC="FIGDIR/small/711028v1_ufig1.gif" ALT="Figure 1"> View larger version (86K): org.highwire.dtl.DTLVardef@7de78forg.highwire.dtl.DTLVardef@1ed7628org.highwire.dtl.DTLVardef@e84964org.highwire.dtl.DTLVardef@2a5f5e_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2026

Waking Up in the Dream Lab: A Lab-Based Lucid Dream Induction Paradigm Using Virtual Reality and Sensory Stimulation

Lucid dreaming (LD), during which the dreamer is aware that they are dreaming, is frequently induced in laboratory settings by delivering sensory cues during rapid eye movement (REM) sleep. These cues should be incorporated into ongoing dreams and can trigger reflective awareness. This approach relies on the continuity between waking experiences and dream content. In sleep laboratories, participants often dream of the experimental setting itself (lab dreaming), providing a predictable context in which lucidity may emerge. The present studies leveraged this phenomenon by explicitly training participants to associate the sleep laboratory with reflective awareness prior to sleep. Across three studies (total N = 101), participants completed a morning nap following verbal LD instructions and presleep audio designed to prime recognition of the laboratory context in dreams. In addition, conditions included immersive virtual reality (VR) rehearsal of the laboratory environment, VR combined with haptic stimulation (HS) during REM sleep, or VR containing subtle fake system errors intended to prompt reflective checking. LD frequency was assessed through external ratings of signal-verified LD (SVLD) dream reports. Lucidity rates were high across all conditions, with approximately 40-45% of dreams externally rated as lucid and 11%-32% SVLDs occurring in every group. However, neither VR rehearsal, haptic stimulation, nor implicit VR errors increased lucidity relative to the baseline laboratory induction procedure. Exploratory analyses investigated the overlap between laboratory dreaming, false awakenings (FAs), and lucidity. These findings suggest that explicit training focused on the predictable context of the sleep laboratory may already provide a powerful pathway to lucidity, with additional technological manipulations offering limited benefit under a single-nap protocol. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/711049v2_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@8f2327org.highwire.dtl.DTLVardef@14cfbaeorg.highwire.dtl.DTLVardef@11f9bbforg.highwire.dtl.DTLVardef@2a57bf_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

EEG Microstates reveal distinct network dynamics in lucid and non-lucid REM sleep

During lucid dreaming, the dreamer is aware that they are dreaming. In past years, numerous studies have explored the characteristics of lucid dreams, which link lucid dreams to vivid visual perception, positive emotions, and wake-like metacognition and executive functions. To determine brain network activity associated with the conscious experience during lucid dreaming, we analyzed 39 sleep recordings (non-lucid REM vs. lucid REM) with 32-channel polysomnography from 8 lucid dreamers, using EEG microstate analysis. We found that microstates A and G dominated during lucid REM sleep compared to non-lucid REM sleep, and microstates B, C, and D dominated during non-lucid REM sleep compared to lucid REM sleep. We explored the correlation of our microstate maps with previous findings based on topographical similarities of the microstate maps in our study. This suggests that in our study, microstate A might be associated with emotional processing, microstate B with visual processing, microstate C with salience network activity, microstate D with executive functions, and microstate G with the default mode network. Our results suggest that lucidity during REM sleep is associated with increased self-visualization, metacognition, and executive processing, along with decreased emotional processing and reduced default mode network activity. Additionally, we found the inverse relationship between the presence of microstates/networks associated with regions that serve specific functions and evidence for the function being used. This might indicate the inhibitory function of the EEG microstates during sleep. Our study provides novel insight into the distinct network dynamics in lucid and non-Lucid REM sleep.

neuroscience↗

bioRxiv2025

Juggling the Limits of Lucidity: Searching for Cognitive Constraints in Dream Motor Practice

Lucid dreaming (LD), during which the dreamer becomes aware of the dream state, offers a unique opportunity for a variety of applications, including motor practice, personal well-being, and nightmare therapy. However, these applications largely depend on a dreamers ability to control their dreams. While LD research has traditionally focused on induction techniques to increase dream frequency, the equally crucial skill of dream control remains underexplored. This study provides an initial investigation into the mechanisms of dream control and its potential influencing factors. We specifically examined whether a complex motor skill--juggling--could be performed within a lucid dream, creating a particularly challenging lucid dream task, which calls for a high level of dream control. Eight healthy participants (aged 24-50) underwent overnight polysomnography (PSG) at the University of Berns Institute for Sports Science, provided detailed dream reports, and completed questionnaires assessing dream control, self-efficacy, personality traits, mindfulness, motivation, and intention setting. Of these, four participants experienced lucid dreams, and of these, two demonstrated high dream control with successful LD juggling attempts. Trait differences between non-lucid and lucid dreamers in the lab were examined, with a focus on low-to-no dream control versus high dream control among the lucid dreamers. The two lucid dream juggling attempts are described in detail, providing insight into the challenges of executing complex tasks within a lucid dream. While this study lacks in sample size, it highlights the potential roles of many psychological traits, such as belief, motivation, and self-efficacy, in shaping dream control abilities. This study helps to lay the groundwork for future research aimed at investigating lucid dream control and therefore optimizing LD applications in therapy, sports training, and cognitive science.

neuroscience↗

bioRxiv2024

A Comparative Study of Muscular, Vestibular, and Haptic Stimulation on Dream Incorporation

The connection between the dreamed body and the real physical body remains a subject of ongoing investigation. This study explored how the dreamed body responds to somatosensory stimulation of the physical body, aiming to shed light on the sensory processes that shape our dreaming experiences. We employed a novel within-subject design to compare the incorporation of three different types of bodily stimuli--electrical muscular, galvanic vestibular, and haptic vibration--into dream content, alongside a control sham condition for each stimulus. In total, 24 participants spent one adaptation night, followed by three consecutive test nights in the sleep laboratory. REM awakenings, after sham or stimulation periods, were carried out for dream report collection. In total, 165 dream reports were collected across conditions. While dream incorporation was observed across the three stimulation methods, it occurred equally in both the stimulation and sham conditions for all three modalities. These findings highlight broader methodological challenges in dream incorporation research and raise concerns about potential confounding factors affecting the interpretation of results. Future research with larger sample sizes is needed to detect smaller effect sizes and fully understand the influence of these somatosensory stimuli on dream content. This study employed a rigorous experimental approach to exploring dream incorporation and addressed many methodological challenges in this area. We further suggest areas of improvement to optimize dream incorporation of different sensory modalities. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=164 SRC="FIGDIR/small/626974v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@19dd9cdorg.highwire.dtl.DTLVardef@462ac4org.highwire.dtl.DTLVardef@a1b33borg.highwire.dtl.DTLVardef@1fe0596_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

The number of effectors limits the relative sleep gain: Insights from seven finger tapping experiments

The role of sleep in motor memory consolidation is still a matter of ongoing debate. A classic task to investigate mechanisms of motor memory consolidation is the finger tapping task, which reliably shows small effects in performance enhancement after sleep but not after a corresponding wake interval. However, variants of the task with a varying number of effectors (e.g., one hand) failed to demonstrate this effect on motor memory consolidation. Thus, in a series of seven experiments we investigate five variants of the classic finger tapping task in which the number of effectors (1 or 2 hands combined with 1, 2 or 4 fingers) used to perform the task are systematically varied. For the groups, where sleep immediately followed learning, a beneficial effect of sleep in comparison with a corresponding wake interval was found, except for the task variant where the finger tapping task was performed with 1 hand and 1 finger. However, no clear-cut pattern could be identified for the numbers of effectors used to perform the task and the magnitude of offline motor memory consolidation. Furthermore, for groups with an intervening wake interval between learning and sleep no differences between the post-sleep and post-wake gain were observed. HighlightsIn a variation of the classical finger tapping task with one hand and one finger, no sleep-dependent enhancement was found. In all other variations, small to large effects of sleep-dependent offline-gains were found. An interposed wake interval between learning and sleep substantially diminishes the post-sleep enhancement. Motor skill complexity, with respect to the coordination of more than one effector, does partially play a role in predicting sleep-dependent motor memory enhancement.

neuroscience↗