Scientific Reports
January 15, 2014
Natália Bezerra Mota, Raimundo Furtado, Pedro Maia et al.
159 citations
Analyzing speech graphs from dream reports can distinguish people with schizophrenia from those with bipolar disorder and non-psychotic controls. People with schizophrenia showed reduced speech connectivity in both waking and dream reports, which correlated with negative and cognitive symptoms. People with bipolar disorder were indistinguishable from controls in waking reports but showed significantly less connectivity in dream reports. Dream-related speech graph attributes outperformed psychometric scores and waking data for sorting groups. The findings suggest that dreaming exposes differences in memory processing across individuals while waking dampens distinctions, and point toward a fast, low-cost, language-invariant tool for psychiatric diagnosis.
PLoS One
November 30, 2020
Natália Bezerra Mota, Janaína Weissheimer, Marina Ribeiro et al.
71 citations
Dreams during the 2019-20 coronavirus outbreak reveal psychological distress. Analyzing 239 dream reports from 67 individuals, dreams during the Coronavirus disease 2019 (COVID-19) Pandemic showed more anger and sadness words. These dreams also linked to "contamination" and "cleanness." Intriguingly, these dream characteristics explained 40% of the variation in psychological suffering related to social isolation, relevant for Psychiatry and Medicine. This underscores how the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) crisis impacts Sleep and Wakefulness Research, including mind wandering and attention, reflecting widespread Coronavirus Infections' effects.
PLoS One
July 23, 2020
Joshua M. Martin, Danyal Wainstein Andriano, Natália Bezerra Mota et al.
41 citations
Dream reports collected after rapid eye movement (REM) sleep are typically longer, more vivid, and more story-like than those from non-REM sleep, but traditional measures may be confounded by report length. By analyzing 133 dream reports from 20 participants as non-semantic directed word graphs, researchers found that REM dream reports have greater connectedness—words recur with longer range—compared to N2 sleep reports. Graph measures predicted dream complexity, with higher connectedness and lower randomness linked to more complex reports. The largest connected component improved models using report length alone for predicting sleep stage and complexity. Graph analysis offers an automated method to complement traditional dream report analysis.
Psychopharmacology
June 1, 2022
Isabel Wießner, Marcelo Falchi, Fernanda Palhano-Fontes et al.
22 citations
LSD alters the stream of thought in multiple ways, increasing chaos, meaning, and abstractness at different times after ingestion. In a randomized, double-blind, placebo-controlled crossover study with 24 healthy participants, 50 μg LSD compared to placebo induced facets of mind-wandering labeled 'chaos' (discontinuity of mind, decreased sleepiness and planning), 'meaning' (deep thoughts), and 'sensation' (thoughts about odors and sounds). LSD also increased free association for abstract words, reflecting an 'abstract flow.' Chaos was strongest from 2 to 6 hours after dosing, meaning from 2 to 4 hours, sensation at 2 hours, and abstract flow at 4 hours. The findings suggest a late therapeutic window around 4 hours for psycholytic therapy.
medRxiv
May 21, 2020
Natália Bezerra Mota, Janaína Weissheimer, Marina Ribeiro et al.
7 citations
preprint
Dreams during the COVID-19 pandemic contained a higher proportion of anger and sadness words and were semantically more similar to the terms contamination and cleanness compared to dreams from before the outbreak. These dream features were associated with mental suffering related to social isolation, explaining 39% of the variance in negative symptoms measured by the PANSS scale. The findings suggest that pandemic dreams reflect mental suffering, fear of contagion, and changes in daily habits.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology
March 1, 2023
Isabel Wießner, Marcelo Falchi, Dimitri Daldegan-Bueno et al.
6 citations
Low to moderate doses of LSD alter language structure, semantics, and vocabulary over time. In a double-blind, placebo-controlled crossover study, 24 healthy volunteers (age 35±11, 33% women) received 50 μg LSD or placebo. LSD reduced verbosity, lexicon, and connectivity in speech networks from 1.5 to 4 hours, decreased semantic distances between words from 2 to 24 hours, and shifted vocabulary related to grammar, persons, time, space, and biological processes from 1.5 to 24 hours. Simpler, disconnected structure and increased semantic similarity may reflect cognitive impairments, while vocabulary changes may indicate subjective perceptual shifts. Automated language analysis could offer unconstrained insights into psychedelic cognition.
Neuroimage
October 17, 2022
Natália Bezerra Mota, Ernesto Soares, Edgar Altszyler et al.
5 citations
Visual and emotional aspects of waking memories follow different paths as people fall asleep. Healthy adults viewed an emotional image, then were awakened seconds to minutes later during wakefulness, N1, or N2 sleep stages. Semantic similarity between the image and subsequent hypnagogic imagery—the 'image residue'—persisted and even increased during N1 sleep, lasting longer with more time in that stage. In contrast, the emotional tone of the image—the 'affect residue'—gradually faded as sleep progressed, becoming neutralized and reaching its lowest point during N2. Brain theta power (4.5–6.5 Hz) during N1 was inversely related to image residue. These findings suggest that visual content and strong negative emotions may decouple at sleep onset, possibly aiding emotional processing.
Scientific Reports
March 13, 2026
Daniel Soares Brandão, Rafael N. B. Scott, Ernesto Soares et al.
Slow wave activity during a nap and dreams related to a stressful video game predict better post-sleep performance for people in a low-agency, prey-like role, but not for those in a high-agency predator role. Thirty adult pairs played a first-person shooter game against each other, then napped while EEG and ECG were recorded, reported dreams, and played again. For participants assigned the prey role, score improvements correlated positively with slow wave activity during the nap, how much dreams related to the game, and heart rate variability during the first round. No such correlations appeared for predator-role participants, suggesting sleep's adaptive function may be especially important for individuals facing threatening, low-control situations.
Schizophrenia Research
October 20, 2025
Elena Camon, Stefano Masier, Natália Bezerra Mota et al.
Language disorganization in psychosis can be objectively measured by analyzing speech as a network. This study examined written and oral dream reports from 193 Italian participants (115 with acute psychosis and 78 healthy controls), constructing structural speech graphs and measuring connectivity attributes like the Largest Connected Component and its z-score relative to random graphs. Patients with psychosis showed significantly lower connectivity values than controls, with their speech graphs more closely resembling random word sequences. These differences remained after controlling for education and survived statistical correction. A Naive Bayes classifier using these features achieved 68% accuracy (AUC = 0.75), supporting automated detection. This work reinforces the cross-linguistic validity of graph-based analysis of thought and language impairments in psychosis.