bioRxiv ScienceSearch

Biology subjects

Olsen, M. H.

Publications and source records attributed to Olsen, M. H..

2 recordsLinked to original sources

Prevalence of near-death experiences and REM sleep intrusion in 1034 adults from 35 countries

BackgroundNear-death experiences have fascinated humans for centuries, but their origin and prevalence remain unknown. MethodsUsing an online crowdsourcing platform, we recruited 1034 lay people from 35 countries to investigate the prevalence of near-death experiences and self-reported REM sleep intrusion. Reports were validated using the Greyson Near-Death Experiences Scale (GNDES) with a score of [&ge;]7 as cut-off point for identifying near-death experiences. ResultsNear-death experiences were reported by 106 of 1034 participants (10%; CI 95% 8.5-12%). REM sleep intrusion was more common in people with near-death experiences (n=50/106; 47%) than in people with experiences with 6 points or less on the GNDES (n=47/183; 26%) or in those without any such experience (n=107/744; 14%; p=<0.0001). Following multivariate regression analysis to adjust for age, gender, place of origin, employment status and perceived danger, this association remained highly significant; people with REM sleep intrusion were more likely to exhibit near-death experiences than those without REM sleep abnormalities (odds ratio 2.85; CI 95% 1.68-4.88; p=0.0001). ConclusionsThe prevalence of near-death experiences in the public is around 10%. While age, gender, place of residence, employment status and perceived threat do not seem to influence the prevalence of near-death experiences, there is a significant association with REM sleep intrusion. This finding is in line with the view that despite imminent threat to life, brain physiology must be well-preserved to perceive these fascinating experiences and store them as long-term memories.

neuroscience

Automated Pupillometry to Detect Command Following in Neurological Patients: A Proof-of-Concept Study

AbstractO_ST_ABSBackgroundC_ST_ABSLevels of consciousness in patients with acute and chronic brain injury are notoriously underestimated. Paradigms based on electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) may detect covert consciousness in unresponsive patients but are subject to logistical challenges and the need for advanced statistical analysis.\n\nMethodsTo assess the feasibility of automated pupillometry for the detection of command following, we enrolled 20 healthy volunteers and 48 patients with a wide range of neurological disorders, including 7 patients in the intensive care unit (ICU), who were asked to engage in mental arithmetic.\n\nResultsFourteen of 20 (70%) healthy volunteers and 17 of 43 (39.5%) neurological patients, including 1 in the ICU, fulfilled prespecified criteria for command following by showing pupillary dilations during [&ge;]4 of 5 arithmetic tasks. None of the 5 sedated and unconscious ICU patients passed this threshold.\n\nConclusionsAutomated pupillometry combined with mental arithmetic appears to be a promising paradigm for the detection of covert consciousness in people with brain injury. We plan to build on this study by focusing on non-communicating ICU patients in whom the level of consciousness is unknown. If some of these patients show reproducible pupillary dilation during mental arithmetic, this would suggest that the present paradigm can reveal conscious awareness in unresponsive patients in whom standard investigations have failed to detect signs of covert consciousness.

neuroscience