Proceedings of The Physiological Society

Sleep Sleep and Circadian Rhythms (London, UK) (2018) Proc Physiol Soc 42, SA17

Research Symposium

REM sleep in blind people

J. A. Christensen1,2, S. Aubin3,4,5, T. Nielsen6, M. Ptito4,5,7, R. Kupers4,8, P. J. Jennum1

1. Danish Center for Sleep Medicine, Rigshospitaet, Glostrup, Glostrup, Denmark. 2. Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark. 3. Department of Neuroscience, University of Montreal, Montreal, Quebec, Canada. 4. Brain Research and Integrative Neuroscience Laboratory, Danish Center for Sleep Medicine, Rigshospitalet, Glostrup, Denmark. 5. Harland Sanders Chair in Visual Science, School of Optometry, University of Montreal, Montreal, Quebec, Canada. 6. Dream and Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, Department of Psychiatry, University of Montreal, Montreal, Quebec, Canada. 7. Laboratory of Neuropsychiatry and Psychiatric Centre Copenhagen, University of Copenhagen, Copenhagen, Denmark. 8. Department of Radiology & Biomedical Imaging, Yale University, New Haven, Connecticut, United States.

Abstract Body : Study objectives: There is an ongoing controversy regarding the role of rapid eye movements (EMs) during REM sleep. One prevailing hypothesis is that EMs during REM sleep are indicative of the presence of visual imagery in dreams. Congenital blindness appears as a good model to test empirically the validity of this claim since congenitally blind (CB) individuals never developed a visual repertoire. We therefore tested the validity of the scanning of visual dreams hypothesis by measuring EMs in CB individuals, individuals that became blind later in life (LB) and sighted controls (SC) and correlated these with visual dream content. Methods: Eleven blind, of whom 5 were blind from birth (CB; 40.8±16.1 years of age) and 6 that became blind later in life (LB; 47.5±14.7 years of age) and 11 matched sighted control (SC; 43.9±14.8 years of age) subjects participated in this study. The Blindness Duration Index (BDI), calculated as the duration of blindness over age, represents the relative amount of time a subject has been blind, where high scores indicate that they have been blind for the majority of their life, and low scores indicate a recent onset of blindness. All participants underwent full-night polysomnography (PSG) recordings staged manually following American Academy of Sleep Medicine (AASM) scoring criteria. Periods with any kind of EMs were detected automatically by using a validated EM detector, and the EM coverage was measured as the percentage of time containing EMs, during wakefulness, N1, N2, N3 and REM sleep. Frequency of sensory dream elements was measured in dream recall questionnaires over a 30-day period. Results: Both blind groups showed a lower EM coverage during wakefulness, N1, N2 and REM sleep than did controls. CB and LB participants did not differ in EM coverage. Post-validation of the detector applied to blind subjects revealed an overall accuracy of 95.6±3.6%. There were no significant correlations between the incidence of nocturnal EMs and BDI. Analysis of dream reports revealed that CB participants reported very few or no visual dream elements, which was significantly lower as compared to both LB and SC participants. Conclusions: We found dissociation between EMs and visual dream content in the two groups of blind participants. The quasi absence of nocturnal EMs in LB individuals despite preserved visual dream content does not support the visual scanning of dreams hypothesis. It might be argued that extended blindness in LB has led to an uncoupling of EMs from visual dream content.

Where applicable, experiments conform with Society ethical requirements