Original ArticleThe sensory construction of dreams and nightmare frequency in congenitally blind and late blind individuals

- Dream content analysis in 11 congenitally blind (CB), 14 late blind (LB) and 25 sighted controls (SC).
- CB and LB subjects have fewer visual dream impressions than SC.
- Blindness duration correlates negatively with duration of visual dream impressions in LB.
- CB report more auditory, tactile, gustatory and olfactory dream components compared to SC.
- CB subjects report more nightmares compared to LB and SC.

ObjectivesWe aimed to assess dream content in groups of congenitally blind (CB), late blind (LB), and age- and sex-matched sighted control (SC) participants.MethodsWe conducted an observational study of 11 CB, 14 LB, and 25 SC participants and collected dream reports over a 4-week period. Every morning participants filled in a questionnaire related to the sensory construction of the dream, its emotional and thematic content, and the possible occurrence of nightmares. We also assessed participants' ability of visual imagery during waking cognition, sleep quality, and depression and anxiety levels.ResultsAll blind participants had fewer visual dream impressions compared to SC participants. In LB participants, duration of blindness was negatively correlated with duration, clarity, and color content of visual dream impressions. CB participants reported more auditory, tactile, gustatory, and olfactory dream components compared to SC participants. In contrast, LB participants only reported more tactile dream impressions. Blind and SC participants did not differ with respect to emotional and thematic dream content. However, CB participants reported more aggressive interactions and more nightmares compared to the other two groups.ConclusionsOur data show that blindness considerably alters the sensory composition of dreams and that onset and duration of blindness plays an important role. The increased occurrence of nightmares in CB participants may be related to a higher number of threatening experiences in daily life in this group.