Dream content after using visual inverting prisms.

All night sleep electroencephalograms were recorded in 10 healthy adults for 2 nights. On the second night all subjects were requested to be at the laboratory 5 hr. before their usual bedtime and were submitted to the same routine for performance on several visuomotor tasks; experimental subjects were required to use visual inverting prisms upon their arrival and during the performance of the tasks. Subjects were awakened 10 min. after each paradoxical sleep episode for dream collection. Dream content was significantly affected by the use of the inverting prisms: the presleep tasks and day-time activities were more frequently incorporated into the dreams of the experimental subjects. The dreams of the experimental group were more active and vividness was evaluated as lower by them than by the control subjects.