During dreams evoked by stimuli of a certain duration, the EEF was studied in healthy subjects and in patients with implanted electrodes (EEG, ESCoG (electrosubcorticogram), unit activity). Estimation of the temporal structure of the dream was made from the verbal account of the subject. In the case of an unformed dream the duration of the dream was shown to be adequately estimated, the EEF and ESCoG patterns to be rather variable, and correlation between the bioelectric activities of different structures to be nearly absent. Apparently, in these cases, only some of the structures participate in the formation of dreams, which accounts for their unstructure, with no disorder of temporal and spatial relationships, is accompanied by certain orderly rhythms, similar EEG and ESCoG patterns, and a high correlation between bioelectric processes occurring in the structures under study. Dreams with a complex structure, with simultaneous action in different aspects and with major overestimation of their duration, are accompanied by polymorphous EEG and ESCoG patterns. Almost no correlation is observed between bioelectric processes in different structures. Apparently these dreams are associated with independent activities in different structures and, in the verbal account, the subject tends to place the events in a certain temporal order which creates the effect of considerable acceleration of the time flow.