People with narcolepsy type 1 recalled detailed dream experiences after 75% of naps that included sleep onset REM periods (SOREMPs) and after 25% of naps without REM sleep. Story-grammar analysis showed that dreams from daytime SOREMP naps are organized as hierarchically ordered sequences of events, called dream-stories, which are longer and more complex in the first and fourth SOREMP naps and comparable in structure to dreams from nighttime REM sleep. This similar structural organization suggests that the cognitive processes underlying dreaming are highly, though not uniformly, effective during daytime SOREMP sleep, and investigating these dreams may clarify links between brain physiology and psychological processes in REM dreaming.
People with narcolepsy type 1 (NT1) report dreams after about 80% of naps that begin with REM sleep (SOREMP naps), as often as healthy people report dreams after nighttime REM sleep. However, after NREM naps, NT1 patients report dreams only about 30% of the time, compared to 60% for healthy subjects. This study tested whether the low NREM dream recall in NT1 is due to a failure to generate dreams or a failure to recall them. Seventeen NT1 patients and 25 subjects with excessive daytime sleepiness took multiple daytime naps and reported dreams, white dreams (sense of having dreamed but no content), or no dreams. White dreams were more frequent in NT1 patients (42.86% vs. 17.
In drug-free adults with narcolepsy type 1, successful dream recall after naps is linked to a more activated brain state during both REM and NREM sleep. Using scalp EEG, the study found that recall was associated with lower delta power over centro-parietal areas in both sleep stages, higher beta power in those areas during NREM, and a lower delta/beta ratio across most scalp locations during NREM. These results suggest that a more desynchronized, activated electrophysiological milieu promotes dream recall, and that parietal areas are important not only for generating dream experiences but also for the memory processes that enable recall.