EEG Lempel-Ziv complexity varies with sleep stage, but does not seem to track dream experience.
Frontiers in human neuroscience January 1, 2022 Arnfinn Aamodt, André Sevenius Nilsen, Rune Markhus et al. 29 citations
In a follow-up EEG sleep study, brain signal complexity (Lempel-Ziv complexity, LZC) decreased progressively from wakefulness into deeper non-REM sleep. However, within NREM2 sleep, there was no significant difference in LZC between dream and non-dream awakenings, and no correlation between LZC and subjective ratings of dream vividness, diversity, or perceptual quality. The authors failed to reproduce their earlier finding that posterior LZC increased with more perceptual dream experiences. This raises doubts about whether EEG LZC is a reliable marker of richness of experience within the same sleep stage.