Reversed and increased functional connectivity in non-REM sleep suggests an altered rather than reduced state of consciousness relative to wake.
Scientific reports June 7, 2021 Evan Houldin, Zhuo Fang, Laura B Ray et al. 17 citations
During sleep, functional connections between brain networks shift in a directional manner. In non-REM (NREM) sleep, positive wake-like correlations often become negative and strengthen in the opposite direction, while in REM sleep they trend back toward positive correlations. This pattern supports the idea that NREM sleep involves altered, not merely reduced, functional connectivity. Many of these connections involve higher-order networks linked to cognition and consciousness, such as the default mode network, suggesting possible accompanying changes in cognitive and conscious states.