Cardiovascular Activity Predominantly Modulates Brain Dynamics in Non‐REM Sleep Transitions

This study explores the brain–heart axis and its directional control dynamics across various sleep stages using electroencephalography and electrocardiogram data from publicly available whole‐night recordings of 50 healthy individuals. Utilizing a validated functional brain–heart interplay (BHI) mathematical model, we identified a decrease in central control over peripheral neural activity regulating heartbeat dynamics during non‐REM sleep. In contrast, an increase in sympathovagal activity influencing cortical function was observed during deep sleep, particularly in Non‐REM3, compared to light sleep and REM phases. These results indicate a dynamic shift in the functional balance of the brain–heart axis and related BHI throughout sleep stages, characterized by predominant central control during wakefulness and enhanced bodily neuro‐cardiac‐autonomic regulation during deep sleep.