Simultaneous stomach-brain electrophysiology reveals dynamic coupling in human sleep
Sleep involves coordinated interactions between the brain and body, yet whether and how peripheral physiology is organized during human sleep is poorly understood. Because gastric rhythms are strongly modulated by arousal states during wakefulness, we hypothesized that gastric electrical rhythms exhibit structured dynamics aligned with cortical oscillations during sleep. Using simultaneous high-density electroencephalography and electrogastrography, we find that gastric activity persists throughout sleep, increases during non-rapid eye movement (NREM), and exhibits infraslow fluctuations that are amplified during NREM. Moreover, gastric activity is synchronized with slow oscillations and sleep spindles, with gastric power tracking spindle occurrence and cortical infraslow cycles. Stomach-brain coupling predicted next-day memory recall beyond cortical measures, whereas gastric infraslow dynamics predicted subjective sleep quality beyond polysomnographic measures. Together, our findings show that even as the brain disconnects from the external world, it maintains structured communication with peripheral organs, reframing sleep as a coordinated, multi-organ physiological state.