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Sensory processing reallocation from auditory to cardiac signals in REM sleep
Jacinthe Cataldi1, Andria Pelentritou1, Sophie Schwartz2
1Brain-Body and Consciousness Laboratory, Department of Clinical Neurosciences, Lausanne University Hospital, University of Lausanne, Chemin de Mont-Paisible 16, 1011 Lausanne, Switzerland.
Current Biology : CB
|August 3, 2026
Summary
The brain prioritizes internal bodily signals over external ones during REM sleep. This shift in sensory processing, from auditory to cardiac, offers insights into altered consciousness.
Area of Science:
- Neuroscience
- Sleep Science
- Cognitive Psychology
Background:
- The brain integrates external (exteroception) and internal (interoception) information.
- How this balance shifts across vigilance states, especially during sleep, is unclear.
Purpose of the Study:
- To investigate neural processing of auditory and cardiac signals across wakefulness and REM sleep microstates.
- To determine how the exteroceptive-interoceptive balance changes with decreasing environmental responsiveness.
Main Methods:
- High-density electroencephalography (EEG) in 25 healthy participants.
- Measured auditory evoked potentials (AEPs) and heartbeat evoked potentials (HEPs) during wakefulness, tonic REM, and phasic REM.
- Calculated an audio-cardio index (ACI) to quantify sensory weighting.
Main Results:
- Auditory evoked potentials (AEPs) decreased significantly from wakefulness to phasic REM.
- Heartbeat evoked potentials (HEPs) were preserved and enhanced during REM sleep compared to wakefulness.
- The audio-cardio index (ACI) decreased across vigilance states, indicating a shift towards interoception.
Conclusions:
- During REM sleep, particularly phasic REM, the brain shifts processing from external auditory stimuli to internal cardiac signals.
- This altered exteroceptive-interoceptive balance may serve as a marker for changes in consciousness, even without behavioral response.
- The findings highlight the brain's continued prioritization of vital internal signals during reduced environmental engagement.
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