EEG Recordings Suggest Brain Prioritizes Internal Sensory Information During REM Sleep

Sensory Processing During REM Sleep

Research from the universities of Lausanne and Geneva indicates that the brain's processing of sensory information changes significantly during REM sleep. While external signals from the environment diminish, signals originating from the body itself are maintained or even amplified. This suggests a shift in sensory prioritization during this sleep stage.

Study Findings and Publication

The findings, published in Current Biology, detail how the brain progressively reorganizes its sensory information processing from wakefulness to REM sleep. The team, led by Marzia De Lucia and in collaboration with Sophie Schwartz, utilized EEG recordings to observe these changes in brain activity.

Disconnecting Without Unplugging

Neuroscientists have long sought to understand how the brain sorts and prioritizes sensory information, especially during different states of consciousness. REM sleep offers a unique context for this inquiry, as it involves a profound disconnection from the external world despite neural activity sharing similarities with the awake brain. This disconnection is characterized by a higher arousal threshold, meaning external stimuli are less likely to reach conscious processing.

Gradual Transition in REM Phases

REM sleep is not a uniform state but alternates between tonic REM and phasic REM. Phasic REM is marked by rapid eye movements, brief muscle twitches, and variable heart and respiratory rhythms. The study leveraged the known gradual decrease in sensitivity to external stimuli from wakefulness to tonic REM and then to phasic REM, where it reaches its lowest point, to compare sensory processing across these stages.