Standing sentinel during human sleep: Continued evaluation of environmental stimuli in the absence of consciousness

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While it is a well-established finding that subjects' own names (SON) and familiar voices are salient during wakefulness, we here investigated processing of environmental stimuli during sleep including deep N3 and REM sleep. Besides the effects of sleep depth we investigated how sleep-specific EEG patterns (i.e. sleep spindles and slow oscillations [SOs]) relate to stimulus processing. Using 256-channel EEG we studied processing of auditory stimuli by means of event-related oscillatory responses (de-/synchronisation, ERD/ERS) and potentials (ERPs) in N = 17 healthy sleepers. We varied stimulus salience by manipulating subjective (SON vs. unfamiliar name) and paralinguistic emotional relevance (familiar vs. unfamiliar voice, FV/UFV). Results reveal that evaluation of voice familiarity continues during all NREM sleep stages and even REM sleep suggesting a ‘sentinel processing mode’ of the human brain in the absence of wake-like consciousness. Especially UFV stimuli elicit larger responses in a 1–15 Hz range suggesting they continue being salient. Beyond this, we find that sleep spindles and the negative slope of SOs attenuate information processing. However, unlike previously suggested they do not uniformly inhibit information processing, but inhibition seems to be scaled to stimulus salience.
Original languageEnglish
Pages (from-to)638-648
Number of pages11
Publication statusPublished - 2018

Fields of Science and Technology Classification 2012

  • 301 Medical-Theoretical Sciences, Pharmacy


  • Auditory stimulation
  • High-density electroencephalography
  • Sleep
  • Sleep spindles
  • Slow oscillations

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