Subjects with different hypnotizability scores exhibit different heartbeat-evoked potentials during sleep

Aim of this study was to measure possible hypnotizability related differences in the amplitude of cortical heartbeat evoked potentials (HEP) measured during nocturnal sleep stages. Polysomnographic EEG recording was performed in subjects with high (highs, n=6), medium (mediums, n=8) and low (lows, n=24) hypnotizability scores. The mean amplitude of the HEPs for each electrode and sleep stage was calculated in the time window from 200 ms to 600 ms after the R peaks. A multivariate ANOVA using hypnotizability as between-subjects factor was performed for each sleep stage. Results showed higher HEPs mean amplitude in mediums and highs with respect to lows in central, parietal and occipital right regions, during N2, N3 and REM sleep stages. We can hypothesize that, during sleep, individuals with medium-to-high hypnotizability maintain a higher responsiveness to interoceptive information - that is greater body awareness - with respect to lows.