Human parahippocampal activity: non-REM and REM elements in wake-sleep transition.
Brain Research Bulletin March 15, 2005 Róbert Bódizs, Melinda Sverteczki, Alpár Sándor Lázár et al.
The covert-rapid-eye-movement (REM) sleep hypothesis of dreaming suggests that elements of REM sleep emerge during sleep onset, leading to vivid hypnagogic imagery. Based on parahippocampal electrocorticography of epileptic patients we found an increase in REM-like 1.5-3.0 Hz parahippocampal activity during wake-sleep transition, which peaks after on average 30s of sleep onset, and reaches 82%...