Two Distinct Synchronization Processes in the Transition to Sleep: A High-Density Electroencephalographic Study

• DOI: 10.5665/sleep.4070
• Publication Date: 2014-09-30T19:59:56Z
• Authors: Francesca Siclari; Giulio Bernardi; Brady A. Riedner; Joshua J. LaRocque; Ruth M. Benca; Giulio Tononi
• Keywords: Sleep spindle; Falling (accident); Sleep

To assess how the characteristics of slow waves and spindles change in falling-asleep process. Participants undergoing overnight high-density electroencephalographic recordings were awakened at 15- to 30-min intervals. One hundred forty-one periods analyzed scalp source level. Sleep laboratory. Six healthy participants. Serial awakenings. The number amplitude followed two dissociated, intersecting courses during transition sleep: wave increased slowly beginning rapidly end period, whereas first then decreased linearly. Most occurring early sleep had a large amplitude, steep slope, involved broad regions cortex, predominated over frontomedial regions, preferentially originated from sensorimotor posteromedial parietal cortex. later smaller more circumscribed parts evenly distributed origins. Spindles initially sparse, fast, few cortical became numerous slower, areas. Our results provide evidence for types waves, which follow dissociated temporal have distinct origins distributions. We hypothesize that these result synchronization processes: (1) "bottom-up," subcorticocortical, arousal system-dependent process predominates phase leads type I (2) "horizontal," corticocortical late II waves. dissociation between processes time space suggests they may be differentially affected by experimental manipulations disorders.