During the transition from wake to sleep, the human brain exhibits progressive, regional, and frequency-specific electroencephalographic (EEG) changes, mainly represented by (a) an increase of the slowest frequencies (≤ 7 Hz) with an anteroposterior gradient; (b) a shift from a posterior to an anterior dominance of alpha activity (8–12 Hz); (c) an increase in the sigma frequency range (~ 12–15 Hz), denoting the emergence of sleep spindles; and (d) a generalized reduction of the highest frequency activity (16–40 Hz). Moreover, several subcortical structures show sleep-like rhythms before the cortically defined sleep onset. Also, the dynamics of the interactions between cortical areas are characterized by progressive modifications during the wake-sleep transition. According to these findings, sleep onset should not be considered a global and unitary phenomenon, but a complex local and progressive process, during which sleep-like and wake-like EEG patterns coexist. Several peculiar phenomena often observed at sleep onset (hypnagogic hallucinations, sleep misperception, and mesograde amnesia) may be explained by such spatiotemporal asynchronies.

Timing and Topography of Sleep Onset: Asynchronies and Regional Changes of Brain Activity

D'Atri A.;Ferrara M.;De Gennaro L.
2019

Abstract

During the transition from wake to sleep, the human brain exhibits progressive, regional, and frequency-specific electroencephalographic (EEG) changes, mainly represented by (a) an increase of the slowest frequencies (≤ 7 Hz) with an anteroposterior gradient; (b) a shift from a posterior to an anterior dominance of alpha activity (8–12 Hz); (c) an increase in the sigma frequency range (~ 12–15 Hz), denoting the emergence of sleep spindles; and (d) a generalized reduction of the highest frequency activity (16–40 Hz). Moreover, several subcortical structures show sleep-like rhythms before the cortically defined sleep onset. Also, the dynamics of the interactions between cortical areas are characterized by progressive modifications during the wake-sleep transition. According to these findings, sleep onset should not be considered a global and unitary phenomenon, but a complex local and progressive process, during which sleep-like and wake-like EEG patterns coexist. Several peculiar phenomena often observed at sleep onset (hypnagogic hallucinations, sleep misperception, and mesograde amnesia) may be explained by such spatiotemporal asynchronies.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/141229
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