Human brain pulsations during sleep

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Auditorium 7, Oulu University Hospital, Kajaanintie 50

Topic of the dissertation

Human brain pulsations during sleep

Doctoral candidate

Master in Health Sciences (MHSci) Heta Helakari

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Research Unit of Health Sciences and Technology

Subject of study

Medical Physics and Technology


Professor Sari-Leena Himanen, Tampere University


Professor Vesa Kiviniemi, University of Oulu

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Brain pulsations that drive the brain clearance change during light sleep

Studies have shown that brain clearance accelerates especially during deep sleep. In addition, especially cardiovascular pulsations seem to drive the clearance, but also breathing and slow vasomotion of blood vessels seem to have a role. In this study, we studied these three pulsations during awake and sleep in healthy subjects.
We studied the pulsations by using fast functional magnetic resonance imaging together with electroencephalography (EEG) and respiratory and cardiovascular measures. We analysed strength, speed, direction and stability of the pulsations.
All three brain pulsations intensified during light N1-2 sleep, and slow vasomotion and respiratory pulsations also fastened. N2 sleep, deeper than N1 drowsiness, affected to larger brain regions, stabilized the respiratory pulsation in whole brain and promoted CSF pulsation. Falling asleep after one night sleep deprivation intensified vasomotor pulsations. Pulsation changes occurred in same brain regions with increased slow delta power, supporting the previous literature.
This study reveals that brain pulsations have a meaningful role in accelerating the brain clearance. The current research gives new insights about brain functions during sleep and may serve a background to further diagnostics and precenting bran diseases.
Last updated: 20.5.2024