AUTHOR=Helakari Heta , Järvelä Matti , Väyrynen Tommi , Tuunanen Johanna , Piispala Johanna , Kallio Mika , Ebrahimi Seyed Mohsen , Poltojainen Valter , Kananen Janne , Elabasy Ahmed , Huotari Niko , Raitamaa Lauri , Tuovinen Timo , Korhonen Vesa , Nedergaard Maiken , Kiviniemi Vesa TITLE=Effect of sleep deprivation and NREM sleep stage on physiological brain pulsations JOURNAL=Frontiers in Neuroscience VOLUME=17 YEAR=2023 URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1275184 DOI=10.3389/fnins.2023.1275184 ISSN=1662-453X ABSTRACT=Introduction

Sleep increases brain fluid transport and the power of pulsations driving the fluids. We investigated how sleep deprivation or electrophysiologically different stages of non-rapid-eye-movement (NREM) sleep affect the human brain pulsations.

Methods

Fast functional magnetic resonance imaging (fMRI) was performed in healthy subjects (n = 23) with synchronous electroencephalography (EEG), that was used to verify arousal states (awake, N1 and N2 sleep). Cardiorespiratory rates were verified with physiological monitoring. Spectral power analysis assessed the strength, and spectral entropy assessed the stability of the pulsations.

Results

In N1 sleep, the power of vasomotor (VLF < 0.1 Hz), but not cardiorespiratory pulsations, intensified after sleep deprived vs. non-sleep deprived subjects. The power of all three pulsations increased as a function of arousal state (N2 > N1 > awake) encompassing brain tissue in both sleep stages, but extra-axial CSF spaces only in N2 sleep. Spectral entropy of full band and respiratory pulsations decreased most in N2 sleep stage, while cardiac spectral entropy increased in ventricles.

Discussion

In summary, the sleep deprivation and sleep depth, both increase the power and harmonize the spectral content of human brain pulsations.