Motivation: The accumulation of amyloid-beta (Aβ) plaques is a key factor in Alzheimer's Disease pathogenesis. Animal studies indicate that reduced cerebrospinal fluid (CSF) clearance may impair the removal of these neurotoxic proteins by 40-70%, while sleep can double clearance efficiency due to an increase in extracellular space. Goal(s): To determine the impact of sleep on extracellular space in humans. Approach: We investigated changes in extracellular volume fraction (ECVF) across sleep stages using simultaneous sodium MRI and electroencephalography (EEG). Results: A significant decrease in ECVF was observed in gray matter regions of the brain during non-rapid eye movement (NREM) stage 3 sleep. Impact: Our findings confirmed the impact of sleep on extracellular volume fraction in the human brain, which may influence cerebrospinal fluid clearance and has potential implications for Alzheimer's Disease progression.
Watson et al. (Tue,) studied this question.