Meditation Flushes Your Brain Like Sleep Does
A 2025 PNAS study found that focused-attention meditation changes cerebrospinal fluid flow in patterns that resemble sleep — the brain's primary waste-clearance state.
The Brain's Waste Problem
Your brain produces metabolic waste constantly — byproducts of neural activity that include beta-amyloid and tau proteins. In 2012, Maiken Nedergaard's lab discovered the glymphatic system: a brain-wide network of perivascular channels that uses cerebrospinal fluid to flush these waste products from brain tissue. The critical finding was that this system is most active during sleep, particularly non-REM deep sleep, and largely disengaged during normal wakefulness. A 2013 study in Science by Xie et al. showed that beta-amyloid clearance roughly doubles during sleep compared to wakefulness. Dysfunction of this waste-clearance system has been linked to accumulation of the misfolded proteins associated with Alzheimer's disease, Parkinson's disease, and Huntington's disease.
Can Meditation Activate This System While Awake?
A research team at Vanderbilt University Medical Center asked a direct question: does meditation alter fluid flow in the brain in a manner analogous to sleep? Keating, Vago, et al. (2025), published in the Proceedings of the National Academy of Sciences, used two types of MRI — phase-contrast MRI to measure cerebrospinal fluid flow through the cerebral aqueduct, and BOLD fMRI to assess CSF fluctuations near the skull base — to compare what happens in the brain during focused-attention meditation versus mind-wandering. The study included 50 participants across three groups: 23 experienced meditators with an average of over 3,700 lifetime hours of practice, 14 meditation-naive adults who simply slowed their breathing to match meditator breathing rates, and 13 controls who underwent repeated resting scans.
What the MRI Showed
During 25 minutes of silent focused-attention meditation, absolute CSF flow through the cerebral aqueduct decreased from 4.60 mL/min to 4.17 mL/min (P = 0.005). This reduction was driven specifically by decreased regurgitant (backward) CSF flow — the retrograde flow that occurs during the heart's relaxation phase became less turbulent, making fluid movement more efficient and coherent. Simultaneously, low-frequency CSF oscillations near the skull base increased in the 0.06 to 0.09 Hz range (P = 0.014). These low-frequency oscillations were inversely correlated with gray matter hemodynamic fluctuations — a pattern characteristic of the brain's waste-clearance state during non-REM sleep.
It's Not Just the Breathing
The most important control in this study was the breath-matched group. Fourteen participants who had no meditation experience were instructed to simply slow their breathing to match the rate of the meditators — without meditating. This group showed no significant changes in CSF flow. Neither did the repeatability control group. As co-first author David Vago stated: the effects 'were not simply due to slower breathing; they were tied specifically to the meditative state.' This distinction is critical because it isolates the cognitive component of meditation from its respiratory effects, suggesting that the mental state itself — sustained, focused attention — drives the fluid-dynamic changes.
What This Means for Long-Term Brain Health
The authors describe these CSF flow changes as 'directionally similar to sleep and opposite to aging and neurodegeneration.' This positions meditation as a potential nonpharmacological, waking model for augmenting the brain's waste-clearance system. However, important caveats remain. The study measured CSF flow dynamics, not actual waste clearance — no metabolite concentrations were tracked. All meditators were highly experienced practitioners with thousands of hours of practice; it remains unknown whether novices would show the same effects. And the study captured a snapshot during a single session, not longitudinal health outcomes. Still, this is the first evidence that focused-attention meditation can modulate cerebrospinal fluid dynamics in humans, providing a concrete physiological mechanism that may link meditation practice to long-term brain health.
References
- [1]Keating, B. A., Vago, D., Hett, K., Considine, C., Garza, M., Han, C., McKnight, C., Claassen, D. O., & Donahue, M. J. (2025). Neurofluid circulation changes during a focused attention style of mindfulness meditation. PNAS, 122(49), e2504961122.
- [2]Xie, L., et al. (2013). Sleep drives metabolite clearance from the adult brain. Science, 342(6156), 373-377.
- [3]Nedergaard, M. (2013). Neuroscience. Garbage truck of the brain. Science, 340(6140), 1529-1530.
- [4]Jessen, N. A., et al. (2015). The glymphatic system: A beginner's guide. Neurochemical Research, 40(12), 2583-2599.