Sleep is often seen as a passive state, but new research shows it is an active, highly organized process in which the brain shifts gears rather than simply turning off. According to recent neuroscience findings, different brain regions remain partially awake even during deep non-REM sleep. A 2025 review in Nature Communications explained, “Dreams … also happen during deeper and calmer NREM stages … in these cases, brain activity resembles wakefulness more than deep sleep, as if the brain were ‘partially awake’.” This patchwork of awake and resting regions allows the brain to maintain alertness while performing essential maintenance.
During sleep, the brain reorganizes its activity and resources. A 2025 report in Quanta Magazine described how “the flow of blood to the brain slows down and the circulation of cerebrospinal fluid speeds up. Neurons release neurotransmitters that shift the brain’s chemistry and they start to behave differently, firing more in sync with one another.” This coordinated process helps reduce cognitive load while ramping up the brain’s cleaning functions.
Boston University researchers discovered that while sleeping, neuronal quieting is followed by a flow of blood out of the brain and a wave of cerebrospinal fluid (CSF) into it, effectively washing away metabolic waste. Laura Lewis, a BU assistant professor, said, “We have so many people who are really excited to participate because they want to get paid to sleep … But it turns out that their job is actually—secretly—almost the hardest part of our study.”
Glymphatic System: Sleep’s Rinse Cycle
Research from the University of Rochester Medical Center revealed an alternative drainage system called the glymphatic system, in which CSF moves through the brain along blood vessels, flushing out chemical waste. Maiken Nedergaard, who led the study, explained that oscillations of the neurotransmitter norepinephrine drive blood vessel contractions, which in turn propel CSF throughout the brain. Nedergaard said, “Because the brain is boxed in by the skull, the contraction and relaxation of blood vessels creates a pump that circulates the cerebrospinal fluid.”
Studies suggest this cleaning process is crucial for memory and long-term brain health, and disruptions—such as fragmented sleep or late-night caffeine—can reduce the brain’s ability to complete this nightly maintenance.
Habits That Help Your Brain Cleanse
Simple lifestyle habits can enhance the brain’s nightly reset:
During sleep, the brain reorganizes its activity and resources. A 2025 report in Quanta Magazine described how “the flow of blood to the brain slows down and the circulation of cerebrospinal fluid speeds up. Neurons release neurotransmitters that shift the brain’s chemistry and they start to behave differently, firing more in sync with one another.” This coordinated process helps reduce cognitive load while ramping up the brain’s cleaning functions.
Boston University researchers discovered that while sleeping, neuronal quieting is followed by a flow of blood out of the brain and a wave of cerebrospinal fluid (CSF) into it, effectively washing away metabolic waste. Laura Lewis, a BU assistant professor, said, “We have so many people who are really excited to participate because they want to get paid to sleep … But it turns out that their job is actually—secretly—almost the hardest part of our study.”
Glymphatic System: Sleep’s Rinse Cycle
Research from the University of Rochester Medical Center revealed an alternative drainage system called the glymphatic system, in which CSF moves through the brain along blood vessels, flushing out chemical waste. Maiken Nedergaard, who led the study, explained that oscillations of the neurotransmitter norepinephrine drive blood vessel contractions, which in turn propel CSF throughout the brain. Nedergaard said, “Because the brain is boxed in by the skull, the contraction and relaxation of blood vessels creates a pump that circulates the cerebrospinal fluid.”
Studies suggest this cleaning process is crucial for memory and long-term brain health, and disruptions—such as fragmented sleep or late-night caffeine—can reduce the brain’s ability to complete this nightly maintenance.
Habits That Help Your Brain Cleanse
Simple lifestyle habits can enhance the brain’s nightly reset:
- Maintain a consistent sleep schedule to support smooth transitions between wakefulness and sleep.
- Reduce stimulation an hour before bed to help the brain shift gears efficiently.
- Sleep in a cool, dark, and quiet room to optimize CSF circulation and energy reset.
- Engage in daytime physical activity to build sleep pressure but avoid heavy exercise just before bed.
- Take short naps strategically to refresh without interrupting deep sleep stages.
- Use gentle light and movement upon waking to signal the brain’s transition to alertness.
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