How Sleep Flushes Toxins From The Brain

One of the most exciting breakthroughs in modern neural research is that cerebrospinal fluid - a clear liquid surrounding the brain and spinal cord - moves along a series of channels in the brain to flush toxins during sleep.

When cerebrospinal fluid washes in and out of the brain, it cleanses the brain of metabolic trash like a pressure washer on paving slabs. This is called the glymphatic system.

This activity occurs during sleep when channels between blood vessels in the brain widen, allowing toxins that build up during the day to flush out of the brain – a critical process for maintaining cognitive function.

Toxins!?

During the day, the brain produces toxins as a by-product of functioning. Mentally strenuous activities produce more toxins, with computer screens and other close work known to increase toxin release.

As toxin levels build, we lose the ability to concentrate and perform mental tasks, which is one of the reasons why we feel shot at the end of the day.

The main toxin in the brain is beta-amyloid, a protein associated with Alzheimer’s disease and other brain disorders.

Thankfully, sleep flushes toxins away.

The movement of cerebrospinal fluid through channels between blood cells is the main route for flushing toxins. Levels of beta-amyloid decrease during sleep, and research shows that space between neurons increases by 60% during sleep.

How it works

When we sleep, the space between blood cells in the brain widens, creating channels. Scientists have demonstrated that cerebrospinal fluid enters these channels while we sleep, flushing in and out like waves.

The process is entirely automated – a neurological function powered by deep sleep when the brain emits delta waves. This sleep period is associated with restoration and is critical to waking up feeling refreshed and rested.

Scientists do not know the precise functioning behind cerebrospinal fluid flushing in and out of the brain, but we know it happens.

What else do we know?

The process has a mechanism – the glymphatic system – defined as a macroscopic waste clearance system. Medical journals mention a system of perivascular channels formed by astroglia cells.

The cerebrospinal fluid eliminates soluble proteins and metabolites, draining away soluble waste that is dangerous to the brain.

Recent research suggests that disruptions to the glymphatic system can contribute to some brain diseases, including Alzheimer’s. The glymphatic system is suppressed in many diseases and after traumatic experiences like stroke.

Alzheimer’s is linked to beta-amyloid, a toxic protein the brain flushes during sleep. But Alzheimer’s disease symptoms must not be confused with toxic build-up, and you should speak to your GP if you are worried.

Symptoms of toxins

The brain’s ‘rinse cycle’ is critical for cognitive maintenance because it is the only way the brain can eliminate toxins. If toxins aren’t stopped, cognitive function declines rapidly, and it’s possible to die from a lack of neural restoration.

However, most of the time, we notice the effects of toxins during the day as mental fatigue, such as low concentration and struggling to find words.

We all have toxic waste in our brains from being awake, but those who perform mentally strenuous activities produce more toxins. This explains why writing a dissertation saps you of your mental ability compared to reading a book.

Deep sleep gives your brain a deep clean but not getting enough sleep hampers the process – this is one reason you feel awful after no sleep.

However, it’s critical to recognise that toxins are not the ultimate reason behind mental and cognitive decline – this can signify a more sinister health issue.

Summing up

The brain has a waste-clearance system called the glymphatic system, which washes cerebrospinal fluid in and out of the brain in waves, clearing away soluble toxins. This process is critical to maintaining brain health.

For the glymphatic system to boot up, you must enter deep sleep (NREM stage 3), the sleep stage responsible for the neurological restoration.